| 1. |
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| 2. |
- Brodtkorb, Thor-Henrik, et al.
(författare)
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Cost-effectiveness of clean air administered to the breathing zone in allergic asthma
- 2010
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Ingår i: CLINICAL RESPIRATORY JOURNAL. - 1752-6981. ; 4:2, s. 104-110
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: Airsonett Airshower (AA) is a novel non-pharmaceutical treatment for patients with perennial allergic asthma that uses a laminar airflow directed to the breathing zone of patients during sleep. It has been shown that AA treatment in addition to optimized standard therapy significantly increases asthma-related quality of life among adolescent asthmatics. However, the cost-effectiveness of AA treatment has not yet been assessed. As reimbursement decisions are increasingly guided by results from the cost-effectiveness analysis, such information is valuable for health-care policy-makers. Objective: The objective of this study was to estimate the cost-effectiveness of adding AA treatment with allergen-free air during night sleep to optimized standard therapy for adolescents with perennial allergic asthma compared with placebo. Materials and Methods: A probabilistic Markov model was developed to estimate costs and health outcomes over a 5-year period. Costs and effects are presented from a Swedish health-care perspective (QALYs). The main outcome of interest was cost per QALY gained. Results: The Airshower strategy resulted in a mean gain of 0.25 QALYs per patient, thus yielding a cost per QALY gained of under 35 000 as long as the cost of Airshower is below 8200. Conclusions: Adding AA treatment to optimized standard therapy for adolescents with perennial allergic asthma compared with placebo is generating additional QALYs at a reasonable cost. However, further studies taking more detailed resource use and events such as exacerbations into account would be needed to fully evaluate the cost-effectiveness of AA treatment. Please cite this paper as: Brodtkorb T-H, Zetterstrom O and Tinghog G. Cost-effectiveness of clean air administered to the breathing zone in allergic asthma.
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| 3. |
- Börjesson Axén, Jenny, 1986-, et al.
(författare)
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A dynamic gas pressure model for management of nickel metal hydride batteries
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The Nickel Metal Hydride (NiMH) battery has an active gas phase during operation. This is due in part to the aqueous electrolyte causing oxygen evolution on the positive nickel electrode, and in part due to the hydrogen stored in the negative metal hydride (MH) electrode being in equilibrium with gaseous hydrogen. The gas phase reactions are closely connected to the battery function and must therefore be accounted for when creating a successful battery management system (BMS).This study explores a pressure model for management of the NiMH battery. By using measured current, voltage, and temperature as input, the total pressure and gas composition can be modeled. Model parameters are fitted by comparing the modeled total pressure to the measured pressure. By using the system voltage signal, the difficulty of simultaneously modeling the voltage based on the current is circumvented. A model like this opens the way to new ways of battery system management through use of calculated partial pressures and deviations from the modeled total pressure. This can help increasing safety and longevity of battery systems.
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| 4. |
- Börjesson Axén, Jenny, 1986-, et al.
(författare)
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Creating a dynamic P2D model for the nickel metal hydride battery
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- In this study, a predictive voltage and pressure nickel metal hydride (NiMH) battery model is presented. The model was validated under conditions that would be seen in applications, with mixed charge and discharge usage patterns. The model is based on an extended P2D model using concentrated electrolyte and porous electrode theory. On top of the charging and discharging processes, the NiMH battery has additional side reactions that affects the battery behavior. These processes are important to include for a model to accurately reproduce the voltage and pressure behavior under usage like conditions. Two processes were identified as necessary for the model to be predictive: Open circuit voltage hysteresis and the gas phase reactions involving oxygen and hydrogen. To take these into account, results from two previous studies that modeled these phenomena separately was introduced into the model. Hysteresis was described using empirical mathematical expressions and the gas phase reactions were described using electrochemical rate equations.The results show that the resulting model is capable of qualitatively reproducing NiMH battery voltage and pressure behavior, both for a continuous charge/discharge cycle and a varied usage pattern with mixed charge and discharge pulses using different currents. The model was used to study the effect of changes in electrode thickness on the energy and power density during discharge. The mechanism behind the drop in cell voltage at the end of charge was also investigated and found to be connected to the temperature dependence of the oxygen evolution equilibrium potential. Although the model can be fine-tuned further to improve quantitative reproducibility, this study shows that taking the OCV hysteresis and gas phase reactions into account creates a basis for a NiMH battery model that can function for different usage patterns. Such a model has potential to improve the development and use of NiMH batteries, providing a tool to improve battery design and battery management algorithms.
