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1.
  • Ferrando, Carlos, et al. (författare)
  • Effects of oxygen on post-surgical infections during an individualised perioperative open-lung ventilatory strategy : a randomised controlled trial
  • 2020
  • Ingår i: British Journal of Anaesthesia. - : ELSEVIER SCI LTD. - 0007-0912 .- 1471-6771. ; 124:1, s. 110-120
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: We aimed to examine whether using a high fraction of inspired oxygen (FIO2) in the context of an individualised intra- and postoperative open-lung ventilation approach could decrease surgical site infection (SSI) in patients scheduled for abdominal surgery. Methods: We performed a multicentre, randomised controlled clinical trial in a network of 21 university hospitals from June 6, 2017 to July 19, 2018. Patients undergoing abdominal surgery were randomly assigned to receive a high (0.80) or conventional (0.3) FIO2 during the intraoperative period and during the first 3 postoperative hours. All patients were mechanically ventilated with an open-lung strategy, which included recruitment manoeuvres and individualised positive end-expiratory pressure for the best respiratory-system compliance, and individualised continuous postoperative airway pressure for adequate peripheral oxyhaemoglobin saturation. The primary outcome was the prevalence of SSI within the first 7 postoperative days. The secondary outcomes were composites of systemic complications, length of intensive care and hospital stay, and 6-month mortality. Results: We enrolled 740 subjects: 371 in the high FIO2 group and 369 in the low FIO2 group. Data from 717 subjects were available for final analysis. The rate of SSI during the first postoperative week did not differ between high (8.9%) and low (9.4%) FIO2 groups (relative risk [RR]: 0.94; 95% confidence interval [CI]: 0.59-1.50; P=0.90]). Secondary outcomes, such as atelectasis (7.7% vs 9.8%; RR: 0.77; 95% CI: 0.48-1.25; P=0.38) and myocardial ischaemia (0.6% [n=2] vs 0% [n=0]; P=0.47) did not differ between groups. Conclusions: An oxygenation strategy using high FIO2 compared with conventional FIO2 did not reduce postoperative SSIs in abdominal surgery. No differences in secondary outcomes or adverse events were found.
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2.
  • Ferrando, Carlos, et al. (författare)
  • Rationale and study design for an individualised perioperative open-lung ventilatory strategy with a high versus conventional inspiratory oxygen fraction (iPROVE-O2) and its effects on surgical site infection : study protocol for a randomised controlled trial
  • 2017
  • Ingår i: BMJ Open. - : BMJ. - 2044-6055. ; 7:7
  • Tidskriftsartikel (refereegranskat)abstract
    • Introduction Surgical site infection (SSI) is a serious postoperative complication that increases morbidity and healthcare costs. SSIs tend to increase as the partial pressure of tissue oxygen decreases: previous trials have focused on trying to reduce them by comparing high versus conventional inspiratory oxygen fractions (FIO 2) in the perioperative period but did not use a protocolised ventilatory strategy. The open-lung ventilatory approach restores functional lung volume and improves gas exchange, and therefore it may increase the partial pressure of tissue oxygen for a given FIO 2. The trial presented here aims to compare the efficacy of high versus conventional FIO 2 in reducing the overall incidence of SSIs in patients by implementing a protocolised and individualised global approach to perioperative open-lung ventilation. Methods and analysis This is a comparative, prospective, multicentre, randomised and controlled two-arm trial that will include 756 patients scheduled for abdominal surgery. The patients will be randomised into two groups: (1) a high FIO 2 group (80% oxygen; FIO 2 of 0.80) and (2) a conventional FIO 2 group (30% oxygen; FIO 2 of 0.30). Each group will be assessed intra-and postoperatively. The primary outcome is the appearance of postoperative SSI complications. Secondary outcomes are the appearance of systemic and pulmonary complications. Ethics and dissemination The iPROVE-O2 trial has been approved by the Ethics Review Board at the reference centre (the Hospital Clinico Universitario in Valencia). Informed consent will be obtained from all patients before their participation. If the approach using high FIO 2 during individualised open-lung ventilation decreases SSIs, use of this method will become standard practice for patients scheduled for future abdominal surgery. Publication of the results is anticipated in early 2019.
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3.
  • Acosta, Cecilia M., et al. (författare)
  • Doppler images of intra-pulmonary shunt within atelectasis in anesthetized children
  • 2016
  • Ingår i: Critical Ultrasound Journal. - : Springer Science and Business Media LLC. - 2036-3176 .- 2036-7902. ; 8
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Doppler images of pulmonary vessels in pulmonary diseases associated with subpleural consolidations have been described. Color Doppler easily identifies such vessels within consolidations while spectral Doppler analysis allows the differentiation between pulmonary and bronchial arteries. Thus, Doppler helps in diagnosing the nature of consolidations. To our knowledge, Doppler analysis of pulmonary vessels within anesthesia-induced atelectasis has never been described before. The aim of this case series is to demonstrate the ability of lung ultrasound to detect the shunting of blood within atelectatic lung areas in anesthetized children.Findings: Three anesthetized and mechanically ventilated children were scanned in the supine position using a high-resolution linear probe of 6-12 MHz. Once subpleural consolidations were detected in the most dependent posterior lung regions, the probe was rotated such that its long axis followed the intercostal space. In this oblique position, color Doppler mapping was performed to detect blood flow within the consolidation. Thereafter, pulsed waved spectral Doppler was applied in the previously identified vessels during a short expiratory pause, which prevented interferences from respiratory motion. Different flow patterns were identified which corresponded to both, pulmonary and bronchial vessels. Finally, a lung recruitment maneuver was performed which leads to the complete resolution of the aforementioned consolidation thereby confirming the pathophysiological entity of anesthesia-induced atelectasis.Conclusions: Lung ultrasound is a non-invasive imaging tool that not only enables the diagnosis of anesthesia-induced atelectasis in pediatric patients but also analysis of shunting blood within this consolidation.
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4.
  • Acosta, Cecilia M., et al. (författare)
  • Effect of an Individualized Lung Protective Ventilation on Lung Strain and Stress in Children Undergoing Laparoscopy : An Observational Cohort Study
  • 2024
  • Ingår i: Anesthesiology. - : American Society of Anesthesiologists. - 0003-3022 .- 1528-1175. ; 140:3, s. 430-441
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Exaggerated lung strain and stress could damage lungs in anesthetized children. The authors hypothesized that the association of capnoperitoneum and lung collapse in anesthetized children increases lung strain-stress. Their primary aim was to describe the impact of capnoperitoneum on lung strain-stress and the effects of an individualized protective ventilation during laparoscopic surgery in children.Methods: The authors performed an observational cohort study in healthy children aged 3 to 7 yr scheduled for laparoscopic surgery in a community hospital. All received standard protective ventilation with 5 cm H2O of positive end-expiratory pressure (PEEP). Children were evaluated before capnoperitoneum, during capnoperitoneum before and after lung recruitment and optimized PEEP (PEEP adjusted to get end-expiratory transpulmonary pressure of 0), and after capnoperitoneum with optimized PEEP. The presence of lung collapse was evaluated by lung ultrasound, positive Air-Test (oxygen saturation measured by pulse oximetry 96% or less breathing 21% O2 for 5 min), and negative end-expiratory transpulmonary pressure. Lung strain was calculated as tidal volume/end-expiratory lung volume measured by capnodynamics, and lung stress as the end-inspiratory transpulmonary pressure.Results: The authors studied 20 children. Before capnoperitoneum, mean lung strain was 0.20 ± 0.07 (95% CI, 0.17 to 0.23), and stress was 5.68 ± 2.83 (95% CI, 4.44 to 6.92) cm H2O. During capnoperitoneum, 18 patients presented lung collapse and strain (0.29 ± 0.13; 95% CI, 0.23 to 0.35; P < 0.001) and stress (5.92 ± 3.18; 95% CI, 4.53 to 7.31 cm H2O; P = 0.374) increased compared to before capnoperitoneum. During capnoperitoneum and optimized PEEP, children presenting lung collapse were recruited and optimized PEEP was 8.3 ± 2.2 (95% CI, 7.3 to 9.3) cm H2O. Strain returned to values before capnoperitoneum (0.20 ± 0.07; 95% CI, 0.17 to 0.22; P = 0.318), but lung stress increased (7.29 ± 2.67; 95% CI, 6.12 to 8.46 cm H2O; P = 0.020). After capnoperitoneum, strain decreased (0.18 ± 0.04; 95% CI, 0.16 to 0.20; P = 0.090), but stress remained higher (7.25 ± 3.01; 95% CI, 5.92 to 8.57 cm H2O; P = 0.024) compared to before capnoperitoneum.Conclusions: Capnoperitoneum increased lung strain in healthy children undergoing laparoscopy. Lung recruitment and optimized PEEP during capnoperitoneum decreased lung strain but slightly increased lung stress. This little rise in pulmonary stress was maintained within safe, lung-protective, and clinically acceptable limits.
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5.
  • Acosta, Cecilia M., et al. (författare)
  • Prevention of atelectasis by continuous positive airway pressure in anaesthetised children : A randomised controlled study
  • 2021
  • Ingår i: European Journal of Anaesthesiology. - : Wolters Kluwer. - 0265-0215 .- 1365-2346. ; 38:1, s. 41-48
  • Tidskriftsartikel (refereegranskat)abstract
    • BACKGROUND Continuous positive airway pressure (CPAP) prevents peri-operative atelectasis in adults, but its effect in children has not been quantified.OBJECTIVE The aim of this study was to evaluate the role of CPAP in preventing postinduction and postoperative atelectasis in children under general anaesthesia.DESIGN A randomised controlled study.SETTING Single-institution study, community hospital, Mar del Plata. Argentina.PATIENTS We studied 42 children, aged 6 months to 7 years, American Society of Anesthesiologists physical status class I, under standardised general anaesthesia.INTERVENTIONS Patients were randomised into two groups: Control group (n = 21): induction and emergence of anaesthesia without CPAP; and CPAP group (n = 21): 5 cmH2O of CPAP during induction and emergence of anaesthesia. Lung ultrasound (LUS) imaging was performed before and 5 min after anaesthesia induction. Children without atelectasis were ventilated in the same manner as the Control group with standard ventilatory settings including 5 cmH2O of PEEP. Children with atelectasis received a recruitment manoeuvre followed by standard ventilation with 8 cmH2O of PEEP. Then, at the end of surgery, LUS images were repeated before tracheal extubation and 60 min after awakening.MAIN OUTCOME MEASURES Lung aeration score and atelectasis assessed by LUS.RESULTS Before anaesthesia, all children were free of atelectasis. After induction, 95% in the Control group developed atelectasis compared with 52% of patients in the CPAP group (P < 0.0001). LUS aeration scores were higher (impaired aeration) in the Control group than the CPAP group (8.8 ± 3.8 vs. 3.5 ± 3.3 points; P < 0.0001). At the end of surgery, before tracheal extubation, atelectasis was observed in 100% of children in the Control and 29% of the CPAP group (P < 0.0001) with a corresponding aeration score of 9.6 ± 3.2 and 1.8 ± 2.3, respectively (P < 0.0001). After surgery, 30% of children in the Control group and 10% in the CPAP group presented with residual atelectasis (P < 0.0001) also corresponding to a higher aeration score in the Control group (2.5 ± 3.1) when compared with the CPAP group (0.5 ± 1.5; P < 0.01).CONCLUSION The use of 5 cmH2O of CPAP in healthy children of the studied age span during induction and emergence of anaesthesia effectively prevents atelectasis, with benefits maintained during the first postoperative hour.TRIAL REGISTRY Clinicaltrials.gov NCT03461770.
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6.
