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  • 1.
    Broche, L.
    et al.
    ESRF, Grenoble, France.;Univ Bari, Bari, Italy..
    Tannoia, A.
    Pellegrini, Mariangela
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory.
    Derosa, S.
    Sindaco, A.
    Borges, João Batista
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Clinical Physiology.
    Porra, L.
    Univ Helsinki, Helsinki, Finland..
    Larsson, Anders
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Hedenstierna, Göran
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Clinical Physiology.
    Bravin, A.
    ESRF, Grenoble, France..
    Perchiazzi, G.
    Wexler, A. S.
    Univ Calif Davis, Davis, CA 95616 USA..
    Verbanck, S.
    UZ Brussel, Brussels, Belgium..
    Bates, J. H. T.
    Univ Vermont, Burlington, VT USA..
    Bayat, S.
    Univ Picardie Med Sch CHU Amiens, Amiens, France..
    Role Of Parenchymal Interdependence In The Short-Term Dynamics Of Recruitment/derecruitment In Injured Lung: A Modelling Study2015In: American Journal of Respiratory and Critical Care Medicine, ISSN 1073-449X, E-ISSN 1535-4970, Vol. 191Article in journal (Other academic)
  • 2.
    Broche, Ludovic
    et al.
    European Synchrotron Radiat Facil, Biomed Beamline ID17, Grenoble, France.;Univ Picardie Jules Verne, INSERM, Dept Pediat Pulmonol, U1105, Amiens, France.;Amiens Univ Hosp, Amiens, France..
    Perchiazzi, Gaetano
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Porra, Liisa
    Univ Helsinki, Dept Phys, Helsinki, Finland.;Univ Helsinki, Cent Hosp, Helsinki, Finland..
    Tannoia, Angela
    Univ Bari, Dept Emergency & Organ Transplant, Bari, Italy..
    Pellegrini, Mariangela
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Derosa, Savino
    Univ Bari, Dept Emergency & Organ Transplant, Bari, Italy..
    Sindaco, Alessandra
    Univ Bari, Dept Emergency & Organ Transplant, Bari, Italy..
    Borges, João Batista
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory.
    Degrugilliers, Loic
    Univ Picardie Jules Verne, INSERM, Dept Pediat Pulmonol, U1105, Amiens, France.;Amiens Univ Hosp, Amiens, France..
    Larsson, Anders
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory.
    Hedenstierna, Göran
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Clinical Physiology. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory.
    Wexler, Anthony S.
    Univ Calif Davis, Dept Mech Engn, Davis, CA 95616 USA.;Univ Calif Davis, Environm Qual Lab, Davis, CA 95616 USA..
    Bravin, Alberto
    European Synchrotron Radiat Facil, Biomed Beamline ID17, Grenoble, France..
    Verbanck, Sylvia
    Univ Hosp UZ Brussel, Div Resp, Brussels, Belgium..
    Smith, Bradford J.
    Univ Vermont, Dept Med, Burlington, VT USA. European Synchrotron Radiat Facil, Grenoble, France..
    Bates, Jason H. T.
    Univ Vermont, Dept Med, Burlington, VT USA. European Synchrotron Radiat Facil, Grenoble, France..
    Bayat, Sam
    Univ Picardie Jules Verne, INSERM, Dept Pediat Pulmonol, U1105, Amiens, France.;Amiens Univ Hosp, Amiens, France..
    Dynamic Mechanical Interactions Between Neighboring Airspaces Determine Cyclic Opening and Closure in Injured Lung2017In: Critical Care Medicine, ISSN 0090-3493, E-ISSN 1530-0293, Vol. 45, no 4, p. 687-694Article in journal (Refereed)
    Abstract [en]

    Objectives: Positive pressure ventilation exposes the lung to mechanical stresses that can exacerbate injury. The exact mechanism of this pathologic process remains elusive. The goal of this study was to describe recruitment/derecruitment at acinar length scales over short-time frames and test the hypothesis that mechanical interdependence between neighboring lung units determines the spatial and temporal distributions of recruitment/derecruitment, using a computational model. Design: Experimental animal study. Setting: International synchrotron radiation laboratory. Subjects: Four anesthetized rabbits, ventilated in pressure controlled mode. Interventions: The lung was consecutively imaged at - 1.5-minute intervals using phase-contrast synchrotron imaging, at positive end expiratory pressures of 12, 9, 6, 3, and 0 cm H2O before and after lavage and mechanical ventilation induced injury. The extent and spatial distribution of recruitment/derecruitment was analyzed by subtracting subsequent images. In a realistic lung structure, we implemented a mechanistic model in which each unit has individual pressures and speeds of opening and closing. Derecruited and recruited lung fractions (F-derecruaed, F-recruited) were computed based on the comparison of the aerated volumes at successive time points. Measurements and Main Results: Alternative recruitment/derecruitment occurred in neighboring alveoli over short-time scales in all tested positive end-expiratory pressure levels and despite stable pressure controlled mode. The computational model reproduced this behavior only when parenchymal interdependence between neighboring acini was accounted for. Simulations closely mimicked the experimental magnitude of F-derecruited and F-recruited when mechanical interdependence was included, while its exclusion gave F-recruited values of zero at positive end -expiratory pressure greater than or equal to 3 cm H2O. Conclusions: These findings give further insight into the microscopic behavior of the injured lung and provide a means of testing protective-ventilation strategies to prevent recruitment/derecruitment and subsequent lung damage.