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| 5. |
- Börjesson Axén, Jenny, 1986-
(författare)
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The dynamic behavior of the NiMH battery – Creating a versatile NiMH battery model
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- To facilitate the shift from fossil to renewable energy sources, energy storage is needed to cope with the intermittent nature of technologies such as solar, wind, and wave power. One storage alternative is battery-based stationary energy storage. There are many battery types to choose from, but Nickel Metal Hydride (NiMH) is a type that is especially well suited. These batteries have a high energy density, a large temperature operating window and are a safe alternative for large scale energy storage.In this thesis, the behavior of the NiMH battery is studied with the aim to develop a dynamic battery model, a model that is capable of reproducing the battery voltage and pressure, also for dynamic usage. Such a model can be used to facilitate development of NiMH batteries, improvement of the algorithms used in the Battery Management System (BMS), quality control, and dimensioning of energy storage systems. These improvements can lead to stationary energy storage with a higher efficiency and longer usable lifetime.To increase the understanding of the battery function, deeper study was carried out of two behaviors that are typical for the NiMH battery and are deemed to have a large impact on the battery: Open circuit voltage (OCV) hysteresis and the battery gas phase behavior. The OCV hysteresis complicates modelling because it causes the battery rest voltage at a certain degree of charge to depend on the charge/discharge path taken to get there. OCV hysteresis is not noticeable for all batteries, and it is especially prominent for the NiMH battery. The gas phase in the NiMH battery is active since the electrolyte is water based and the voltage window during operation causes oxygen evolution at the positive electrode. The oxygen is then recombined into water at the negative electrode. The amount of hydrogen in the gas phase varies over a cycle due to the the dependence on temperature and state of charge of the hydrogen equilibrium pressure over the negative metal hydride electrode.Two models were developed separately to study these behaviors. The models showed good qualitative reproduction capabilities. The hysteresis phenomenon was also studied using structural analysis methods. Differences were identified in the material structure between two samples of the positive electrode material at the same state of charge but different hysteresis states. These differences were found in both the bulk and the surface region of the particles. The differences in bulk were related to degree of disorder and the differences in the surface region to inhomogeneity in Li distribution in the cobalt oxyhydroxide layer. The gas composition was studied using mass spectrometry. The gas phase was mostly composed of nitrogen, but hydrogen was responsible for the majority of the pressure changes of the battery during a charge/discharge cycle. Oxygen could be detected at the end of charge, where it is produced due to high voltage on the positive electrode.Finally, the two models were added to a P2D-model. This model type is commonly used to simulate battery behavior, and is based on electrochemical theory with approximations used for the porous electrode behavior. The spacial distribution is modeled in one dimension with an additional dimension added locally to simulate intra particle diffusion. The combined model showed that the behavior seen from a NiMH during dynamic usage could be recreated qualitatively through adding OCV hysteresis and the gas phase behavior to this standard model type.
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| 6. |
- Drevhammar, Thomas, et al.
(författare)
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Comparison of Nasal Continuous Positive Airway Pressure Delivered by Seven Ventilators Using Simulated Neonatal Breathing
- 2013
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Ingår i: Pediatric Critical Care Medicine. - 1529-7535 .- 1947-3893. ; 14:4, s. E196-E201
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: Nasal continuous positive airway pressure (NCPAP) is an established treatment for respiratory distress in neonates. Most modern ventilators are able to provide NCPAP. There have been no large studies examining the properties of NCPAP delivered by ventilators. The aim of this study was to compare pressure stability and imposed work of breathing (iWOB) for NCPAP delivered by ventilators using simulated neonatal breathing. Design: Experimental in vitro study. Setting: Research laboratory in Sweden. Intervention: None. Measurements and Main Results: Neonatal breathing was simulated using a mechanical lung simulator. Seven ventilators were tested at different CPAP levels using two breath profiles. Pressure stability and iWOB were determined. Results from three ventilators revealed that they provided a slight pressure support. For these ventilators, iWOB could not be calculated. There were large differences in pressure stability and iWOB between the tested ventilators. For simulations using the 3.4-kg breath profile, the pressure swings around the mean pressure were more than five times greater, and iWOB more than four times higher, for the system with the highest measured values compared with the system with the lowest. Overall, the Fabian ventilator was the most pressure stable system. Evita XL and SERVO-i were found more pressure stable than Fabian in some simulations. The results for iWOB were in accordance with pressure stability for systems that allowed determination of this variable. Conclusions: Some of the tested ventilators unexpectedly provided a minor degree of pressure support. In terms of pressure stability, we have not found any advantages of ventilators as a group compared with Bubble CPAP, Neopuff, and variable flow generators that were tested in our previous study. The variation between individual systems is great within both categories. The clinical importance of these findings needs further investigation.