  • Borges, João Batista, et al. (författare)
  • Regional Lung Perfusion estimated by Electrical Impedance Tomography in a piglet model of lung collapse
  • 2011
  • Ingår i: Journal of applied physiology. - : American Physiological Society. - 8750-7587 .- 1522-1601. ; 112:1, s. 225-236
  • Tidskriftsartikel (refereegranskat)abstract
    • The assessment of the regional match between alveolar ventilation and perfusion in critically ill patients requires simultaneous measurements of both parameters. Ideally, assessment of lung perfusion should be performed in real-time with an imaging technology which provides, through fast acquisition of sequential images, information about the regional dynamics or regional kinetics of an appropriate tracer. We present a novel electrical impedance tomography (EIT) based method that quantitatively estimates regional lung perfusion based on first-pass kinetics of a bolus of hypertonic saline contrast. Pulmonary blood flow was measured in six piglets during control and unilateral or bilateral lung collapse conditions. The first-pass kinetics method showed good agreement with the estimates obtained by single-photon-emission computerized tomography (SPECT). The mean difference (SPECT minus EIT) between fractional blood flow to lung areas suffering atelectasis was -0.6 %, with a standard deviation of 2.9 %. This method outperformed the estimates of lung perfusion based on impedance-pulsatility. In conclusion, we describe a novel method based on Electrical Impedance Tomography for estimating regional lung perfusion at the bedside. In both, healthy and injured lung conditions, the distribution of pulmonary blood flow as assessed by EIT agreed well with the one obtained by SPECT. The method proposed in this paper has the potential to contribute to a better understanding of the behavior of regional perfusion under different lung and therapeutic conditions.
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7.
  • Carraminana, Albert, et al. (författare)
  • Rationale and Study Design for an Individualized Perioperative Open Lung Ventilatory Strategy in Patients on One-Lung Ventilation (iPROVE-OLV)
  • 2019
  • Ingår i: Journal of Cardiothoracic and Vascular Anesthesia. - : W B SAUNDERS CO-ELSEVIER INC. - 1053-0770 .- 1532-8422. ; 33:9, s. 2492-2502
  • Tidskriftsartikel (refereegranskat)abstract
    • Objective: The aim of this clinical trial is to examine whether it is possible to reduce postoperative complications using an individualized perioperative ventilatory strategy versus using a standard lung-protective ventilation strategy in patients scheduled for thoracic surgery requiring one-lung ventilation. Design: International, multicenter, prospective, randomized controlled clinical trial. Setting: A network of university hospitals. Participants: The study comprises 1,380 patients scheduled for thoracic surgery. Interventions: The individualized group will receive intraoperative recruitment maneuvers followed by individualized positive end-expiratory pressure (open lung approach) during the intraoperative period plus postoperative ventilatory support with high-flow nasal cannula, whereas the control group will be managed with conventional lung-protective ventilation. Measurements and Main Results: Individual and total number of postoperative complications, including atelectasis, pneumothorax, pleural effusion, pneumonia, acute lung injury; unplanned readmission and reintubation; length of stay and death in the critical care unit and in the hospital will be analyzed for both groups. The authors hypothesize that the intraoperative application of an open lung approach followed by an individual indication of high-flow nasal cannula in the postoperative period will reduce pulmonary complications and length of hospital stay in high-risk surgical patients. (C) 2019 Published by Elsevier Inc.
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8.
  • Ferrando, Carlos, et al. (författare)
  • A noninvasive postoperative clinical score to identify patients at risk for postoperative pulmonary complications : the Air-Test Score
  • 2020
  • Ingår i: Minerva Anestesiologica. - : EDIZIONI MINERVA MEDICA. - 0375-9393 .- 1827-1596. ; 86:4, s. 404-415
  • Tidskriftsartikel (refereegranskat)abstract
    • BACKGROUND: Postoperative pulmonary complications (PPCs) negatively affect morbidity, healthcare costs and postsurgical survival. Preoperative and intraoperative peripheral oxyhemoglobin saturation (SpO(2)) levels are independent risk factors for postoperative pulmonary complications (PPCs). The air-test assesses the value of SpO(2) while breathing room-air. We aimed at building a clinical score that includes the air-test for predicting the risk for PPCs. METHODS: This is a development and validation study in patients -randomly divided into two cohorts- from a large randomized clinical trial (iPROVE) that enrolled 964 intermediate-to-high risk patients scheduled for abdominal surgery. Arterial oxygenation was assessed on room-air in the preoperative period (preoperative air-test) and 3h after admission to the postoperative care unit (postoperative air-test). The air-test was defined as positive or negative if SpO(2) was <= 96% or >96%, respectively. Positive air-tests were stratified into weak (93-96%) or strong (<93%). The primary outcome was a composite of moderate-to-severe PPCs during the first seven postoperative days. RESULTS: A total of 902 patients were included in the final analysis (542 in the development cohort and 360 in the validation cohort). Regression analysis identified five independent risk factors for PPC: age. type of surgery, pre- and postoperative air-test, and atelectasis. The area under the receiver operating characteristic curve (AUC) was 0.79 (95% CI: 0.75-0.82) when including these five independent predictors. We built a simplified score termed "air-test score" by using only the pre- and postoperative SpO(2) , resulting in an AUC of 0.72 (95% CI: 0.67-0.76) for the derivation and 0.72 (95% CI: 0.66-0.78) for the validation cohort, respectively. The air-test score stratified patients into four levels of risk, with PPCs ranging from <15% to >75%. CONCLUSIONS: The simple, non-invasive and inexpensive bedside air-test score, evaluating pre- and postoperatively SpO(2) measured on room-air, helps to predict the risk for PPCs.
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9.
  • Ferrando, Carlos, et al. (författare)
  • Adjusting tidal volume to stress index in an open lung condition optimizes ventilation and prevents overdistension in an experimental model of lung injury and reduced chest wall compliance
  • 2015
  • Ingår i: Critical Care. - : Springer Science and Business Media LLC. - 1364-8535 .- 1466-609X. ; 19
  • Tidskriftsartikel (refereegranskat)abstract
    • Introduction: The stress index ( SI), a parameter derived from the shape of the pressure-time curve, can identify injurious mechanical ventilation. We tested the hypothesis that adjusting tidal volume (VT) to a non-injurious SI in an open lung condition avoids hypoventilation while preventing overdistension in an experimental model of combined lung injury and low chest-wall compliance (Ccw). Methods: Lung injury was induced by repeated lung lavages using warm saline solution, and Ccw was reduced by controlled intra-abdominal air-insufflation in 22 anesthetized, paralyzed and mechanically ventilated pigs. After injury animals were recruited and submitted to a positive end-expiratory pressure (PEEP) titration trial to find the PEEP level resulting in maximum compliance. During a subsequent four hours of mechanical ventilation, VT was adjusted to keep a plateau pressure (Pplat) of 30 cmH2O (Pplat-group, n = 11) or to a SI between 0.95 and 1.05 (SI-group, n = 11). Respiratory rate was adjusted to maintain a 'normal' PaCO2 (35 to 65 mmHg). SI, lung mechanics, arterial-blood gases haemodynamics pro-inflammatory cytokines and histopathology were analyzed. In addition Computed Tomography (CT) data were acquired at end expiration and end inspiration in six animals. Results: PaCO2 was significantly higher in the Pplat-group (82 versus 53 mmHg, P = 0.01), with a resulting lower pH (7.19 versus 7.34, P = 0.01). We observed significant differences in VT (7.3 versus 5.4 mlKg-1, P = 0.002) and Pplat values (30 versus 35 cmH2O, P = 0.001) between the Pplat-group and SI-group respectively. SI (1.03 versus 0.99, P = 0.42) and end-inspiratory transpulmonary pressure (PTP) (17 versus 18 cmH2O, P = 0.42) were similar in the Pplat-and SI-groups respectively, without differences in overinflated lung areas at end-inspiration in both groups. Cytokines and histopathology showed no differences. Conclusions: Setting tidal volume to a non-injurious stress index in an open lung condition improves alveolar ventilation and prevents overdistension without increasing lung injury. This is in comparison with limited Pplat protective ventilation in a model of lung injury with low chest-wall compliance.
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10.
  • Ferrando, Carlos, et al. (författare)
  • Individualised perioperative open-lung approach versus standard protective ventilation in abdominal surgery (iPROVE) : a randomised controlled trial
  • 2018
  • Ingår i: The Lancet Respiratory Medicine. - : ELSEVIER SCI LTD. - 2213-2600 .- 2213-2619. ; 6:3, s. 193-203
  • Tidskriftsartikel (refereegranskat)abstract
    • Background The effects of individualised perioperative lung-protective ventilation (based on the open-lung approach [OLA]) on postoperative complications is unknown. We aimed to investigate the effects of intraoperative and postoperative ventilatory management in patients scheduled for abdominal surgery, compared with standard protective ventilation. Methods We did this prospective, multicentre, randomised controlled trial in 21 teaching hospitals in Spain. We enrolled patients who were aged 18 years or older, were scheduled to have abdominal surgery with an expected time of longer than 2 h, had intermediate-to-high-risk of developing postoperative pulmonary complications, and who had a body-mass index less than 35 kg/m(2). Patients were randomly assigned (1: 1: 1: 1) online to receive one of four lung-protective ventilation strategies using low tidal volume plus positive end-expiratory pressure (PEEP): open-lung approach (OLA)-iCPAP (individualised intraoperative ventilation [individualised PEEP after a lung recruitment manoeuvre] plus individualised postoperative continuous positive airway pressure [CPAP]), OLA-CPAP (intraoperative individualised ventilation plus postoperative CPAP), STD-CPAP (standard intraoperative ventilation plus postoperative CPAP), or STD-O-2 (standard intraoperative ventilation plus standard postoperative oxygen therapy). Patients were masked to treatment allocation. Investigators were not masked in the operating and postoperative rooms; after 24 h, data were given to a second investigator who was masked to allocations. The primary outcome was a composite of pulmonary and systemic complications during the first 7 postoperative days. We did the primary analysis using the modified intention-to-treat population. This trial is registered with ClinicalTrials.gov, number NCT02158923. Findings Between Jan 2, 2015, and May 18, 2016, we enrolled 1012 eligible patients. Data were available for 967 patients, whom we included in the final analysis. Risk of pulmonary and systemic complications did not differ for patients in OLA-iCPAP (110 [46%] of 241, relative risk 0.89 [95% CI 0.74-1.07; p=0.25]), OLA-CPAP (111 [47%] of 238, 0.91 [0.76-1.09; p=0.35]), or STD-CPAP groups (118 [48%] of 244, 0.95 [0.80-1.14; p=0.65]) when compared with patients in the STD-O-2 group (125 [51%] of 244). Intraoperatively, PEEP was increased in 69 (14%) of patients in the standard perioperative ventilation groups because of hypoxaemia, and no patients from either of the OLA groups required rescue manoeuvres. Interpretation In patients who have major abdominal surgery, the different perioperative open lung approaches tested in this study did not reduce the risk of postoperative complications when compared with standard lung-protective mechanical ventilation.
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11.