  • 3.
    Broche, Ludovic
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory. European Synchrotron Radiat Facil, Biomed Beamline ID17, Grenoble, France.
    Pisa, Pauline
    Univ Picardie Jules Verne, Fac Med, Amiens, France.
    Porra, Liisa
    Univ Helsinki, Dept Phys, Helsinki, Finland;Univ Helsinki, Cent Hosp, Med Imaging Ctr, Helsinki, Finland.
    Degrugilliers, Loic
    Amiens Univ Hosp, Dept Pediat Intens Care, Amiens, France.
    Bravin, Alberto
    European Synchrotron Radiat Facil, Biomed Beamline ID17, Grenoble, France.
    Pellegrini, Mariangela
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory.
    Batista Borges, João
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory.
    Perchiazzi, Gaetano
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory.
    Larsson, Anders
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory.
    Hedenstierna, Göran
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory.
    Bayat, Sam
    Univ Grenoble Alpes, Grenoble, France;INSERM, UA7, STROBE Lab, Grenoble, France;Grenoble Univ Hosp, Dept Pulmonol & Physiol, Grenoble, France.
    Individual Airway Closure Characterized In Vivo by Phase-Contrast CT Imaging in Injured Rabbit Lung2019In: Critical Care Medicine, ISSN 0090-3493, E-ISSN 1530-0293, Vol. 47, no 9, p. E774-E781Article in journal (Refereed)
    Abstract [en]

    Objectives: Airway closure is involved in adverse effects of mechanical ventilation under both general anesthesia and in acute respiratory distress syndrome patients. However, direct evidence and characterization of individual airway closure is lacking. Here, we studied the same individual peripheral airways in intact lungs of anesthetized and mechanically ventilated rabbits, at baseline and following lung injury, using high-resolution synchrotron phase-contrast CT.

    Design: Laboratory animal investigation.

    Setting: European synchrotron radiation facility.

    Subjects: Six New-Zealand White rabbits.

    Interventions: The animals were anesthetized, paralyzed, and mechanically ventilated in pressure-controlled mode (tidal volume, 6 mL/kg; respiratory rate, 40; Fio(2), 0.6; inspiratory:expiratory, 1:2; and positive end-expiratory pressure, 3 cm H2O) at baseline. Imaging was performed with a 47.5 x 47.5 x 47.5 mu m voxel size, at positive end-expiratory pressure 12, 9, 6, 3, and 0 cm H2O. The imaging sequence was repeated after lung injury induced by whole-lung lavage and injurious ventilation in four rabbits. Cross-sections of the same individual airways were measured.

    Measurements and Main Results: The airways were measured at baseline (n = 48; radius, 1.7 to 0.21 mm) and after injury (n = 32). Closure was observed at 0 cm H2O in three of 48 airways (6.3%; radius, 0.350.08 mm at positive end-expiratory pressure 12) at baseline and five of 32 (15.6%; radius, 0.28 +/- 0.09 mm) airways after injury. Cross-section was significantly reduced at 3 and 0 cm H2O, after injury, with a significant relation between the relative change in cross-section and airway radius at 12 cm H2O in injured, but not in normal lung (R = 0.60; p < 0.001).

    Conclusions: Airway collapsibility increases in the injured lung with a significant dependence on airway caliber. We identify "compliant collapse" as the main mechanism of airway closure in initially patent airways, which can occur at more than one site in individual airways.