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| 7. |
- Drevhammar, Thomas, et al.
(författare)
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Comparison of seven infant continuous positive airway pressure systems using simulated neonatal breathing
- 2012
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Ingår i: Pediatric Critical Care Medicine. - 1529-7535 .- 1947-3893. ; 13:2, s. E113-E119
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Continuous positive airway pressure is an established treatment for respiratory distress in neonates. Continuous positive airway pressure has been applied to infants using an array of devices. The aim of this experimental study was to investigate the characteristics of seven continuous positive airway pressure systems using simulated breath profiles from newborns. Design: Experimental in vitro study. Setting: Research laboratory in Sweden. Intervention: None. Measurements and Main Results: In vitro simulation of spontaneous neonatal breathing was achieved with a mechanical lung model. Simulation included two breath profiles, three levels of continuous positive airway pressure with and without short binasal prongs and different levels of constant leak. Pressure stability and imposed work of breathing were determined. Seven continuous positive airway pressure systems were tested. There were large differences in pressure stability and imposed work of breathing between tested continuous positive airway pressure systems. Neopuff and Medijet had the highest pressure instability and imposed work of breathing. Benveniste, Hamilton Universal (Arabella), and Bubble continuous positive airway pressure showed intermediate results. AirLife and Infant Flow had the lowest pressure instability and imposed work of breathing. AirLife and Infant Flow showed the least decrease in delivered pressure when challenged with constant leak. Conclusion: The seven tested continuous positive airway pressure systems showed large variations in pressure stability and imposed work of breathing. They also showed large differences in how well they maintain continuous positive airway pressure when exposed to leak. For most systems, imposed work of breathing increased with increasing continuous positive airway pressure level. The clinical importance of the difference in pressure stability is uncertain. Our results may facilitate the design of clinical studies examining the effect of pressure stability on outcome.
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| 8. |
- Edmark, Lennart, et al.
(författare)
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Preserved oxygenation in obese patients receiving protective ventilation during laparoscopic surgery : a randomized controlled study
- 2016
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Ingår i: Acta Anaesthesiologica Scandinavica. - : Wiley. - 0001-5172 .- 1399-6576. ; 60:1, s. 26-35
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Venous admixture from atelectasis and airway closure impedes oxygenation during general anaesthesia. We tested the hypothesis that continuous positive airway pressure (CPAP) during pre-oxygenation and reduced fraction of inspiratory oxygen (FIO2 ) during emergence from anaesthesia can improve oxygenation in patients with obesity undergoing laparoscopic surgery.METHODS: In the intervention group (n = 20, median BMI 41.9), a CPAP of 10 cmH2 O was used during pre-oxygenation and induction of anaesthesia, but no CPAP was used in the control group (n = 20, median BMI 38.1). During anaesthesia, all patients were ventilated in volume-controlled mode with an FIO2 of 0.4 and a positive end-expiratory pressure (PEEP) of 10 cmH2 O. During emergence, before extubation, the control group was given an FIO2 of 1.0 and the intervention group was divided into two subgroups, which were given an FIO2 of 1.0 or 0.31. Oxygenation was assessed perioperatively by the estimated venous admixture (EVA).RESULTS: The median EVA before pre-oxygenation was about 8% in both groups. During anaesthesia after intubation, the median EVA was 8.2% in the intervention vs. 13.2% in the control group (P = 0.048). After CO2 pneumoperitoneum, the median EVA was 8.4% in the intervention vs. 9.9% in the control group (P > 0.05). One hour post-operatively, oxygenation had deteriorated in patients given an FIO2 of 1.0 during emergence but not in patients given an FIO2 of 0.31.CONCLUSIONS: A CPAP of 10 cmH2 O during pre-oxygenation and induction, followed by PEEP after intubation, seemed to preserve oxygenation during anaesthesia. Post-operative oxygenation depended on the FIO2 used during emergence.
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| 9. |
- Johansson, Joakim, et al.