  • Ferrando, Carlos, et al. (författare)
  • Individualised, perioperative open-lung ventilation strategy during one-lung ventilation (iPROVE-OLV) : a multicentre, randomised, controlled clinical trial
  • 2024
  • Ingår i: The Lancet Respiratory Medicine. - : Elsevier. - 2213-2600 .- 2213-2619. ; 12:3, s. 195-206
  • Tidskriftsartikel (refereegranskat)abstract
    • Background It is uncertain whether individualisation of the perioperative open-lung approach (OLA) to ventilation reduces postoperative pulmonary complications in patients undergoing lung resection. We compared a perioperative individualised OLA (iOLA) ventilation strategy with standard lung-protective ventilation in patients undergoing thoracic surgery with one-lung ventilation. Methods This multicentre, randomised controlled trial enrolled patients scheduled for open or video-assisted thoracic surgery using one-lung ventilation in 25 participating hospitals in Spain, Italy, Turkey, Egypt, and Ecuador. Eligible adult patients (age >= 18 years) were randomly assigned to receive iOLA or standard lung-protective ventilation. Eligible patients (stratified by centre) were randomly assigned online by local principal investigators, with an allocation ratio of 1:1. Treatment with iOLA included an alveolar recruitment manoeuvre to 40 cm H2O of end-inspiratory pressure followed by individualised positive end-expiratory pressure (PEEP) titrated to best respiratory system compliance, and individualised postoperative respiratory support with high-flow oxygen therapy. Participants allocated to standard lungprotective ventilation received combined intraoperative 4 cm H2O of PEEP and postoperative conventional oxygen therapy. The primary outcome was a composite of severe postoperative pulmonary complications within the first 7 postoperative days, including atelectasis requiring bronchoscopy, severe respiratory failure, contralateral pneumothorax, early extubation failure (rescue with continuous positive airway pressure, non-invasive ventilation, invasive mechanical ventilation, or reintubation), acute respiratory distress syndrome, pulmonary infection, bronchopleural fistula, and pleural empyema. Due to trial setting, data obtained in the operating and postoperative rooms for routine monitoring were not blinded. At 24 h, data were acquired by an investigator blinded to group allocation. All analyses were performed on an intention-to-treat basis. This trial is registered with ClinicalTrials.gov, NCT03182062, and is complete. Findings Between Sept 11, 2018, and June 14, 2022, we enrolled 1380 patients, of whom 1308 eligible patients (670 [434 male, 233 female, and three with missing data] assigned to iOLA and 638 [395 male, 237 female, and six with missing data] to standard lung-protective ventilation) were included in the final analysis. The proportion of patients with the composite outcome of severe postoperative pulmonary complications within the first 7 postoperative days was lower in the iOLA group compared with the standard lung-protective ventilation group (40 [6%] vs 97 [15%], relative risk 0 center dot 39 [95% CI 0 center dot 28 to 0 center dot 56]), with an absolute risk difference of -9 center dot 23 (95% CI -12 center dot 55 to -5 center dot 92). Recruitment manoeuvre-related adverse events were reported in five patients. Interpretation Among patients subjected to lung resection under one-lung ventilation, iOLA was associated with a reduced risk of severe postoperative pulmonary complications when compared with conventional lung-protective ventilation. Funding Instituto de Salud Carlos III and the European Regional Development Funds. Copyright (c) 2023 Elsevier Ltd. All rights reserved.
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12.
  • Ferrando, Carlos, et al. (författare)
  • Intraoperative open lung condition and postoperative pulmonary complications. A secondary analysis of iPROVE and iPROVE-O2 trials
  • 2022
  • Ingår i: Acta Anaesthesiologica Scandinavica. - : John Wiley & Sons. - 0001-5172 .- 1399-6576. ; 66:1, s. 30-39
  • Tidskriftsartikel (refereegranskat)abstract
    • Background The preventive role of an intraoperative recruitment maneuver plus open lung approach (RM + OLA) ventilation on postoperative pulmonary complications (PPC) remains unclear. We aimed at investigating whether an intraoperative open lung condition reduces the risk of developing a composite of PPCs.Methods Post hoc analysis of two randomized controlled trials including patients undergoing abdominal surgery. Patients were classified according to the intraoperative lung condition as "open" (OL) or "non-open" (NOL) if PaO2/FIO2 ratio was >= or <400 mmHg, respectively. We used a multivariable logistic regression model that included potential confounders selected with directed acyclic graphs (DAG) using Dagitty software built with variables that were considered clinically relevant based on biological mechanism or evidence from previously published data. PPCs included severe acute respiratory failure, acute respiratory distress syndrome, and pneumonia.Results A total of 1480 patients were included in the final analysis, with 718 (49%) classified as OL. The rate of severe PPCs during the first seven postoperative days was 6.0% (7.9% in the NOL and 4.4% in the OL group, p = .007). OL was independently associated with a lower risk for severe PPCs during the first 7 and 30 postoperative days [odds ratio of 0.58 (95% CI 0.34-0.99, p = .04) and 0.56 (95% CI 0.34-0.94, p = .03), respectively].Conclusions An intraoperative open lung condition was associated with a reduced risk of developing severe PPCs in intermediate-to-high risk patients undergoing abdominal surgery. Trial registration: Registered at clinicaltrials.gov NCT02158923 (iPROVE), NCT02776046 (iPROVE-O2).
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13.
  • Ferrando, Carlos, et al. (författare)
  • Open lung approach versus standard protective strategies : Effects on driving pressure and ventilatory efficiency during anesthesia - A pilot, randomized controlled trial
  • 2017
  • Ingår i: PLOS ONE. - : PUBLIC LIBRARY SCIENCE. - 1932-6203. ; 12:5
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Low tidal volume (VT) during anesthesia minimizes lung injury but may be associated to a decrease in functional lung volume impairing lung mechanics and efficiency. Lung recruitment (RM) can restore lung volume but this may critically depend on the post-RM selected PEEP. This study was a randomized, two parallel arm, open study whose primary outcome was to compare the effects on driving pressure of adding a RM to low-VT ventilation, with or without an individualized post-RM PEEP in patients without known previous lung disease during anesthesia.Methods: Consecutive patients scheduled for major abdominal surgery were submitted to low-VT ventilation (6 ml.kg(-1)) and standard PEEP of 5 cmH(2)O (pre-RM, n = 36). After 30 min estabilization all patients received a RM and were randomly allocated to either continue with the same PEEP (RM-5 group, n = 18) or to an individualized open-lung PEEP (OL-PEEP) (Open Lung Approach, OLA group, n = 18) defined as the level resulting in maximal Cdyn during a decremental PEEP trial. We compared the effects on driving pressure and lung efficiency measured by volumetric capnography.Results: OL-PEEP was found at 8 +/- 2 cmH(2)O. 36 patients were included in the final analysis. When compared with pre-RM, OLA resulted in a 22% increase in compliance and a 28% decrease in driving pressure when compared to pre-RM. These parameters did not improve in the RM-5. The trend of the DP was significantly different between the OLA and RM-5 groups (p = 0.002). VDalv/VTalv was significantly lower in the OLA group after the RM (p = 0.035).Conclusions: Lung recruitment applied during low-VT ventilation improves driving pressure and lung efficiency only when applied as an open-lung strategy with an individualized PEEP in patients without lung diseases undergoing major abdominal surgery.
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14.
  • Ferrando, Carlos, et al. (författare)
  • Rationale and study design for an individualized perioperative open lung ventilatory strategy (iPROVE) : study protocol for a randomized controlled trial
  • 2015
  • Ingår i: Trials. - : Springer Science and Business Media LLC. - 1745-6215. ; 16
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Postoperative pulmonary and non-pulmonary complications are common problems that increase morbidity and mortality in surgical patients, even though the incidence has decreased with the increased use of protective lung ventilation strategies. Previous trials have focused on standard strategies in the intraoperative or postoperative period, but without personalizing these strategies to suit the needs of each individual patient and without considering both these periods as a global perioperative lung-protective approach. The trial presented here aims at comparing postoperative complications when using an individualized ventilatory management strategy in the intraoperative and immediate postoperative periods with those when using a standard protective ventilation strategy in patients scheduled for major abdominal surgery. Methods: This is a comparative, prospective, multicenter, randomized, and controlled, four-arm trial that will include 1012 patients with an intermediate or high risk for postoperative pulmonary complications. The patients will be divided into four groups: (1) individualized perioperative group: intra-and postoperative individualized strategy; (2) intraoperative individualized strategy + postoperative continuous positive airway pressure (CPAP); (3) intraoperative standard ventilation + postoperative CPAP; (4) intra-and postoperative standard strategy (conventional strategy). The primary outcome is a composite analysis of postoperative complications. Discussion: The Individualized Perioperative Open-lung Ventilatory Strategy (iPROVE) is the first multicenter, randomized, and controlled trial to investigate whether an individualized perioperative approach prevents postoperative pulmonary complications.
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15.
  • Ferrando, Carlos, et al. (författare)
  • The accuracy of postoperative, non-invasive Air-Test to diagnose atelectasis in healthy patients after surgery : a prospective, diagnostic pilot study
  • 2017
  • Ingår i: BMJ Open. - : BMJ. - 2044-6055. ; 7:5
  • Tidskriftsartikel (refereegranskat)abstract
    • Objective To assess the diagnostic accuracy of peripheral capillary oxygen saturation (SpO(2)) while breathing room air for 5 min (the 'Air-Test') in detecting postoperative atelectasis. Design Prospective cohort study. Diagnostic accuracy was assessed by measuring the agreement between the index test and the reference standard CT scan images. Setting Postanaesthetic care unit in a tertiary hospital in Spain. Participants Three hundred and fifty patients from 12 January to 7 February 2015; 170 patients scheduled for surgery under general anaesthesia who were admitted into the postsurgical unit were included. Intervention The Air-Test was performed in conscious extubated patients after a 30 min stabilisation period during which they received supplemental oxygen therapy via a venturi mask. The Air-Test was defined as positive when SpO(2) was >= 96% and negative when SpO(2) was >= 97%. Arterial blood gases were measured in all patients at the end of the Air-Test. In the subsequent 25 min, the presence of atelectasis was evaluated by performing a CT scan in 59 randomly selected patients. Main outcome measures The primary study outcome was assessment of the accuracy of the Air-Test for detecting postoperative atelectasis compared with the reference standard. The secondary outcome was the incidence of positive Air-Test results. Results The Air-Test diagnosed postoperative atelectasis with an area under the receiver operating characteristic curve of 0.90 (95% CI 0.82 to 0.98) with a sensitivity of 82.6% and a specificity of 87.8%. The presence of atelectasis was confirmed by CT scans in all patients (30/30) with positive and in 5 patients (17%) with negative Air-Test results. Based on the Air-Test, postoperative atelectasis was present in 36% of the patients (62 out of 170). Conclusion The Air-Test may represent an accurate, simple, inexpensive and non-invasive method for diagnosing postoperative atelectasis.
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16.
  • Garcia-Fernandez, Javier, et al. (författare)
  • Programming pressure support ventilation in pediatric patients in ambulatory surgery with a laryngeal mask airway.
  • 2007
  • Ingår i: Anesthesia and Analgesia. - : Ovid Technologies (Wolters Kluwer Health). - 0003-2999 .- 1526-7598. ; 105:6, s. 1585-1591
  • Tidskriftsartikel (refereegranskat)abstract
    • BACKGROUND: Anesthesia workstations with pressure support ventilation (PSV) are available, but there are few studies published on how to program flow-triggered PSV using a laryngeal mask airway (LMA) under general anesthesia in pediatric patients. METHODS: We studied 60 ASA I and II patients, from 2 mo to 14 yr, scheduled for ambulatory surgery under combined general and regional anesthesia with a LMA. Patients were classified according to their body weight as follows: Group A ≤10 kg, Group B 11–20 kg, and Group C >20 kg. All were ventilated in PSV using the following settings: positive end-expiratory pressure of 4 cm H2O, the minimum flow-trigger without provoking auto-triggering, and the minimum level of pressure support to obtain 10 mL/kg of tidal volume. RESULTS: The flow-trigger most frequently used in our study was 0.4 L/min, ranging from 0.2 to 0.6 L/min. We found no correlation between the flow-trigger setting and the patient’s age, weight, compliance, resistance, or respiratory rate. There was a good correlation between the level of pressure support (Group A = 15 cm H2O, Group B = 10 cm H2O and Group C = 9 cm H2O) and age (P < 0.001), weight (P < 0.001), dynamic compliance (P < 0.001), and airway resistances (P < 0.001). CONCLUSIONS: PSV with a Proseal™ LMA in outpatient pediatric anesthesia can be programmed simply using the common clinical noninvasive variables studied. However, more studies are needed to estimate the level of pressure support that may be required in other clinical situations (respiratory pathology, endotracheal tubes, or other types of surgeries) or with other anesthesia workstations. IMPLICATIONS: This study evaluates the ability to administer positive pressure support ventilation through a laryngeal mask airway to anesthetized, spontaneously breathing children.
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17.
