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- Lo Mauro, Antonella, et al.
(författare)
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Adaptation of lung, chest wall, and respiratory muscles during pregnancy : preparing for birth
- 2019
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Ingår i: Journal of applied physiology. - : AMER PHYSIOLOGICAL SOC. - 8750-7587 .- 1522-1601. ; 127:6, s. 1640-1650
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Tidskriftsartikel (refereegranskat)abstract
- A plethora of physiological and biochemical changes occur during normal pregnancy. The changes in the respiratory system have not been as well elucidated, in part because radioimaging is usually avoided during pregnancy. We aimed to use several noninvasive methods to characterize the adaptation of the respiratory system during the full course of pregnancy in preparation for childbirth. Eighteen otherwise healthy women (32.3 +/- 2.8 yr) were recruited during early pregnancy. Spirometry, optoelectronic plethysmography, and ultrasonography were used to study changes in chest wall geometry, breathing pattern, lung and thoraco-abdominal volume variations, and diaphragmatic thickness in the first, second, and third trimesters. A group of nonpregnant women were used as control subjects. During the course of pregnancy, we observed a reorganization of rib cage geometry, in shape but not in volume. Despite the growing uterus, there was no lung restriction (forced vital capacity: 101 +/- 15% predicted), but we did observe reduced rib cage expansion. Breathing frequency and diaphragmatic contribution to tidal volume and inspiratory capacity increased. Diaphragm thickness was maintained (1st trimester: 2.7 +/- 0.8 mm, 3rd trimester: 2.5 +/- 0.9 mm; P = 0.187), possibly indicating a conditioning effect to compensate for the effects of the growing uterus. We conclude that pregnancy preserved lung volumes, abdominal muscles, and the diaphragm at the expense of rib cage muscles. NEW & NOTEWORTHY Noninvasive analysis of the kinematics of the chest wall and the diaphragm during resting conditions in pregnant women revealed significant changes in the pattern of thoracoabdominal breathing across the trimesters. That is, concomitant with the progressive changes of chest wall shape, the diaphragm increased its contribution to both spontaneous and maximal breathing, maintaining its thickness despite its lengthening due to the growing uterus. These results suggest that during pregnancy the diaphragm is conditioned to optimize its active role provided during parturition.
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- Lo Mauro, Antonella
(författare)
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Clinical and experimental studies on the diaphragm during physiological and pathophysio-logical conditions
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The diaphragm is the most important respiratory muscle. It separates the thorax from the abdomen and it is innervated by phrenic nerve. The action of the diaphragm strongly depends on the combination of: the conductivity of the phrenic nerve; b) the developed force (pressure); c) the length at which it contracts; d) the velocity of short- ening and e) the level of activation.The general aim of this doctoral thesis is to study the diaphragm in different conditions in which different mechanical loads and/or different agents modified one or more of these factors in order to understand how the diaphragm copes with anesthesia, phrenic nerve injury, severe lung diseases and increasing abdominal load.In Study I, the movement induced by the diaphragm on tumor marker surrogate, being a source of noise while planning target volume during stereotactic body radiation ther- apy was quantified. High Frequency Jet Ventilation at a frequency of 200 min-1 seemed to be the best compromise between immobilization and gas exchange.In Study II, the role of the diaphragm during the emergence from anesthesia (namely, propofol) was investigated, finding no contribution because of active contraction of the expiratory muscles in this phase, presumably triggered by the resistance in the tracheal tube.In Study III, an animal model (porcine) of phrenic nerve damage was created and the compensatory mechanisms of non-diaphragmatic respiratory muscles studied. A 12- fold augmentation of the drive to ribcage muscles occurred during inspiration, while it almost doubled for abdominal muscles during expiration. Increasing level of pres- sure support ventilation masked these respiratory muscles strategy.Study IV described, within an integrated multidisciplinary longitudinal study, differ- ent functional aspects (geometry, weakness, force, mobility, contractility, electrical activity and kinematics) of the diaphragm before and after lung transplantation. A subclinical diaphragmatic dysfunction occurs after surgery, despite appropriate clini- cal course and respiratory outcome, induced by phrenic nerve neurapraxia secondary to surgical procedure.Study V was a non-invasive and longitudinal study of the progressive changes of the diaphragm during healthy pregnancy. During pregnancy, the diaphragm is condi- tioned to optimize its active role provided during parturition, as its co-contraction with abdominal muscles plays a fundamental role in the phase of baby expulsion.