(författare)
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Prehospital analgesia using nasal administration of S-ketamine : a case series
- 2013
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Ingår i: Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine. - : BioMed Central. - 1757-7241. ; 21
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Tidskriftsartikel (refereegranskat)abstract
- Pain is a problem that often has to be addressed in the prehospital setting. The delivery of analgesia may sometimes prove challenging due to problems establishing intravenous access or a harsh winter environment. To solve the problem of intravenous access, intranasal administration of drugs is used in some settings. In cases where vascular access was foreseen or proved hard to establish (one or two missed attempts) on the scene of the accident we use nasally administered S-Ketamine for prehospital analgesia. Here we describe the use of nasally administered S-Ketamine in 9 cases. The doses used were in the range of 0,45-1,25 mg/kg. 8 patients were treated in outdoor winter-conditions in Sweden. 1 patient was treated indoor. VAS-score decreased from a median of 10 (interquartile range 8-10) to 3 (interquartile range 2-4). Nasally administered S-Ketamine offers a possible last resource to be used in cases where establishing vascular access is difficult or impossible. Side-effects in these 9 cases were few and non serious. Nasally administered drugs offer a needleless approach that is advantageous for the patient as well as for health personnel in especially challenging selected cases. Nasal as opposed to intravenous analgesia may reduce the time spent on the scene of the accident and most likely reduces the need to expose the patient to the environment in especially challenging cases of prehospital analgesia. Nasal administration of S-ketamine is off label and as such we only use it as a last resource and propose that the effect and safety of the treatment should be further studied.
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| 19. |
- Nordin, Pär, et al.
(författare)
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Local, regional, or general anaesthesia in groin hernia repair : multicentre randomised trial
- 2003
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Ingår i: The Lancet. - 0140-6736 .- 1474-547X. ; 362:9387, s. 853-858
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundIn specialised centres, local anaesthesia is almost always used in groin hernia surgery; whereas in routine surgical practice, regional or general anaesthesia are the methods of choice. In this three-arm multicentre randomised trial, we aimed to compare the three methods of anaesthesia and to determine the extent to which general surgeons can reproduce the excellent results obtained with local anaesthesia in specialised hernia centres.MethodsBetween January, 1999, and December, 2001, 616 patients at ten hospitals, were randomly assigned to have either local, regional, or general anaesthesia. Primary endpoints were early and late postoperative complications. Secondary endpoints were duration of surgery and anaesthesia, length of postoperative hospital stay, and time to normal activity. Analysis was by intention to treat.FindingsIntraoperative tolerance for local anaesthesia was high. In the early postoperative period, local anaesthesia was superior to the other two types with respect to almost all endpoints. At 8 days' and 30 days' follow-up, there were no significant differences between the three groups. Although the mean duration of surgery was longer, the total anaesthesia time—ie, time from the start of anaesthesia until the patient left the operating room—was significantly shorter than it was for regional or general anaesthesia.InterpretationLocal anaesthesia has substantial advantages compared with regional or general anaesthesia, such as shorter duration of admission, less postoperative pain, and fewer micturition difficulties. The favourable results obtained with local anaesthesia in specialised hernia centres can, to a great extent, be reproduced by general surgeons in routine surgical practice.
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| 20. |
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| 21. |
- Schollin Borg, M, et al.
(författare)
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Blood lactate is a useful indicator for the Medical Emergency Team
- 2016
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Ingår i: Critical Care Research and Practice. - : Hindawi Limited. - 2090-1305 .- 2090-1313.
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Tidskriftsartikel (refereegranskat)abstract
- Lactate has been thoroughly studied and found useful for stratification of patients with sepsis, in the Intensive Care Unit, and trauma care. However, little is known about lactate as a risk-stratification marker in the Medical Emergency Team- (MET-) call setting. We aimed to determine whether the arterial blood lactate level at the time of a MET-call is associated with increased 30-day mortality. This is an observational study on a prospectively gathered cohort at a regional secondary referral hospital. All MET-calls during the two-year study period were eligible. Beside blood lactate, age and vital signs were registered at the call. Among the 211 calls included, there were 64 deaths (30.3%). Median lactate concentration at the time of the MET-call was 1.82 mmol/L (IQR 1.16–2.7). We found differences between survivors and nonsurvivors for lactate and oxygen saturation, a trend for age, but no significant correlations between mortality and systolic blood pressure, respiratory rate, and heart rate. As compared to normal lactate (<2.44 mmol/L), OR for 30-day mortality was 3.54 (p < 0.0006) for lactate 2.44–5.0 mmol/L and 4.45 (p < 0.0016) for lactate > 5.0 mmol/L. The present results support that immediate measurement of blood lactate in MET call patients is a useful tool in the judgment of illness severity.