  • Gogniat, Emiliano, et al. (författare)
  • Dead space analysis at different levels of positive end-expiratory pressure in acute respiratory distress syndrome patients
  • 2018
  • Ingår i: Journal of critical care. - : W B SAUNDERS CO-ELSEVIER INC. - 0883-9441 .- 1557-8615. ; 45, s. 231-238
  • Tidskriftsartikel (refereegranskat)abstract
    • Purpose: To analyze the effects of positive end-expiratory pressure (PEEP) on Bohr's dead space (VDBohr/VT) in patients with acute respiratory distress syndrome (ARDS).Material and methods: Fourteen ARDS patients under lung protective ventilation settingswere submitted to 4 different levels of PEEP (0, 6, 10, 16 cmH(2)O). Respiratory mechanics, hemodynamics and volumetric capnography were recorded at each protocol step.Results: Two groups of patients responded differently to PEEP when comparing baseline with 16-PEEP: those in which driving pressure increased > 15% (Delta P.(15%), n = 7, p = .016) and those in which the change was <= 15% (Delta P-<= 15%, n = 7, p = .700). VDBohr/VT was higher in Delta P-<= 15% than in Delta P-<= 15% patients at baseline ventilation [0.58 (0.49-0.60) vs 0.46 (0.43-0.46) p = .018], at 0-PEEP [0.50 (0.47-0.54) vs 0.41 (0.40-0.43) p = .012], at 6-PEEP [0.55 (0.49-0.57) vs 0.44 (0.42-0.45) p = .008], at 10-PEEP [0.59 (0.51-0.59) vs 0.45 (0.44-0.46) p = .006] and at 16-PEEP [0.61 (0.56-0.65) vs 0.47 (0.45-0.48) p =. 001]. We found a good correlation between Delta P and VDBohr/VT only in the Delta P.(15%) group (r = 0.74, p < .001).Conclusions: Increases in PEEP result in higher VDBohr/VT only when associated with an increase in driving pressure.
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18.
  • Longo, Silvina, et al. (författare)
  • Lung recruitment improves right ventricular performance after cardiopulmonary bypass A randomised controlled trial
  • 2017
  • Ingår i: European Journal of Anaesthesiology. - 0265-0215 .- 1365-2346. ; 34:2, s. 66-74
  • Tidskriftsartikel (refereegranskat)abstract
    • BACKGROUND Atelectasis after cardiopulmonary bypass (CPB) can affect right ventricular (RV) performance by increasing its outflow impedance. OBJECTIVE The aim of this study was to determine whether a lung recruitment manoeuvre improves RV function by re-aerating the lung after CPB. DESIGN Randomised controlled study. SETTING Single-institution study, community hospital, Cordoba, Argentina. PATIENTS Forty anaesthetised patients with New York Heart Association class I or II, preoperative left ventricular ejection fraction at least 50% and Euroscore 6 or less scheduled for cardiac surgery with CPB. INTERVENTIONS Patients were assigned to receive either standard ventilation with 6 cmH(2)O of positive end-expiratory pressure (PEEP; group C, n = 20) or standard ventilation with a recruitment manoeuvre and 10 cmH(2)O of PEEP after surgery (group RM, n = 20). RV function, left ventricular cardiac index (CI) and lung aeration were assessed by transoesophageal echocardiography (TOE) before, at the end of surgery and 30 min after surgery. MAIN OUTCOME MEASURES RV function parameters and atelectasis assessed by TOE. RESULTS Haemodynamic data and atelectasis were similar between groups before surgery. At the end of surgery, CI had decreased from 2.9 +/- 1.1 to 2.6 +/- 0.9 l min(-1) m(-2) in group C (P = 0.24) and from 2.8 +/- 1.0 to 2.6 +/- 0.8 l min(-1) m +/- 2 in group RM (P = 0.32). TOE-derived RV function parameters confirmed a mild decrease in RV performance in 95% of patients, without significant differences between groups (multivariate Hotelling t-test P = 0.16). Atelectasis was present in 18 patients in group C and 19 patients in group RM (P = 0.88). After surgery, CI decreased further from 2.6 to 2.4 l min(-)1 m(-2) in group C (P = 0.17) but increased from 2.6 to 3.7 l min(-1) m(-2) in group RM (P<0.001). TOE-derived RV function parameters improved only in group RM (Hotelling t-test P<0.001). Atelectasis was present in 100% of patients in group C but only in 10% of those in group RM (P<0.001). CONCLUSION Atelectasis after CPB impairs RV function but this can be resolved by lung recruitment using 10 cm H2O of PEEP.
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19.
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20.
  • Roldan, Rollin, et al. (författare)
  • Sequential lateral positioning as a new lung recruitment maneuver : an exploratory study in early mechanically ventilated Covid-19 ARDS patients
  • 2022
  • Ingår i: Annals of Intensive Care. - : Springer Nature. - 2110-5820. ; 12:1
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: A sequential change in body position from supine-to-both lateral positions under constant ventilatory settings could be used as a postural recruitment maneuver in case of acute respiratory distress syndrome (ARDS), provided that sufficient positive end-expiratory pressure (PEEP) prevents derecruitment. This study aims to evaluate the feasibility and physiological effects of a sequential postural recruitment maneuver in early mechanically ventilated COVID-19 ARDS patients. Methods: A cohort of 15 patients receiving lung-protective mechanical ventilation in volume-controlled with PEEP based on recruitability were prospectively enrolled and evaluated in five sequentially applied positions for 30 min each: Supine-baseline; Lateral-1st side; 2nd Supine; Lateral-2nd side; Supine-final. PEEP level was selected using the recruitment-to-inflation ratio (R/I ratio) based on which patients received PEEP 12 cmH(2)O for R/I ratio <= 0.5 or PEEP 15 cmH(2)O for R/I ratio > 0.5. At the end of each period, we measured respiratory mechanics, arterial blood gases, lung ultrasound aeration, end-expiratory lung impedance (EELI), and regional distribution of ventilation and perfusion using electric impedance tomography (EIT). Results: Comparing supine baseline and final, respiratory compliance (29 +/- 9 vs 32 +/- 8 mL/cmH(2)O; p < 0.01) and PaO2/FlO(2) ratio (138 +/- 36 vs 164 +/- 46 mmHg; p < 0.01) increased, while driving pressure (13 +/- 2 vs 11 +/- 2 cmH(2)O; p < 0.01) and lung ultrasound consolidation score decreased [5 (4-5) vs 2 (1-4); p < 0.01]. EELI decreased ventrally (218 +/- 205 mL; p < 0.01) and increased dorsally (192 +/- 475 mL; p = 0.02), while regional compliance increased in both ventral (11.5 +/- 0.7 vs 12.9 +/- 0.8 mL/cmH(2)O;p< 0.01 ) and dorsal regions (17.1 +/- 1.8 vs 18.8 +/- 1.8 mL/cmH(2)O; p < 0.01). Dorsal distribution of perfusion increased (64.8 +/- 7.3% vs 66.3 +/- 7.2%; p = 0.01). Conclusions: Without increasing airway pressure, a sequential postural recruitment maneuver improves global and regional respiratory mechanics and gas exchange along with a redistribution of EELI from ventral to dorsal lung areas and less consolidation.
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21.
  • Santos, Arnoldo, et al. (författare)
  • Acute Respiratory Distress Syndrome deteriorates pulmonary vascular efficiency and increases cardiac energy wasting in a porcine model.
  • Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
    • Background: Right ventricle failure worsen outcomes in acute respiratory distress syndrome (ARDS). However, the pathophysiology of right ventricle failure and vascular dysfunction in ARDS is not completely understood. In this study we aim to evaluate the effects of early ARDS on pulmonary vascular efficiency for transmission of flow and pressure in an experimental animal model.  Methods: ARDS was induced in 10 pigs (32.5±4.3 kg) combining saline lung-lavages with injurious mechanical ventilation. Pressure and flow sensors were placed at the main pulmonary artery for pulmonary vascular function evaluation, including arterial load parameters, cardiac power and energy transmission ratio.Results: Compared to baseline healthy conditions, ARDS increased pulmonary vascular resistance (199±62 versus 524±154 dyn.s.cm-5, p <0.001), effective arterial elastance (0.65±0.26 versus 1.13±0.36 mmHg/ml, p <0.001) and total hydraulic power (195±60 to 266±87 mW, p =0.015), decreased pulmonary arterial compliance (from 2.34±0.86 to 1.00±0.25 ml/mmHg, p <0.001) and energy transmission ratio (68±15 versus 55±14%, p = 0.014), whereas oscillatory power did not change (17±6 versus 16±6%, p = 0.359).Conclusions: In this experimental ARDS model, an increase in pulmonary arterial load was associated with a higher cardiac power and a decrease in the energy transmission ratio. These results suggest that right ventricle energy consumption is increased and part of this energy is wasted in pulmonary circulation worsening pulmonary vascular efficiency in the early course of ARDS. These findings may help to explain primary mechanisms leading to right ventricle dysfunction in ARDS.
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22.
  • Santos, Arnoldo, et al. (författare)
  • Cyclic Changes of Pulmonary Vascular Mechanics During mechanical ventilation in acute respiratory distress syndrome. A porcine experimental model.
  • Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
    • Objective: To test the hypothesis that acute respiratory syndrome (ARDS) worsens pulmonary vascular mechanics during the respiratory cycle under mechanical ventilation in an animal model.  Design: Experimental study.Setting: Animal research laboratory.Subjects: 6 pigs, 31.7 ± 5.4 kg.Interventions: ARDS was induced by combining saline lung-lavages with injurious mechanical ventilation. Pressure and flow sensors were placed at the main pulmonary artery (PA) and signals were collected simultaneously with airway pressure and flow. Pulmonary vascular mechanics and cardiac function parameters were calculates beat by beat during 2-3 minutes. We designed a novel method to quantify how the calculated variables behave during the whole respiratory cycle, i.e., during expiration and during inspiration. Results are expressed as the mean value during the corresponding phase of the respiratory cycle.Measurements and Main Results: During the whole respiratory cycle and at expiration ARDS decreased SV and arterial compliance while increased mean and pulse PA pressure, effective arterial elastance and Dp/Dtmax when compared to baseline. At baseline and after ARDS, inspiration in positive pressure ventilation caused a decrease in stroke volume (-3±1ml, p<0.001 and -3±1ml, p<0.001), pulmonary mean (-0.5±0.3, p=0.007 and -0.7±0.3mmHg, p=0.002) and pulse pressure (-0.8±0.4, p=0.003 and -1,5±0.7mmHg, p=0.003) and compliance (-0.07±0.04 and -0.04±0.00ml/mmHg, p<0.001) and an increase in resistance (34±13, p=0.001 and 50±32dyn.s.cm-5, p=0.012) and in effective arterial elastance (0.04±0.01, p=0.001 and 0.08±0.04mmHg/ml, p=0.003). ARDS produced a more pronounced inspiratory increase in effective arterial elastance (p=0.041) when compared to baseline. Positive pressure ventilation caused a decrease in Dp/Dtmax at baseline (-15±9mmHg/s, p=0.010) but this was not significant during ARDS (-27±28mmHg/s, p=0.068).  Conclusions: We found in this experimental model that MV induced tidal increase in arterial load and that this effect was higher during ARDS. This finding if transferred to patients, might partly explain the high rate of right heart failure clinically in ARDS.
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23.