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- Lo Mauro, Antonella, et al.
(författare)
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Comparison of different methods for lung immobilization in an animal model
- 2020
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Ingår i: Radiotherapy and Oncology. - : Elsevier BV. - 0167-8140 .- 1879-0887. ; 150, s. 151-158
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND AND PURPOSE: Respiratory-induced motion introduces uncertainties in the delivery of dose in radiotherapy treatments. Various methods are used clinically, e.g. breath-holding, while there is limited experience with other methods such as apneic oxygenation and high frequency jet ventilation (HFJV). This study aims to compare the latter approaches for lung immobilization and their clinical impact on gas exchange in an animal model.MATERIALS AND METHODS: Two radiopaque tumor surrogate markers (TSM) were placed in the central (cTSM) and peripheral (dTSM) regions of the lungs in 9 anesthetized and muscle relaxed pigs undergoing 3 ventilatory interventions (1) HFJV at rates of 200 (JV200), 300 (JV300) and 400 (JV400) min-1; (2) apnea at continuous positive airway pressure (CPAP) levels of 0, 8 and 16 cmH2O; (3) conventional mechanical ventilation (CMV) as reference mode. cTSM and dTSM were visualized using fluoroscopy and their coordinates were computed. The ventilatory pattern was registered, and oxygen and carbon dioxide (pCO2) partial pressures were measured.RESULTS: The highest range of TSM motion, and ventilation was found during CMV, the lowest during apnea. During HFJV the amount of motion varied inversely with increasing frequency. The reduction of TSM motion at JV300, JV400 and all CPAP levels came at the cost of increased pCO2, however the relatively low frequency of 200 min-1 for HFJV was the only ventilatory setting that enabled adequate CO2 removal.CONCLUSION: In this model, HFJV at 200 min-1 was the best compromise between immobilization and gas exchange for sessions of 10-min duration.
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| 5. |
- Lo Mauro, Antonella, et al.
(författare)
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Physiological changes and compensatory mechanisms by the action of respiratory muscles in a porcine model of phrenic nerve injury
- 2021
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Ingår i: Journal of applied physiology. - : American Physiological Society. - 8750-7587 .- 1522-1601. ; 130:3, s. 813-826
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Tidskriftsartikel (refereegranskat)abstract
- Phrenic nerve damage may occur as a complication of specific surgical procedures, prolonged mechanical ventilation, or physical trauma. The consequent diaphragmatic paralysis or dysfunction can lead to major complications. The purpose of this study was to elucidate the role of the nondiaphragmatic respiratory muscles during partial or complete diaphragm paralysis induced by unilateral and bilateral phrenic nerve damage at different levels of ventilatory pressure support in an animal model. Ten pigs were instrumented, the phrenic nerve was exposed from the neck, and spontaneous respiration was preserved at three levels of pressure support, namely, high, low, and null, at baseline condition, after left phrenic nerve damage, and after bilateral phrenic nerve damage. Breathing pattern, thoracoabdominal volumes and asynchrony, and pressures were measured at each condition. Physiological breathing was predominantly diaphragmatic and homogeneously distributed between right and left sides. After unilateral damage, the paralyzed hemidiaphragm was passively dragged by the ipsilateral rib cage muscles and the contralateral hemidiaphragm. After bilateral damage, the drive to and the work of breathing of rib cage and abdominal muscles increased, to compensate for diaphragmatic paralysis, ensuing paradoxical thoracoabdominal breathing. Increasing level of pressure support ventilation replaces this muscle group compensation. When the diaphragm is paralyzed (unilaterally and/or bilaterally), there is a coordinated reorganization of nondiaphragmatic respiratory muscles as compensation that might be obscured by high level of pressure support ventilation. Noninvasive thoracoabdominal volume and asynchrony assessment could be useful in phrenic nerve-injured patients to estimate the extent and type of inspiratory muscle dysfunction.
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| 6. |
- LoMauro, Antonella, et al.
(författare)
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The diaphragm before and after lung transplant (LT)
- 2018
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Ingår i: European Respiratory Journal. - : EUROPEAN RESPIRATORY SOC JOURNALS LTD. - 0903-1936 .- 1399-3003. ; 52
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 7. |
- LoMauro, Antonella, et al.