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| 22. |
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| 23. |
- Stranneheim, Henrik, et al.
(författare)
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Rapid pulsed whole genome sequencing for comprehensive acute diagnostics of inborn errors of metabolism
- 2014
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Ingår i: BMC Genomics. - : Springer Science and Business Media LLC. - 1471-2164. ; 15, s. 1090-
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Tidskriftsartikel (refereegranskat)abstract
- Background: Massively parallel DNA sequencing (MPS) has the potential to revolutionize diagnostics, in particular for monogenic disorders. Inborn errors of metabolism (IEM) constitute a large group of monogenic disorders with highly variable clinical presentation, often with acute, nonspecific initial symptoms. In many cases irreversible damage can be reduced by initiation of specific treatment, provided that a correct molecular diagnosis can be rapidly obtained. MPS thus has the potential to significantly improve both diagnostics and outcome for affected patients in this highly specialized area of medicine. Results: We have developed a conceptually novel approach for acute MPS, by analysing pulsed whole genome sequence data in real time, using automated analysis combined with data reduction and parallelization. We applied this novel methodology to an in-house developed customized work flow enabling clinical-grade analysis of all IEM with a known genetic basis, represented by a database containing 474 disease genes which is continuously updated. As proof-of-concept, two patients were retrospectively analysed in whom diagnostics had previously been performed by conventional methods. The correct disease-causing mutations were identified and presented to the clinical team after 15 and 18 hours from start of sequencing, respectively. With this information available, correct treatment would have been possible significantly sooner, likely improving outcome. Conclusions: We have adapted MPS to fit into the dynamic, multidisciplinary work-flow of acute metabolic medicine. As the extent of irreversible damage in patients with IEM often correlates with timing and accuracy of management in early, critical disease stages, our novel methodology is predicted to improve patient outcome. All procedures have been designed such that they can be implemented in any technical setting and to any genetic disease area. The strategy conforms to international guidelines for clinical MPS, as only validated disease genes are investigated and as clinical specialists take responsibility for translation of results. As follow-up in patients without any known IEM, filters can be lifted and the full genome investigated, after genetic counselling and informed consent.
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| 24. |
- Sörensen, Lene, et al.
(författare)
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Expanded Screening of One Million Swedish Babies with R4S and CLIR for Post-Analytical Evaluation of Data.
- 2020
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Ingår i: International journal of neonatal screening. - : MDPI AG. - 2409-515X. ; 6:2
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Tidskriftsartikel (refereegranskat)abstract
- Sweden has one neonatal screening laboratory, receiving 115 to 120 thousand samples per year. Among the one million babies screened by tandem mass spectrometry from November 2010 until July 2019, a total of 665 babies were recalled and 311 verified as having one of the diseases screened for with this methodology, giving a positive predictive value (PPV) of 47% and an incidence of 1:3200. The PPV was high (41%) already in the first year after start of screening, thanks to the availability of the collaborative project Region 4 Stork database. The PPV is presently 58%. This improvement was achieved by the implementation of second-tier analyses in the screening for methylmalonic aciduria, propionic aciduria, isovaleric aciduria, and homocystinuria, and the employment of various post analytical tools of the Region 4 Stork, and its successor the collaborative laboratory integrated reports.
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| 25. |
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| 26. |
- Yucel, Yasemin Duygu, et al.
(författare)
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Enhancing Structural Battery Performance : Investigating the Role of Conductive Carbon Additives in LiFePO4-Impregnated Carbon Fiber Electrodes
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- This study centers on investigating the influence of conductive additives, carbon black (Super P) and graphene, within the context of LiFePO4 (LFP)-impregnated carbon fibers (CFs) produced using the powder impregnation method. The performance of these additives was subject to an electrochemical evaluation. The findings reveal that there are no substantial disparities between the two additives at lower cycling rates, highlighting their adaptability in conventional energy storage scenarios. However, as cycling rates increase, graphene emerges as the better performer. At a rate of 1.5C in a half-cell versus lithium, electrodes containing graphene exhibited a discharge capacity of 83 mAh g-1LFP ; those with Super P and without any additional conductive additive showed a capacity of 65 mAh g-1LFP and 48 mAh g-1LFP , respectively. This distinction is attributed to the structural and conductivity advantages inherent to graphene, showing its potential to enhance the electrochemical performance of structural batteries. Furthermore, LFP-impregnated CFs were evaluated in full cells versus pristine CFs, yielding relatively similar results, though with a slightly improved outcome observed with the graphene additive. These results provide valuable insights into the role of conductive additives in structural batteries and their responsiveness to varying operational conditions, underlining the potential for versatile energy storage solutions.