  • Santos, Arnoldo, et al. (författare)
  • Effects on Pulmonary Vascular Mechanics of Two Different Lung-Protective Ventilation Strategies in an Experimental Model of Acute Respiratory Distress Syndrome
  • 2017
  • Ingår i: Critical Care Medicine. - 0090-3493 .- 1530-0293. ; 45:11, s. e1157-e1164
  • Tidskriftsartikel (refereegranskat)abstract
    • OBJECTIVES: To compare the effects of two lung-protective ventilation strategies on pulmonary vascular mechanics in early acute respiratory distress syndrome.DESIGN: Experimental study.SETTING: University animal research laboratory.SUBJECTS: Twelve pigs (30.8 ± 2.5 kg).INTERVENTIONS: Acute respiratory distress syndrome was induced by repeated lung lavages and injurious mechanical ventilation. Thereafter, animals were randomized to 4 hours ventilation according to the Acute Respiratory Distress Syndrome Network protocol or to an open lung approach strategy. Pressure and flow sensors placed at the pulmonary artery trunk allowed continuous assessment of pulmonary artery resistance, effective elastance, compliance, and reflected pressure waves. Respiratory mechanics and gas exchange data were collected.MEASUREMENTS AND MAIN RESULTS: Acute respiratory distress syndrome led to pulmonary vascular mechanics deterioration. Four hours after randomization, pulmonary vascular mechanics was similar in Acute Respiratory Distress Syndrome Network and open lung approach: resistance (578 ± 252 vs 626 ± 153 dyn.s/cm; p = 0.714), effective elastance, (0.63 ± 0.22 vs 0.58 ± 0.17 mm Hg/mL; p = 0.710), compliance (1.19 ± 0.8 vs 1.50 ± 0.27 mL/mm Hg; p = 0.437), and reflection index (0.36 ± 0.04 vs 0.34 ± 0.09; p = 0.680). Open lung approach as compared to Acute Respiratory Distress Syndrome Network was associated with improved dynamic respiratory compliance (17.3 ± 2.6 vs 10.5 ± 1.3 mL/cm H2O; p < 0.001), driving pressure (9.6 ± 1.3 vs 19.3 ± 2.7 cm H2O; p < 0.001), and venous admixture (0.05 ± 0.01 vs 0.22 ± 0.03, p < 0.001) and lower mean pulmonary artery pressure (26 ± 3 vs 34 ± 7 mm Hg; p = 0.045) despite of using a higher positive end-expiratory pressure (17.4 ± 0.7 vs 9.5 ± 2.4 cm H2O; p < 0.001). Cardiac index, however, was lower in open lung approach (1.42 ± 0.16 vs 2.27 ± 0.48 L/min; p = 0.005).CONCLUSIONS: In this experimental model, Acute Respiratory Distress Syndrome Network and open lung approach affected pulmonary vascular mechanics similarly. The use of higher positive end-expiratory pressures in the open lung approach strategy did not worsen pulmonary vascular mechanics, improved lung mechanics, and gas exchange but at the expense of a lower cardiac index.
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24.
  • Santos, Arnoldo, et al. (författare)
  • Impact of respiratory cycle during mechanical ventilation on beat-to-beat right ventricle stroke volume estimation by pulmonary artery pulse wave analysis
  • 2024
  • Ingår i: Intensive Care Medicine Experimental. - : Springer. - 2197-425X. ; 12
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: The same principle behind pulse wave analysis can be applied on the pulmonary artery (PA) pressure waveform to estimate right ventricle stroke volume (RVSV). However, the PA pressure waveform might be influenced by the direct transmission of the intrathoracic pressure changes throughout the respiratory cycle caused by mechanical ventilation (MV), potentially impacting the reliability of PA pulse wave analysis (PAPWA). We assessed a new method that minimizes the direct effect of the MV on continuous PA pressure measurements and enhances the reliability of PAPWA in tracking beat-to-beat RVSV.Methods: Continuous PA pressure and flow were simultaneously measured for 2-3 min in 5 pigs using a high-fidelity micro-tip catheter and a transonic flow sensor around the PA trunk, both pre and post an experimental ARDS model. RVSV was estimated by PAPWA indexes such as pulse pressure (SVPP), systolic area (SVSystAUC) and standard deviation (SVSD) beat-to-beat from both corrected and non-corrected PA signals. The reference RVSV was derived from the PA flow signal (SVref).Results: The reliability of PAPWA in tracking RVSV on a beat-to-beat basis was enhanced after accounting for the direct impact of intrathoracic pressure changes induced by MV throughout the respiratory cycle. This was evidenced by an increase in the correlation between SVref and RVSV estimated by PAPWA under healthy conditions: rho between SVref and non-corrected SVSD - 0.111 (0.342), corrected SVSD 0.876 (0.130), non-corrected SVSystAUC 0.543 (0.141) and corrected SVSystAUC 0.923 (0.050). Following ARDS, correlations were SVref and non-corrected SVSD - 0.033 (0.262), corrected SVSD 0.839 (0.077), non-corrected SVSystAUC 0.483 (0.114) and corrected SVSystAUC 0.928 (0.026). Correction also led to reduced limits of agreement between SVref and SVSD and SVSystAUC in the two evaluated conditions.Conclusions: In our experimental model, we confirmed that correcting for mechanical ventilation induced changes during the respiratory cycle improves the performance of PAPWA for beat-to-beat estimation of RVSV compared to uncorrected measurements. This was demonstrated by a better correlation and agreement between the actual SV and the obtained from PAPWA.
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25.
  • Santos, Arnoldo, et al. (författare)
  • The Open Lung Approach Improves Pulmonary Vascular Mechanics in an Experimental Model of Acute Respiratory Distress Syndrome
  • 2017
  • Ingår i: Critical Care Medicine. - 0090-3493 .- 1530-0293. ; 45:3, s. e298-e305
  • Tidskriftsartikel (refereegranskat)abstract
    • OBJECTIVE: To test whether positive end-expiratory pressure consistent with an open lung approach improves pulmonary vascular mechanics compared with higher or lower positive end-expiratory pressures in experimental acute respiratory distress syndrome.DESIGN: Experimental study.SETTING: Animal research laboratory.SUBJECTS: Ten pigs, 35 ± 5.2 kg.INTERVENTIONS: Acute respiratory distress syndrome was induced combining saline lung lavages with injurious mechanical ventilation. The positive end-expiratory pressure level resulting in highest compliance during a decremental positive end-expiratory pressure trial after lung recruitment was determined. Thereafter, three positive end-expiratory pressure levels were applied in a random order: hyperinflation, 6 cm H2O above; open lung approach, 2 cm H2O above; and collapse, 6 cm H2O below the highest compliance level. High fidelity pressure and flow sensors were placed at the main pulmonary artery for measuring pulmonary artery resistance (Z0), effective arterial elastance, compliance, and reflected pressure waves.MEASUREMENTS AND MAIN RESULTS: After inducing acute respiratory distress syndrome, Z0 and effective arterial elastance increased (from 218 ± 94 to 444 ± 115 dyn.s.cm and from 0.27 ± 0.14 to 0.62 ± 0.22 mm Hg/mL, respectively; p < 0.001), vascular compliance decreased (from 2.76 ± 0.86 to 1.48 ± 0.32 mL/mm Hg; p = 0.003), and reflected waves arrived earlier (0.23 ± 0.07 vs 0.14 ± 0.05, arbitrary unit; p = 0.002) compared with baseline. Comparing the three positive end-expiratory pressure levels, open lung approach resulted in the lowest: 1) Z0 (297 ± 83 vs 378 ± 79 dyn.s.cm, p = 0.033, and vs 450 ± 119 dyn.s.cm, p = 0.002); 2) effective arterial elastance (0.37 ± 0.08 vs 0.50 ± 0.15 mm Hg/mL, p = 0.04, and vs 0.61 ± 0.12 mm Hg/mL, p < 0.001), and 3) reflection coefficient (0.35 ± 0.17 vs 0.48 ± 0.10, p = 0.024, and vs 0.53 ± 0.19, p = 0.005), comparisons with hyperinflation and collapse, respectively.CONCLUSIONS: In this experimental setting, positive end-expiratory pressure consistent with the open lung approach resulted in the best pulmonary vascular mechanics compared with higher or lower positive end-expiratory pressure settings.
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26.
  • Solà, Josep, et al. (författare)
  • Non-invasive monitoring of central blood pressure by electrical impedance tomography : first experimental evidence
  • 2011
  • Ingår i: Medical and Biological Engineering and Computing. - : Springer Science and Business Media LLC. - 0140-0118 .- 1741-0444. ; 49:4, s. 409-415
  • Tidskriftsartikel (refereegranskat)abstract
    • There is a strong clinical demand for devices allowing continuous non-invasive monitoring of central blood pressure (BP). In the state of the art a new family of techniques providing BP surrogates based on the measurement of the so-called pulse wave velocity (PWV) has been proposed, eliminating the need for inflation cuffs. PWV is defined as the velocity at which pressure pulses propagate along the arterial wall. However, no technique to assess PWV within central arteries in a fully unsupervised manner has been proposed so far. In this pilot study, we provide first experimental evidence that electrical impedance tomography (EIT) is capable of measuring pressure pulses directly within the descending aorta. To obtain a wide range of BP values, we administrated noradrenalin and nitroglycerine to an anesthetized pig under mechanical ventilation. An arterial line was inserted into the ascending aorta for measuring reference BP. EIT images were generated from 32 impedance electrodes placed around the chest at the level of the axilla. Regions of Interest (ROI) such as the descending aorta and the lungs were automatically identified by a novel time-based processing algorithm as the respective EIT pixels representing these structures. The correct positions of these ROIs were confirmed by bolus injections of highly conductive concentrated saline into the right heart and into the ascending aorta. Aortic pulse transit time (PTT) values were determined as the delay between the opening of the aortic valve (obtained from arterial line) and the arrival of pressure pulses at the aortic ROI within the EIT plane. For 11 experimental conditions, with mean BP ranging from 73 to 141 mmHg, strongly significant correlation (r = -0.97, P < 0.00001) between central BP and aortic PTT was observed, suggesting that EIT-derived aortic PTT is a potential non-invasive surrogate of central BP.
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27.
  • Suarez-Sipmann, Fernando, et al. (författare)
  • Corrections of Enghoffs dead space formula for shunt effects still overestimate Bohr's dead space
  • 2013
  • Ingår i: Respiratory Physiology & Neurobiology. - : Elsevier BV. - 1569-9048 .- 1878-1519. ; 189:1, s. 99-105
  • Tidskriftsartikel (refereegranskat)abstract
    • Dead space ratio is determined using Enghoffs modification (VDB-E/V-T) of Bohr's formula (V-DBohr/V-T) in which arterial is used as a surrogate of alveolar PCO2. In presence of intrapulmonary shunt Enghoffs approach overestimates dead space. In 40 lung-lavaged pigs we evaluated the Kuwabara's and Niklason's algorithms to correct for shunt effects and hypothesized that corrected VDB-E/V-T should provide similar values as V-DBohr/V-T. We analyzed 396 volumetric capnograms and arterial and mixed-venous blood samples to calculate V-DBohr/V-T and VDB-E/V-T. Thereafter, we corrected the latter for shunt effects using Kuwabara's (K) VDB-E/V-T and Niklason's (N) VDB-E/V-T algorithms. Uncorrected VDB-E/V-T (mean +/- SD of 0.70 +/- 0.10) overestimated V-DBohr/V-T (0.59 +/- 0.12) (p < 0.05), over the entire range of shunts. Mean (K) VDB-E/V-T was significantly higher than V-DBor/V-T (0.67 +/- 0.08, bias 0.085, limits of agreement 0.232 to 0.085; p< 0.05) whereas (N)VDB-E/V-T showed a better correction for shunt effects (0.64 +/- 0.09, bias 0.048, limits of agreement -0.168 to 0.072; p < 0.05). Neither Kuwabara's nor Niklason's algorithms were able to correct EnghofFs dead space formula for shunt effects. 
  •  
28.
  • Suarez Sipmann, Fernando, et al. (författare)
  • Heart-lung interactions in acute respiratory distress syndrome : pathophysiology, detection and management strategies
  • 2018
  • Ingår i: Annals of Translational Medicine. - : AME PUBL CO. - 2305-5839 .- 2305-5847. ; 6:2
  • Forskningsöversikt (refereegranskat)abstract
    • Acute respiratory distress syndrome (ARDS) is the most severe form of acute respiratory failure characterized by diffuse alveolar and endothelial damage. The severe pathophysiological changes in lung parenchyma and pulmonary circulation together with the effects of positive pressure ventilation profoundly affect heart lung interactions in ARDS. The term pulmonary vascular dysfunction (PVD) refers to the specific involvement of the vascular compartment in ARDS and is expressed clinically by an increase in pulmonary arterial (PA) pressure and pulmonary vascular resistance both affecting right ventricular (RV) afterload. When severe, PVD can lead to RV failure which is associated to an increased mortality. The effect of PVD on RV function is not only a consequence of increased pulmonary vascular resistance as afterload is a much more complex phenomenon that includes all factors that oppose efficient ventricular ejection. Impaired pulmonary vascular mechanics including increased arterial elastance and augmented wave-reflection phenomena are commonly seen in ARDS and can additionally affect RV afterload. The use of selective pulmonary vasodilators and lung protective mechanical ventilation strategies are therapeutic interventions that can ameliorate PVD. Prone positioning and the open lung approach (OLA) are especially attractive strategies to improve PVD due to their effects on increasing functional lung volume. In this review we will describe some pathophysiological aspects of heart-lung interactions during the ventilatory support of ARDS, its clinical assessment and discuss therapeutic interventions to prevent the occurrence and progression of PVD and RV failure.