  • 4.
    Gudmundsson, M
    et al.
    Department of Anaesthesiology and Intensive Care Medicine, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
    Perchiazzi, G
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Clinical Physiology. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Pellegrini, Mariangela
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Vena, A
    Department of Emergency and Organ Transplant, Bari University, Bari, Italy.
    Hedenstierna, Göran
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Clinical Physiology. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory.
    Rylander, Christian
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences. Department of Anaesthesiology and Intensive Care Medicine, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
    Atelectasis is inversely proportional to transpulmonary pressure during weaning from ventilator support in a large animal model2018In: Acta Anaesthesiologica Scandinavica, ISSN 0001-5172, E-ISSN 1399-6576, Vol. 62, no 1, p. 94-104Article in journal (Refereed)
    Abstract [en]

    Background

    In mechanically ventilated, lung injured, patients without spontaneous breathing effort, atelectasis with shunt and desaturation may appear suddenly when ventilator pressures are decreased. It is not known how such a formation of atelectasis is related to transpulmonary pressure (PL) during weaning from mechanical ventilation when the spontaneous breathing effort is increased. If the relation between PL and atelectasis were known, monitoring of PL might help to avoid formation of atelectasis and cyclic collapse during weaning. The main purpose of this study was to determine the relation between PL and atelectasis in an experimental model representing weaning from mechanical ventilation.

    Methods

    Dynamic transverse computed tomography scans were acquired in ten anaesthetized, surfactant-depleted pigs with preserved spontaneous breathing, as ventilator support was lowered by sequentially reducing inspiratory pressure and positive end expiratory pressure in steps. The volumes of gas and atelectasis in the lungs were correlated with PL obtained using oesophageal pressure recordings. Work of breathing (WOB) was assessed from Campbell diagrams.

    Results

    Gradual decrease in PL in both end-expiration and end-inspiration caused a proportional increase in atelectasis and decrease in the gas content (linear mixed model with an autoregressive correlation matrix; P < 0.001) as the WOB increased. However, cyclic alveolar collapse during tidal ventilation did not increase significantly.

    Conclusion

    We found a proportional correlation between atelectasis and PL during the ‘weaning process’ in experimental mild lung injury. If confirmed in the clinical setting, a gradual tapering of ventilator support can be recommended for weaning without risk of sudden formation of atelectasis.

  • 5.
    Pellegrini, Mariangela
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Regional Lung Mechanics and Influence of an Active Diaphragm in Experimental Lung Injury2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Despite being an essential life-support strategy in severe respiratory failure, mechanical ventilation can, if not optimally set and monitored, lead to injury of the lung parenchyma and diaphragm. These conditions are called ventilator-induced lung injury and ventilator-induced diaphragmatic dysfunction (VIDD), respectively. Although substantial progress has been made in the ventilator management of severely lung-injured patients, we are still far from a fully protective mechanical ventilation. In consideration of this gap of knowledge, this doctoral thesis aimed at investigating regional lung mechanics during both inspiration and expiration, in both controlled and assisted ventilation. Particular emphasis was placed on the expiratory phase, which is involved in expiratory flow limitation, airway closure and atelectasis formation, although commonly considered non-harmful.

    A novel methodological approach has been the fundamental basis for this research project. The combination of respiratory mechanics, diaphragmatic electromyographic activity and lung imaging enabled a breath-by-breath analysis at high temporal and spatial resolution.

    In Study I, the gravitational field affected the distribution of gas and transpulmonary pressures, as previously shown. This effect differed between healthy and injured lungs. Moreover, lung injury induced a heterogeneous distribution of gas within the lungs, as well as an increased gravitational gradient in transpulmonary pressure. Study I was mainly aimed at testing the new methodological approach centred on the investigation of regional lung mechanics.

    In Study II, the focus was on assisted ventilation and the phenomenon of gas redistribution within the lungs. Large pendelluft events had been demonstrated in disproportionate inspiratory efforts. In Study II, we showed that large pendelluft resulting from pathological respiratory drive could be attenuated by high positive end expiratory pressure (PEEP). Moreover, we showed that transient and widespread small gas redistribution events occur at all times during inspiration. Assisted ventilation and high PEEP reduced the size of gas redistribution as compared with controlled ventilation and low PEEP.

    In Study III, we demonstrated a diaphragmatic expiratory contraction in lungs prone to collapse, serving to brake the expiratory flow. It preserved end expiratory lung volume (EELV) and counteracted tidal atelectasis. However, the expiratory brake induced by diaphragmatic contraction is a known cause of VIDD.

    In Study IV, we tested the effects of external expiratory resistances (ExpR). We showed that, by applying ExpR, an expiratory brake was induced. The beneficial effects on EELV were retained, while the diaphragm could quickly relax during the expiration, thus reducing the risk of VIDD.