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| 27. |
- Yucel, Yasemin Duygu, et al.
(författare)
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Enhancing structural battery performance: Investigating the role of conductive carbon additives in LiFePO4-Impregnated carbon fiber electrodes
- 2024
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Ingår i: Composites Science And Technology. - : Elsevier BV. - 0266-3538 .- 1879-1050. ; 251
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Tidskriftsartikel (refereegranskat)abstract
- This study centers on investigating the influence of conductive additives, carbon black (Super P) and graphene, within the context of LiFePO4 (LFP)-impregnated carbon fibers (CFs) produced using the powder impregnation method. The performance of these additives was subject to an electrochemical evaluation. The findings reveal that there are no substantial disparities between the two additives at lower cycling rates, highlighting their adaptability in conventional energy storage scenarios. However, as cycling rates increase, graphene emerges as the better performer. At a rate of 1.5C in a half-cell versus lithium, electrodes containing graphene exhibited a discharge capacity of 83 mAhgLFP−1; those with Super P and without any additional conductive additive showed a capacity of 65 mAhgLFP−1 and 48 mAhgLFP−1, respectively. This distinction is attributed to the structural and conductivity advantages inherent to graphene, showing its potential to enhance the electrochemical performance of structural batteries. Furthermore, LFP-impregnated CFs were evaluated in full cells versus pristine CFs, yielding relatively similar results, though with a slightly improved outcome observed with the graphene additive. These results provide valuable insights into the role of conductive additives in structural batteries and their responsiveness to varying operational conditions, underlining the potential for versatile energy storage solutions.
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| 34. |
- Zetterström, Henrik
(författare)
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Att välja anestesiform
- 2016. - 3
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Ingår i: Anestesi. - : Liber. - 9789147100545 ; , s. 249-258
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 35. |
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| 36. |
- Zetterström, Henrik
(författare)
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Dokumentation
- 2005. - 2
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Ingår i: Anestesi. - : Liber. ; , s. 330-340
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 44. |
- Östberg, Erland, et al.
(författare)
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Minimizing atelectasis formation during general anaesthesia-oxygen washout is a non-essential supplement to PEEP
- 2017
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Ingår i: Upsala Journal of Medical Sciences. - : TAYLOR & FRANCIS LTD. - 0300-9734 .- 2000-1967. ; 122:2, s. 92-98
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Tidskriftsartikel (refereegranskat)abstract
- Background: Following preoxygenation and induction of anaesthesia, most patients develop atelectasis. We hypothesized that an immediate restoration to a low oxygen level in the alveoli would prevent atelectasis formation and improve oxygenation during the ensuing anaesthesia. Methods: We randomly assigned 24 patients to either a control group (n=12) or an intervention group (n=12) receiving an oxygen washout procedure directly after intubation. Both groups were, depending on body mass index, ventilated with a positive end-expiratory pressure (PEEP) of 6-8 cmH(2)O during surgery. The atelectasis area was studied by computed tomography before emergence. Oxygenation levels were evaluated by measuring blood gases and calculating estimated venous admixture (EVA). Results: The atelectasis areas expressed as percentages of the total lung area were 2.0 (1.5-2.7) (median [interquartile range]) and 1.8 (1.4-3.3) in the intervention and control groups, respectively. The difference was non-significant, and also oxygenation was similar between the two groups. Compared to oxygenation before the start of anaesthesia, oxygenation at the end of surgery was improved in the intervention group, mean (SD) EVA from 7.6% (6.6%) to 3.9% (2.9%) (P=.019) and preserved in the control group, mean (SD) EVA from 5.0% (5.3%) to 5.6% (7.1%) (P=.59). .Conclusion: Although the oxygen washout restored a low pulmonary oxygen level within minutes, it did not further reduce atelectasis size. Both study groups had small atelectasis and good oxygenation. These results suggest that a moderate PEEP alone is sufficient to minimize atelectasis and maintain oxygenation in healthy patients.