  •  
29.
  • Suarez-Sipmann, Fernando, et al. (författare)
  • Monitoring Expired CO2 Kinetics to Individualize Lung-Protective Ventilation in Patients With the Acute Respiratory Distress Syndrome
  • 2021
  • Ingår i: Frontiers in Physiology. - : Frontiers Media S.A.. - 1664-042X. ; 12
  • Forskningsöversikt (refereegranskat)abstract
    • Mechanical ventilation (MV) is a lifesaving supportive intervention in the management of acute respiratory distress syndrome (ARDS), buying time while the primary precipitating cause is being corrected. However, MV can contribute to a worsening of the primary lung injury, known as ventilation-induced lung injury (VILI), which could have an important impact on outcome. The ARDS lung is characterized by diffuse and heterogeneous lung damage and is particularly prone to suffer the consequences of an excessive mechanical stress imposed by higher airway pressures and volumes during MV. Of major concern is cyclic overdistension, affecting those lung segments receiving a proportionally higher tidal volume in an overall reduced lung volume. Theoretically, healthier lung regions are submitted to a larger stress and cyclic deformation and thus at high risk for developing VILI. Clinicians have difficulties in detecting VILI, particularly cyclic overdistension at the bedside, since routine monitoring of gas exchange and lung mechanics are relatively insensitive to this mechanism of VILI. Expired CO2 kinetics integrates relevant pathophysiological information of high interest for monitoring. CO2 is produced by cell metabolism in large daily quantities. After diffusing to tissue capillaries, CO2 is transported first by the venous and then by pulmonary circulation to the lung. Thereafter diffusing from capillaries to lung alveoli, it is finally convectively transported by lung ventilation for its elimination to the atmosphere. Modern readily clinically available sensor technology integrates information related to pulmonary ventilation, perfusion, and gas exchange from the single analysis of expired CO2 kinetics measured at the airway opening. Current volumetric capnography (VCap), the representation of the volume of expired CO2 in one single breath, informs about pulmonary perfusion, end-expiratory lung volume, dead space, and pulmonary ventilation inhomogeneities, all intimately related to cyclic overdistension during MV. Additionally, the recently described capnodynamic method provides the possibility to continuously measure the end-expiratory lung volume and effective pulmonary blood flow. All this information is accessed non-invasively and breath-by-breath helping clinicians to personalize ventilatory settings at the bedside and minimize overdistension and cyclic deformation of lung tissue.
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30.
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31.
  • Suarez-Sipmann, Fernando, et al. (författare)
  • Use of dynamic compliance for open lung positive end-expiratory pressure titration in an experimental study
  • 2007
  • Ingår i: Critical Care Medicine. - 0090-3493 .- 1530-0293. ; 35:1, s. 214-221
  • Tidskriftsartikel (refereegranskat)abstract
    • Objective: We tested whether the continuous monitoring of dynamic compliance could become a useful bedside tool for detecting the beginning of collapse of a fully recruited lung. Design: Prospective laboratory animal investigation. Setting: Clinical physiology research laboratory, University of Uppsala, Sweden. Subjects: Eight pigs submitted to repeated lung lavages. Interventions: Lung recruitment maneuver, the effect of which was confirmed by predefined oxygenation, lung mechanics, and computed tomography scan criteria, was followed by a positive end-expiratory pressure (PEEP) reduction trial in a volume control mode with a tidal volume of 6 mL/kg. Every 10 mins, PEEP was reduced in steps of 2 cm H2O starting from 24 cm H2O. During PEEP reduction, lung collapse was defined by the maximum dynamic compliance value after which a first measurable decrease occurred. Open lung PEEP according to dynamic compliance was then defined as the level of PEEP before the point of collapse. This value was compared with oxygenation (PaO2) and CT scans. Measurements and Main Results: PaO2 and dynamic compliance were monitored continuously, whereas computed tomography scans were obtained at the end of each pressure step. Collapse defined by dynamic compliance occurred at a PEEP of 14 cm H2O. This level coincided with the oxygenation-based collapse point when also shunt started to increase and occurred one step before the percentage of nonaerated tissue on the computed tomography exceeded 5%. Open lung PEEP was thus at 16 cm H2O, the level at which oxygenation and computed tomography scan confirmed a fully open, not yet collapsed lung condition. Conclusions: In this experimental model, the continuous monitoring of dynamic compliance identified the beginning of collapse after lung recruitment. These findings were confirmed by oxygenation and computed tomography scans. This method might become a valuable bedside tool for identifying the level of PEEP that prevents end-expiratory collapse.
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32.
  • Suarez-Sipmann, Fernando, et al. (författare)
  • Volumetric capnography : the time has come
  • 2014
  • Ingår i: Current Opinion in Critical Care. - 1070-5295 .- 1531-7072. ; 20:3, s. 333-339
  • Forskningsöversikt (refereegranskat)abstract
    • Purpose of review This review article summarizes the recent advances in electrical impedance tomography (EIT) related to cardiopulmonary imaging and monitoring on the background of the 30-year development of this technology. Recent findings EIT is expected to become a bedside tool for monitoring and guiding ventilator therapy. In this context, several studies applied EIT to determine spatial ventilation distribution during different ventilation modes and settings. EIT was increasingly combined with other signals, such as airway pressure, enabling the assessment of regional respiratory system mechanics. EIT was for the first time used prospectively to define ventilator settings in an experimental and a clinical study. Increased neonatal and paediatric use of EIT was noted. Only few studies focused on cardiac function and lung perfusion. Advanced radiological imaging techniques were applied to assess EIT performance in detecting regional lung ventilation. New approaches to improve the quality of thoracic EIT images were proposed. EIT is not routinely used in a clinical setting, but the interest in EIT is evident. The major task for EIT research is to provide the clinicians with guidelines how to conduct, analyse and interpret EIT examinations and combine them with other medical techniques so as to meaningfully impact the clinical decision-making.
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33.
  • Tusman, Gerardo, et al. (författare)
  • Advanced Uses of Pulse Oximetry for Monitoring Mechanically Ventilated Patients
  • 2017
  • Ingår i: Anesthesia and Analgesia. - 0003-2999 .- 1526-7598. ; 124:1, s. 62-71
  • Tidskriftsartikel (refereegranskat)abstract
    • Pulse oximetry is an undisputable standard of care in clinical monitoring. It combines a spectrometer to detect hypoxemia with a plethysmograph for the diagnosis, monitoring, and follow-up of cardiovascular diseases. These pulse oximetry capabilities are extremely useful for assessing the respiratory and circulatory status and for monitoring of mechanically ventilated patients. On the one hand, the key spectrography-derived function of pulse oximetry is to evaluate a patient's gas exchange that results from a particular ventilatory treatment by continuously and noninvasively measuring arterial hemoglobin saturation (Spo(2)). This information helps to maintain patients above the hypoxemic levels, leading to appropriate ventilator settings and inspired oxygen fractions. However, whenever higher than normal oxygen fractions are used, Spo(2) can mask existing oxygenation defects in ventilated patients. This limitation, resulting from the S shape of the oxyhemoglobin saturation curve, can be overcome by reducing the oxygen fraction delivered to the patient in a controlled and stepwise manner. This results in a Spo(2)/Fio(2) diagram, which allows a rough characterization of a patient's gas exchange, shunt, and the amount of lung area with a low ventilation/perfusion ratio without the need of blood sampling. On the other hand, the photoplethysmography-derived oximeter function has barely been exploited for the purpose of monitoring hemodynamics in mechanically ventilated patients. The analysis of the photoplethysmography contour provides useful real-time and noninvasive information about the interaction of heart and lungs during positive pressure ventilation. These hemodynamic monitoring capabilities are related to both the assessment of preload dependency mainly by analyzing the breath-by-breath variation of the photoplethysmographic signals and the analysis of arterial impedance, Which examines the changes in the plethysmographic amplitude, contour, and derived indexes. In this article, we present and describe these extended monitoring capabilities and propose a more holistic monitoring concept that takes advantage of these advanced uses of pulse oximetry in the monitoring of ventilated patients. Today's monitors need to be improved if such novel functionalities were to be offered for clinical use. Future developments and clinical evaluations are needed to establish the true potential of these advanced monitoring uses of pulse oximetry.
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34.
  • Tusman, Gerardo, et al. (författare)
  • Bohr Dead Space Calculation In Response
  • 2012
  • Ingår i: Anesthesia and Analgesia. - 0003-2999 .- 1526-7598. ; 115:6, s. 1472-1473
  • Tidskriftsartikel (refereegranskat)
  •  
35.
  •  
36.
  • Tusman, Gerardo, et al. (författare)
  • Dead space during one-lung ventilation
  • 2015
  • Ingår i: Current Opinion in Anaesthesiology. - 0952-7907 .- 1473-6500. ; 28:1, s. 10-17
  • Forskningsöversikt (refereegranskat)abstract
    • Purpose of review Describe the importance of monitoring dead space during thoracic surgery, specifically during one-lung ventilation. Recent findings The concept of dead space has gained renewed interest among anesthesiologists ever since breath-by-breath measurement by volumetric capnography became available. Monitoring dead space during thoracic surgery assesses the ventilatory deficiencies related to increases in instrumental, airway and/or alveolar dead space, when ventilating patients with positive pressure and double-lumen tubes. Another interesting use of such monitoring is to detect ventilator-induced lung injury due to tidal overdistension. This type of injury threatens the fragile lungs especially during one-lung ventilation and can clinically be recognized as an increase in airway and alveolar dead space above normal values. To date, lung protective ventilation is based on the use of low tidal volumes and airway pressures to decrease overdistension. It has been shown to reduce the incidence of postoperative pulmonary complications after thoracic surgeries. However, such a ventilatory strategy impairs ventilation and induces hypercapnia due to increases in dead space. Therefore, continuous assessment of dead space is helpful in guiding ventilation and avoiding overdistension while maintaining the elimination of CO2 during thoracic surgery sufficiently high. Summary Monitoring dead space helps anesthesiologists monitor the status of the lung and find appropriate ventilatory settings during thoracic surgeries.
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37.
  • Tusman, Gerardo, et al. (författare)
  • Lung recruitment and positive end-expiratory pressure have different effects on CO2 elimination in healthy and sick lungs
  • 2010
  • Ingår i: Anesthesia and Analgesia. - 0003-2999 .- 1526-7598. ; 111:4, s. 968-977
  • Tidskriftsartikel (refereegranskat)abstract
    • BACKGROUND: We studied the effects that the lung recruitment maneuver (RM) and positive end-expiratory pressure (PEEP) have on the elimination of CO(2) per breath (Vtco(2,br)). METHODS: In 7 healthy and 7 lung-lavaged pigs at constant ventilation, PEEP was increased from 0 to 18 cm H(2)O and then decreased to 0 in steps of 6 cm H(2)O every 10 minutes. Cycling RMs with plateau pressure/PEEP of 40/20 (healthy) and 50/25 (lavaged) cm H(2)O were applied for 2 minutes between 18-PEEP steps. Volumetric capnography, respiratory mechanics, blood gas, and hemodynamic data were recorded. RESULTS: In healthy lungs before the RM, Vtco(2,br) was inversely proportional to PEEP decreasing from 4.0 (3.6-4.4) mL (median and interquartile range) at 0-PEEP to 3.1 (2.8-3.4) mL at 18-PEEP (P < 0.05). After the RM, Vtco(2,br) increased from 3.3 (3-3.6) mL at 18-PEEP to 4.0 (3.5-4.5) mL at 0-PEEP (P < 0.05). In lavaged lungs before the RM, Vtco(2,br) increased initially from 2.0 (1.7-2.3) mL at 0-PEEP to 2.6 (2.2-3) mL at 12-PEEP (P < 0.05) but then decreased to 2.4 (2-2.8) mL when PEEP was increased further to 18 cm H(2)O (P < 0.05). After the RM, the highest Vtco(2,br) of 2.9 (2.1-3.7) mL was observed at 12-PEEP and then decreased to 2.5 (1.9-3.1) mL at 0-PEEP (P < 0.05). Vtco(2,br) was directly related to changes in lung perfusion, the area of gas exchange, and alveolar ventilation but inversely related to changes in dead space. CONCLUSIONS: CO(2) elimination by the lungs was dependent on PEEP and recruitment and showed major differences between healthy and lavaged lungs.