(författare)
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The Effect Of Pregnancy On Respiratory Function
- 2018
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Ingår i: European Respiratory Journal. - : EUROPEAN RESPIRATORY SOC JOURNALS LTD. - 0903-1936 .- 1399-3003. ; 52
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 8. |
- LoMauro, Antonella, et al.
(författare)
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The impaired diaphragmatic function after bilateral lung transplantation : A multifactorial longitudinal study
- 2020
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Ingår i: The Journal of Heart and Lung Transplantation. - : ELSEVIER SCIENCE INC. - 1053-2498 .- 1557-3117. ; 39:8, s. 795-804
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Lung transplantation is a complex but effective treatment of end-stage pulmonary disease. Among the post-operative complications, phrenic nerve injury, and consequent diaphragmatic dysfunction are known to occur but are hitherto poorly described. We aimed to investigate the effect of lung transplantation on diaphragmatic function with a multimodal approach.METHODS: A total of 30 patients were studied at 4 time points: pre-operatively, at discharge after surgery, and after approximately 6 and subsequently 12 months post surgery. The diaphragmatic function was studied in terms of geometry (assessed by the radius of the diaphragmatic curvature delineated on chest X-ray), weakness (considering changes in forced vital capacity when the patient shifted from upright to supine position), force (maximal pressure during sniff), mobility (excursion of the dome of the diaphragm delineated by ultrasound), contractility (thickening fraction assessed by ultrasound), electrical activity (latency and area of compound muscle action potential during electrical stimulation of phrenic nerve), and kinematics (relative contribution of the abdominal compartment to tidal volume).RESULTS: Despite good clinical recovery (indicated by spirometry and 6 minutes walking test), a reduction of the diaphragmatic function was detected at discharge; it persisted 6 months later to recover fully 1 year after transplantation. Diaphragmatic dysfunction was demonstrated in terms of force, weakness, electrical activity, and kinematics. Our data suggest that the dysfunction was caused by phrenic nerve neurapraxia or moderate axonotmesis, potentially as a consequence of the surgical procedure (i.e., the use of ice and pericardium manipulation).CONCLUSIONS: The occurrence of diaphragmatic dysfunction in patients with a good clinical recovery indicates that the evaluation of diaphragmatic function should be included in the post-operative assessment after lung transplantation.
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| 10. |
- Sütterlin, Robert, et al.
(författare)
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Efficacy of Superimposed High Frequency Jet Ventilation and High Frequency Jet Ventilation in an Animal Model of Tracheal Obstruction
- 2014
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Ingår i: Anesthesiology. - 0003-3022 .- 1528-1175.
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- BackgroundSuperimposed high frequency jet ventilation (SHFJV) and high-frequency jet ventilation (HJFV) are widely used for airway interventions using rigid bronchoscopy. SHFJV was found to provide higher lung volume and better gas exchange than HFJV in unobstructed airways.We hypothesized that, also in the presence of airway obstruction, SHFJV would provide higher lung volumes, better oxygenation and more effective CO2 removal than HFJV.MethodsIn a porcine model, we used a stent with ID 4 mm to create tracheal obstruction. The anesthetized animals (25-31.5kg) were alternately ventilated with SHFJV (low frequency 16min-1, combined with a high frequency fHF) and HFJV (solely fHF) at a set of different fHF from 50-600min-1. Chest wall volume changes were measured with opto-electronic plethysmography, airway pressures were registered continuously and arterial blood gases were obtained repeatedly.ResultsSHFJV provided higher ∆EEVCW than HFJV with a difference between both modes of 129 ml (fHF=50min-1) to 62 ml (fHF=400min-1). Tidal volume (VT) was always greater than 213 ml with SHFJV, but with HFJV, increasing fHF reduced VT from 112 (97-130) ml at fHF=50 min-1 to negligible values at fHF>150 min-1.In analogy, SHFJV provided paO2 of >30 kPa and acceptable CO2 removal for all fHF, whereas fHF>150 min-1 resulted in severe hypoxia and hypercarbia during HFJV.ConclusionSHFJV effectively increased lung volumes and maintained gas exchange compared with HFJV. SHFJV may be a safer option than HFJV in laser surgery, where low FiO2 is required. HFJV with frequencies >100-150 min-1 should not be used in severe airway obstruction.
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