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| 45. |
- Östberg, Erland, et al.
(författare)
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Positive End-expiratory Pressure Alone Minimizes Atelectasis Formation in Nonabdominal Surgery : A Randomized Controlled Trial
- 2018
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Ingår i: Anesthesiology. - : LIPPINCOTT WILLIAMS & WILKINS. - 0003-3022 .- 1528-1175. ; 128:6, s. 1117-1124
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Tidskriftsartikel (refereegranskat)abstract
- Background: Various methods for protective ventilation are increasingly being recommended for patients undergoing general anesthesia. However, the importance of each individual component is still unclear. In particular, the perioperative use of positive end-expiratory pressure (PEEP) remains controversial. The authors tested the hypothesis that PEEP alone would be sufficient to limit atelectasis formation during nonabdominal surgery. Methods: This was a randomized controlled evaluator-blinded study. Twenty-four healthy patients undergoing general anesthesia were randomized to receive either mechanical ventilation with PEEP 7 or 9 cm H2O depending on body mass index (n = 12) or zero PEEP (n =12). No recruitment maneuvers were used. Hie primary outcome was atelectasis area as studied by computed tomography in a transverse scan near the diaphragm, at the end of surgery, before emergence. Oxygenation was evaluated by measuring blood gases and calculating the ratio of arterial oxygen partial pressure to inspired oxygen fraction (Pao(2)/Fio(2) ratio). Results: At the end of surgery, the median (range) atelectasis area, expressed as percentage of the total lung area, was 1.8 (0.3 to 9.9) in the PEEP group and 4.6 (1.0 to 10.2) in the zero PEEP group. Tire difference in medians was 2.8% (95% CI, 1.7 to 5.7%; A = 0.002). Oxygenation and carbon dioxide elimination were maintained in the PEEP group, but both deteriorated in the zero PEEP group. Conclusions: During nonabdominal surgery, adequate PEEP is sufficient to minimize atelectasis in healthy lungs and thereby maintain oxygenation. Titus, routine recruitment maneuvers seem unnecessary, and the authors suggest that they should only be utilized when clearly indicated.
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| 46. |
- Östberg, Erland, 1971-, et al.
(författare)
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Positive End-expiratory Pressure and Postoperative Atelectasis : A Randomized Controlled Trial
- 2019
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Ingår i: Anesthesiology. - 0003-3022 .- 1528-1175. ; 131:4, s. 809-817
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Tidskriftsartikel (refereegranskat)abstract
- Background: Positive end-expiratory pressure (PEEP) increases lung volume and protects against alveolar collapse during anesthesia. During emergence, safety preoxygenation preparatory to extubation makes the lung susceptible to gas absorption and alveolar collapse, especially in dependent regions being kept open by PEEP. We hypothesized that withdrawing PEEP before starting emergence preoxygenation would limit postoperative atelectasis formation.Methods: This was a randomized controlled evaluator-blinded trial in 30 healthy patients undergoing nonabdominal surgery under general anesthesia and mechanical ventilation with PEEP 7 or 9 cm H2O depending on body mass index. A computed tomography scan at the end of surgery assessed baseline atelectasis. The study subjects were thereafter allocated to either maintained PEEP (n = 16) or zero PEEP (n = 14) during emergence preoxygenation. The primary outcome was change in atelectasis area as evaluated by a second computed tomography scan 30 min after extubation. Oxygenation was assessed by arterial blood gases.Results: Baseline atelectasis was small and increased modestly during awakening, with no statistically significant difference between groups. With PEEP applied during awakening, the increase in atelectasis area was median ( range) 1.6 (-1.1 to 12.3) cm(2) and without PEEP 2.3 (-1.6 to 7.8) cm(2). The difference was 0.7 cm(2) (95% CI, -0.8 to 2.9 cm(2); P = 0.400). Postoperative atelectasis for all patients was median 5.2 cm(2) (95% CI, 4.3 to 5.7 cm(2)), corresponding to median 2.5% of the total lung area (95% CI, 2.0 to 3.0%). Postoperative oxygenation was unchanged in both groups when compared to oxygenation in the preoperative awake state.Conclusions: Withdrawing PEEP before emergence preoxygenation does not reduce atelectasis formation after nonabdominal surgery. Despite using 100% oxygen during awakening, postoperative atelectasis is small and does not affect oxygenation, possibly conditional on an open lung during anesthesia, as achieved by intraoperative PEEP.
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