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38.
  • Tusman, Gerardo, et al. (författare)
  • Model fitting of volumetric capnograms improves calculations of airway dead space and slope of phase III
  • 2009
  • Ingår i: Journal of clinical monitoring and computing. - : Springer Science and Business Media LLC. - 1387-1307 .- 1573-2614. ; 23:4, s. 197-206
  • Tidskriftsartikel (refereegranskat)abstract
    • Background This study assessed the performance of a Functional Approximation based on a Levenberg-Marquardt Algorithm (FA-LMA) to calculate airway dead space (VDaw) and the slope of phase III (S III) from capnograms. Methods We performed mathematical simulations to test the effect of noises on the calculation of VDaw and S III. Data from ten mechanically ventilated patients at 0, 5 and 10 cmH2O of PEEP were also studied. FA-LMA was compared with the traditional Fowler’s method (FM). Results Simulations showed that: (1) The FM determined VDaw with accuracy only if the capnogram approximated a symmetrical curve (S III = 0). When capnograms became asymmetrical (S III > 0), the FM underestimated VDaw (−3.1% to −0.9%). (2) When adding noises on 800 capnograms, VDaw was underestimated whenever the FM was used thereby creating a bias between −5.54 and −1.28 ml at standard deviations (SD) of 0.1–1.8 ml (P < 0.0001). FA-LMA calculations of VDaw were close to the simulated values with the bias ranging from −0.21 to 0.16 ml at SD from 0.1 to 0.4 ml. The FM overestimated S III and showed more bias (0.0041–0.0078 mmHg/ml, P < 0.0001) than the FA-LMA (0.0002–0.0030 mmHg/ml). When calculating VDaw from patients, variability was less with the FA-LMA leading to mean variation coefficients of 0.0102, 0.0111 and 0.0123 compared to the FM (0.0243, 0.0247 and 0.0262, P < 0.001) for 0, 5 and 10 cmH2O of PEEP, respectively. The FA-LMA also showed less variability in S III with mean variation coefficients of 0.0739, 0.0662 and 0.0730 compared to the FM (0.1379, 0.1208 and 0.1246, P < 0.001) for 0, 5 and 10 cmH2O of PEEP, respectively. Conclusions The Functional Approxi- mation based on a Levenberg-Marquardt Algorithm showed less bias and dispersion compared to the traditional Fowler’s method when calculating VDaw and S III.
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39.
  • Tusman, Gerardo, et al. (författare)
  • Monitoring dead space during recruitment and PEEP titration in an experimental model
  • 2006
  • Ingår i: Intensive Care Medicine. - : Springer Science and Business Media LLC. - 0342-4642 .- 1432-1238. ; 32:11, s. 1863-1871
  • Tidskriftsartikel (refereegranskat)abstract
    • Objective: To test the usefulness of dead space for determining open-lung PEEP, the lowest PEEP that prevents lung collapse after a lung recruitment maneuver. Design: Prospective animal study. Setting: Department of Clinical Physiology, University of Uppsala, Sweden. Subjects: Eight lung-lavaged pigs. Interventions: Animals were ventilated using constant flow mode with VT of 6 ml/kg, respiratory rate of 30 bpm, inspiratory-to-expiratory ratio of 1 : 2, and FiO(2) of 1. Baseline measurements were performed at 6 cmH(2)O of PEEP. PEEP was increased in steps of 6 cmH(2)O from 6 to 24 cmH(2)O. Recruitment maneuver was achieved within 2 min at pressure levels of 60/30 cmH(2)O for Peak/PEEP. PEEP was decreased from 24 to 6 cmH(2)O in steps of 2 cmH(2)O and then to 0 cmH(2)O. Each PEEP step was maintained for 10 min. Measurements and results: Alveolar dead space (VDalv), the ratio of alveolar dead space to alveolar tidal volume (VDalv/VTalv), and the arterial to end-tidal PCO2 difference (Pa-ETCO2) showed a good correlation with PaO2, normally aerated areas, and non-aerated CT areas in all animals (minimum-maximum r(2) = 0.83-0.99; p < 0.01). Lung collapse (non-aerated tissue > 5%) started at 12 cmH(2)O PEEP; hence, open-lung PEEP was established at 14 cmH(2)O. The receiver operating characteristics curve demonstrated a high specificity and sensitivity of VDalv (0.89 and 0.90), VDalv/VTalv (0.82 and 1.00), and Pa-ETCO2 (0.93 and 0.95) for detecting lung collapse. Conclusions: Monitoring of dead space was useful for detecting lung collapse and for establishing open-lung PEEP after a recruitment maneuver.
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40.
  • Tusman, Gerardo, et al. (författare)
  • Multimodal non-invasive monitoring to apply an open lung approach strategy in morbidly obese patients during bariatric surgery
  • 2020
  • Ingår i: Journal of clinical monitoring and computing. - : SPRINGER HEIDELBERG. - 1387-1307 .- 1573-2614. ; 34:5, s. 1015-1024
  • Tidskriftsartikel (refereegranskat)abstract
    • To evaluate the use of non-invasive variables for monitoring an open-lung approach (OLA) strategy in bariatric surgery. Twelve morbidly obese patients undergoing bariatric surgery received a baseline protective ventilation with 8 cmH(2)O of positive-end expiratory pressure (PEEP). Then, the OLA strategy was applied consisting in lung recruitment followed by a decremental PEEP trial, from 20 to 8 cmH(2)O, in steps of 2 cmH(2)O to find the lung's closing pressure. Baseline ventilation was then resumed setting open lung PEEP (OL-PEEP) at 2 cmH(2)O above this pressure. The multimodal non-invasive variables used for monitoring OLA consisted in pulse oximetry (SpO(2)), respiratory compliance (Crs), end-expiratory lung volume measured by a capnodynamic method (EELVCO2), and esophageal manometry. OL-PEEP was detected at 15.9 +/- 1.7 cmH(2)O corresponding to a positive end-expiratory transpulmonary pressure (P-L,P-ee) of 0.9 +/- 1.1 cmH(2)O. ROC analysis showed that SpO(2) was more accurate (AUC 0.92, IC95% 0.87-0.97) than Crs (AUC 0.76, IC95% 0.87-0.97) and EELVCO2 (AUC 0.73, IC95% 0.64-0.82) to detect the lung's closing pressure according to the change of P-L,P-ee from positive to negative values. Compared to baseline ventilation with 8 cmH(2)O of PEEP, OLA increased EELVCO2 (1309 +/- 517 vs. 2177 +/- 679 mL) and decreased driving pressure (18.3 +/- 2.2 vs. 10.1 +/- 1.7 cmH(2)O), estimated shunt (17.7 +/- 3.4 vs. 4.2 +/- 1.4%), lung strain (0.39 +/- 0.07 vs. 0.22 +/- 0.06) and lung elastance (28.4 +/- 5.8 vs. 15.3 +/- 4.3 cmH(2)O/L), respectively; all p < 0.0001. The OLA strategy can be monitored using noninvasive variables during bariatric surgery. This strategy decreased lung strain, elastance and driving pressure compared with standard protective ventilatory settings. Clinical trial number NTC03694665.
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41.
  • Tusman, Gerardo, et al. (författare)
  • Noninvasive Monitoring of Lung Recruitment Maneuvers in Morbidly Obese Patients : The Role of Pulse Oximetry and Volumetric Capnography
  • 2014
  • Ingår i: Anesthesia and Analgesia. - : Ovid Technologies (Wolters Kluwer Health). - 0003-2999 .- 1526-7598. ; 118:1, s. 137-144
  • Tidskriftsartikel (refereegranskat)abstract
    • BACKGROUND: We conducted this study to determine whether pulse oximetry and volumetric capnography (VCap) can determine the opening and closing pressures of lungs of anesthetized morbidly obese patients. METHODS: Twenty morbidly obese patients undergoing laparoscopic bariatric surgery with capnoperitoneum were studied. A lung recruitment maneuver was performed in pressure control ventilation as follows: (1) During an ascending limb, the lungs' opening pressure was detected. After increasing positive end-expiratory pressure (PEEP) from 8 to 16 cm H2O, fraction of inspired oxygen (Fio(2)) was decreased until pulse oximetric arterial saturation (Spo(2)) was <92%. Thereafter, end-inspiratory pressure was increased in steps of 2 cm H2O, from 36 to a maximum of 50 cm H2O. The opening pressure was attained when Spo(2) exceeded 97%. (2) During a subsequent decreasing limb, the lungs' closing pressure was identified. PEEP was decreased from 22 to 10 cm H2O in steps of 2 cm H2O. The closing pressure was determined as the PEEP value at which respiratory compliance decreased from its maximum value. We continuously recorded lung mechanics, Spo(2), and VCap. RESULTS: The lungs' opening pressures were detected at 44 (4) cm H2O (median and interquartile range) and the closing pressure at 14 (2) cm H2O. Therefore, the level of PEEP that kept the lungs without collapse was found to be 16 (3) cm H2O. Using respiratory compliance as a reference, receiver operating characteristic analysis showed that Spo(2) (area under the curve [AUC] 0.80 [SE 0.07], sensitivity 0.65, and specificity 0.94), the elimination of CO2 per breath (AUC 0.91 [SE 0.05], sensitivity 0.85, and specificity 0.98), and Bohr's dead space (AUC 0.83 [SE 0.06], sensitivity 0.70, and specificity 0.95] were relatively accurate for detecting lung collapse during the decreasing limb of a recruitment maneuver. CONCLUSIONS: Lung recruitment in morbidly obese patients could be effectively monitored by combining noninvasive pulse oximetry and VCap. Spo(2), the elimination of CO2, and Bohr's dead space detected the individual's opening and closing pressures.
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42.
  • Tusman, Gerardo, et al. (författare)
  • Perioperative Continuous Noninvasive Cardiac Output Monitoring in Cardiac Surgery Patients by a Novel Capnodynamic Method
  • 2022
  • Ingår i: Journal of Cardiothoracic and Vascular Anesthesia. - : Elsevier. - 1053-0770 .- 1532-8422. ; 36:8, s. 2900-2907
  • Tidskriftsartikel (refereegranskat)abstract
    • ObjectivesTo test the clinical performance of a novel continuous noninvasive cardiac output (CO) monitoring based on expired carbon dioxide kinetics in cardiac surgery patients.DesignA prospective feasibility pragmatic clinical study.SettingA single-center, large community hospital.ParticipantsThirty-two patients undergoing cardiac surgery were studied during the intraoperative (before cardiopulmonary bypass) and postoperative (in the intensive care unit before extubation) periods.InterventionsCO was measured simultaneously by the continuous capnodynamic method and by transpulmonary thermodilution during changes in the patient's hemodynamic and/or respiratory conditions.Measurements and Main ResultsThe current recommended comparative statistics for CO measurement methods were analyzed, including bias, precision, and percentage error obtained from Bland-Altman analysis, and concordance between methods obtained from the four-quadrant plot analysis to evaluate the trending ability. Bias ± limits of agreement and percentage error were –0.6 (–1.9 to +0.8; 95% CI of 3.73-5.25) L/min and 31% (n = 147 measurements) for the intraoperative period, –0.8 (–2.4 to +0.9; 95% CI of 3.03-5.21) L/min and 41% (n = 66) for the postoperative period, and –0.6 (–2.1 to +0.8; 95% CI of 3.74-5.00) L/min and 34% (n = 213) for the pooled data. The trending analysis obtained a concordance of 82% (n = 65) for the intraoperative and 71% (n = 24) for the early postoperative periods. Aggregation of both data sets gave a concordance of 79% (n = 89).ConclusionsThe continuous capnodynamic method was reliable and in good agreement with the reference method, and had an accuracy and trending ability good enough to make it a possible future alternative for hemodynamic monitoring in the studied population of elective adult cardiac surgery patients.
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43.
  • Tusman, Gerardo, et al. (författare)
  • Photoplethysmographic characterization of vascular tone mediated changes in arterial pressure : an observational study
  • 2019
  • Ingår i: Journal of clinical monitoring and computing. - : SPRINGER HEIDELBERG. - 1387-1307 .- 1573-2614. ; 33:5, s. 815-824
  • Tidskriftsartikel (refereegranskat)abstract
    • To determine whether a classification based on the contour of the photoplethysmography signal (PPGc) can detect changes in systolic arterial blood pressure (SAP) and vascular tone. Episodes of normotension (SAP 90-140 mmHg), hypertension (SAP > 140 mmHg) and hypotension (SAP < 90 mmHg) were analyzed in 15 cardiac surgery patients. SAP and two surrogates of the vascular tone, systemic vascular resistance (SVR) and vascular compliance (Cvasc = stroke volume/pulse pressure) were compared with PPGc. Changes in PPG amplitude (foot-to-peak distance) and dicrotic notch position were used to define 6 classes taking class III as a normal vascular tone with a notch placed between 20 and 50% of the PPG amplitude. Class I-to-II represented vasoconstriction with notch placed > 50% in a small PPG, while class IV-to-VI described vasodilation with a notch placed < 20% in a tall PPG wave. 190 datasets were analyzed including 61 episodes of hypertension [SAP = 159 (151-170) mmHg (median 1st-3rd quartiles)], 84 of normotension, SAP = 124 (113-131) mmHg and 45 of hypotension SAP = 85(80-87) mmHg. SAP were well correlated with SVR (r = 0.78, p < 0.0001) and Cvasc (r = 0.84, p < 0.0001). The PPG-based classification correlated well with SAP (r = - 0.90, p < 0.0001), SVR (r = - 0.72, p < 0.0001) and Cvasc (r = 0.82, p < 0.0001). The PPGc misclassified 7 out of the 190 episodes, presenting good accuracy (98.4% and 97.8%), sensitivity (100% and 94.9%) and specificity (97.9% and 99.2%) for detecting episodes of hypotension and hypertension, respectively. Changes in arterial pressure and vascular tone were closely related to the proposed classification based on PPG waveform. Clinical Trial Registration NTC02854852.
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44.
  • Tusman, Gerardo, et al. (författare)
  • Positive end-expiratory pressure individualization guided by continuous end-expiratory lung volume monitoring during laparoscopic surgery
  • 2022
  • Ingår i: Journal of clinical monitoring and computing. - : Springer Nature. - 1387-1307 .- 1573-2614. ; 36:5, s. 1557-1567
  • Tidskriftsartikel (refereegranskat)abstract
    • To determine whether end-expiratory lung volume measured with volumetric capnography (EELVCO2) can individualize positive end-expiratory pressure (PEEP) setting during laparoscopic surgery. We studied patients undergoing laparoscopic surgery subjected to Fowler (F-group; n = 20) or Trendelenburg (T-group; n = 20) positions. EELVCO2 was measured at 0 degrees supine (baseline), during capnoperitoneum (CP) at 0 degrees supine, during CP with Fowler (head up + 20 degrees) or Trendelenburg (head down - 30 degrees) positions and after CP back to 0 degrees supine. PEEP was adjusted to preserve baseline EELVCO2 during and after CP. Baseline EELVCO2 was statistically similar to predicted FRC in both groups. At supine and CP, EELVCO2 decreased from baseline values in F-group [median and IQR 2079 (768) to 1545 (725) mL; p = 0.0001] and in T-group [2164 (789) to 1870 (940) mL; p = 0.0001]. Change in body position maintained EELVCO2 unchanged in both groups. PEEP adjustments from 5.6 (1.1) to 10.0 (2.5) cmH(2)O in the F-group (p = 0.0001) and from 5.6 (0.9) to 10.0 (2.6) cmH(2)O in T-group (p = 0.0001) were necessary to reach baseline EELVCO2 values. EELVCO2 increased close to baseline with PEEP in the F-group [1984 (600) mL; p = 0.073] and in the T-group [2175 (703) mL; p = 0.167]. After capnoperitoneum and back to 0 degrees supine, PEEP needed to maintain EELVCO2 was similar to baseline PEEP in F-group [5.9 (1.8) cmH(2)O; p = 0.179] but slightly higher in the T-group [6.5 (2.2) cmH(2)O; p = 0.006]. Those new PEEP values gave EELVCO2 similar to baseline in the F-group [2039 (980) mL; p = 0.370] and in the T-group [2150 (715) mL; p = 0.881]. Breath-by-breath noninvasive EELVCO2 detected changes in lung volume induced by capnoperitoneum and body position and was useful to individualize the level of PEEP during laparoscopy. Trial registry: Clinicaltrials.gov NCT03693352. Protocol started 1st October 2018.
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45.
  • Tusman, Gerardo, et al. (författare)
  • Postural lung recruitment assessed by lung ultrasound in mechanically ventilated children
  • 2017
  • Ingår i: Critical Ultrasound Journal. - : SPRINGER-VERLAG ITALIA SRL. - 2036-3176 .- 2036-7902. ; 9
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Atelectasis is a common finding in mechanically ventilated children with healthy lungs. This lung collapse cannot be overcome using standard levels of positive end-expiratory pressure (PEEP) and thus for only individualized lung recruitment maneuvers lead to satisfactory therapeutic results. In this short communication, we demonstrate by lung ultrasound images (LUS) the effect of a postural recruitment maneuver (P-RM, i.e., a ventilatory strategy aimed at reaerating atelectasis by changing body position under constant ventilation). Results: Data was collected in the operating room of the Hospital Privado de Comunidad, Mar del Plata, Argentina. Three anesthetized children undergoing mechanical ventilation at constant settings were sequentially subjected to the following two maneuvers: (1) PEEP trial in the supine position PEEP was increased to 10 cmH(2)O for 3 min and then decreased to back to baseline. (2) P-RM patient position was changed from supine to the left and then to the right lateral position for 90 s each before returning to supine. The total P-RM procedure took approximately 3 min. LUS in the supine position showed similar atelectasis before and after the PEEP trial. Contrarily, atelectasis disappeared in the non-dependent lung when patients were placed in the lateral positions. Both lungs remained atelectasis free even after returning to the supine position. Conclusions: We provide LUS images that illustrate the concept and effects of postural recruitment in children. This maneuver has the advantage of achieving recruitment effects without the need to elevate airways pressures.
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46.
  • Tusman, Gerardo, et al. (författare)
  • Pulmonary blood flow generates cardiogenic oscillations
  • 2009
  • Ingår i: Respiratory Physiology & Neurobiology. - : Elsevier BV. - 1569-9048 .- 1878-1519. ; 167:3, s. 247-254
  • Tidskriftsartikel (refereegranskat)abstract
    • Cardiogenic oscillations are small waves produced by heartbeats, which are superimposed on the pressure and flow signals at the airway opening. The aim of this study was to investigate the role of the two main factors believed to generate these oscillations: (1) contact between heart and lungs and (2) pulmonary blood flow. We studied 15 heart surgery patients on cardiopulmonary bypass so both factors could be manipulated independently. At minimal heart–lung contact pressure and flow oscillations were larger than during maximal contact (1.20 ± 0.17 cmH2O and 2.36 ± 0.08 L min−1 vs 0.92 ± 0.15 cmH2O and 1.78 ± 0.26 L min−1, mean ± SD, p < 0.05). Cardiogenic oscillations for pressure and flow were smaller at 50% compared to 100% pulmonary blood flow (0.80 ± 0.12 cmH2O and 1.56 ± 0.34 L min−1 vs 1.19 ± 0.14 cmH2O and 2.38 ± 0.19 L min−1). We conclude that the amount of pulmonary blood flow and not the contact between heart and lungs is the main factor determining the amplitude of cardiogenic oscillations.
  •  
47.
  • Tusman, Gerardo, et al. (författare)
  • Rationale of Dead Space Measurement by Volumetric Capnography
  • 2012
  • Ingår i: Anesthesia and Analgesia. - 0003-2999 .- 1526-7598. ; 114:4, s. 866-874
  • Tidskriftsartikel (refereegranskat)abstract
    • Dead space is the portion of a tidal volume that does not participate in gas exchange because it does not get in contact with blood flowing through the pulmonary capillaries. It is commonly calculated using volumetric capnography, the plot of expired carbon dioxide (CO2) versus tidal volume, which is an easy bedside assessment of the inefficiency of a particular ventilatory setting. Today, Bohr's original dead space can be calculated in an entirely noninvasive and breath-by-breath manner as the mean alveolar partial pressure of CO2 (PAco(2)) which can now be determined directly from the capnogram. The value derived from Enghoff's modification of Bohr's formula (using Paco(2) instead of PAco(2)) is a global index of the inefficiency of gas exchange rather than a true "dead space" because it is influenced by all causes of ventilation/perfusion mismatching, from real dead space to shunt. Therefore, the results obtained by Bohr's and Enghoff's formulas have different physiological meanings and clinicians must be conscious of such differences when interpreting patient data. In this article, we describe the rationale of dead space measurements by volumetric capnography and discuss its main clinical implications and the misconceptions surrounding it.
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48.
  • Tusman, Gerardo, et al. (författare)
  • Real-time images of tidal recruitment using lung ultrasound
  • 2015
  • Ingår i: Critical Ultrasound Journal. - : Springer Science and Business Media LLC. - 2036-3176 .- 2036-7902. ; 7
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Ventilator-induced lung injury is a form of mechanical damage leading to a pulmonary inflammatory response related to the use of mechanical ventilation enhanced by the presence of atelectasis. One proposed mechanism of this injury is the repetitive opening and closing of collapsed alveoli and small airways within these atelectatic areas-a phenomenon called tidal recruitment. The presence of tidal recruitment is difficult to detect, even with high-resolution images of the lungs like CT scan. The purpose of this article is to give evidence of tidal recruitment by lung ultrasound. Findings: A standard lung ultrasound inspection detected lung zones of atelectasis in mechanically ventilated patients. With a linear probe placed in the intercostal oblique position. We observed tidal recruitment within atelectasis as an improvement in aeration at the end of inspiration followed by the re-collapse at the end of expiration. This mechanism disappeared after the performance of a lung recruitment maneuver. Conclusions: Lung ultrasound was helpful in detecting the presence of atelectasis and tidal recruitment and in confirming their resolution after a lung recruitment maneuver.
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49.
  • Tusman, Gerardo, et al. (författare)
  • Reference values for volumetric capnography-derived non-invasive parameters in healthy individuals
  • 2013
  • Ingår i: Journal of clinical monitoring and computing. - : Springer Science and Business Media LLC. - 1387-1307 .- 1573-2614. ; 27:3, s. 281-288
  • Tidskriftsartikel (refereegranskat)abstract
    • The aim of this study was to determine typical values for non-invasive volumetric capnography (VCap) parameters for healthy volunteers and anesthetized individuals. VCap was obtained by a capnograph connected to the airway opening. We prospectively studied 33 healthy volunteers 32 +/- A 6 years of age weighing 70 +/- A 13 kg at a height of 171 +/- A 11 cm in the supine position. Data from these volunteers were compared with a cohort of similar healthy anesthetized patients ventilated with the following settings: tidal volume (VT) of 6-8 mL/kg, respiratory rate 10-15 bpm, PEEP of 5-6 cmH(2)O and FiO(2) of 0.5. Volunteers showed better clearance of CO2 compared to anesthetized patients as indicated by (median and interquartile range): (1) an increased elimination of CO2 per mL of VT of 0.028 (0.005) in volunteers versus 0.023 (0.003) in anesthetized patients, p < 0.05; (2) a lower normalized slope of phase III of 0.26 (0.17) in volunteers versus 0.39 (0.38) in anesthetized patients, p < 0.05; and (3) a lower Bohr dead space ratio of 0.23 (0.05) in volunteers versus 0.28 (0.05) in anesthetized patients, p < 0.05. This study presents reference values for non-invasive volumetric capnography-derived parameters in healthy individuals. Mechanical ventilation and anesthesia altered these values significantly.
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50.
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