    List of papers
    1. Effects of superimposed tissue weight on regional compliance of injured lungs
    Open this publication in new window or tab >>Effects of superimposed tissue weight on regional compliance of injured lungs
    Show others...
    2016 (English)In: Respiratory Physiology & Neurobiology, ISSN 1569-9048, E-ISSN 1878-1519, Vol. 228, p. 16-24Article in journal (Refereed) Published
    Abstract [en]

    Computed tomography (CT), together with image analysis technologies, enable the construction of regional volume (V-REG) and local transpulmonary pressure (P-TP,P-REG) maps of the lung. Purpose of this study is to assess the distribution of V-REG vs P-TP,P-REG along the gravitational axis in healthy (HL) and experimental acute lung injury conditions (eALI) at various positive end-expiratory pressures (PEEPS) and inflation volumes. Mechanically ventilated pigs underwent inspiratory hold maneuvers at increasing volumes simultaneously with lung CT scans. eALI was induced via the iv administration of oleic acid. We computed voxel-level V-REG vs P-TP,P-REG curves into eleven isogravitational planes by applying polynomial regressions. Via F-test, we determined that V-REG vs P-TP,P-REG curves derived from different anatomical planes (p-values < 1.4E-3), exposed to different PEEPs (p-values < 1.5E-5) or subtending different lung status (p-values < 3E-3) were statistically different (except for two cases of adjacent planes). Lung parenchyma exhibits different elastic behaviors based on its position and the density of superimposed tissue which can increase during lung injury.

    Keywords
    Lung compliance, Computed tomography, Acute lung injury, Image registration, Mechanical ventilation, Gravity
    National Category
    Respiratory Medicine and Allergy
    Identifiers
    urn:nbn:se:uu:diva-298837 (URN)10.1016/j.resp.2016.03.005 (DOI)000376832900003 ()26976688 (PubMedID)
    Funder
    Swedish Heart Lung Foundation
    Available from: 2016-07-11 Created: 2016-07-11 Last updated: 2019-10-07Bibliographically approved
    2. Transients of Air‐Redistribution Characterize Both Spontaneous Breathing and Mechanical Ventilation
    Open this publication in new window or tab >>Transients of Air‐Redistribution Characterize Both Spontaneous Breathing and Mechanical Ventilation
    (English)In: Article in journal (Refereed) Submitted
    National Category
    Anesthesiology and Intensive Care
    Identifiers
    urn:nbn:se:uu:diva-394304 (URN)
    Available from: 2019-10-07 Created: 2019-10-07 Last updated: 2019-10-07
    3. The Diaphragm Acts as a Brake During Expiration to Prevent Lung Collapse
    Open this publication in new window or tab >>The Diaphragm Acts as a Brake During Expiration to Prevent Lung Collapse
    Show others...
    2017 (English)In: American Journal of Respiratory and Critical Care Medicine, ISSN 1073-449X, E-ISSN 1535-4970, Vol. 195, no 12, p. 1608-1616Article in journal (Refereed) Published
    Abstract [en]

    Rationale: The diaphragm is the major inspiratory muscle and is assumed to relax during expiration. However, electrical postinspiratory activity has been observed. Whether there is an expiratory diaphragmatic contraction that preserves lung patency has yet to be explored.

    Objectives: We hypothesized the occurrence of an expiratory diaphragmatic contraction directed at stabilizing peripheral airways and preventing or reducing cyclic expiratory lung collapse.

    Methods: Mild acute respiratory distress syndrome was induced in 10 anesthetized, spontaneously breathing pigs. Lung volume was decreased by lowering end-expiratory airway pressure in a stepwise manner. We recorded the diaphragmatic electric activity during expiration, dynamic computed tomographic scans, and respiratory mechanics. In five pigs, the same protocol was repeated during mechanical ventilation after muscle paralysis.

    Measurements and Main Results: Diaphragmatic electric activity during expiration increased by decreasing end-expiratory lung volume during spontaneous breathing. This enhanced the diaphragm muscle force, to a greater extent with lower lung volume, indicating a diaphragmatic electromechanical coupling during spontaneous expiration. In turn, the resulting diaphragmatic contraction delayed and reduced the expiratory collapse and increased lung aeration compared with mechanical ventilation with muscle paralysis and absence of diaphragmatic activity.

    Conclusions: The diaphragm is an important regulator of expiration. Its expiratory activity seems to preserve lung volume and to protect against lung collapse. The loss of diaphragmatic expiratory contraction during mechanical ventilation and muscle paralysis may be a contributing factor to unsuccessful respiratory support.

    National Category
    Surgery
    Identifiers
    urn:nbn:se:uu:diva-312488 (URN)10.1164/rccm.201605-0992OC (DOI)000403383600015 ()27922742 (PubMedID)
    Funder
    Swedish Research Council, X2015-99x-22731-01-4Swedish Heart Lung Foundation
    Available from: 2017-01-10 Created: 2017-01-10 Last updated: 2019-10-07Bibliographically approved
    4. Expiratory Resistance Prevents Eccentric Diaphragm Contraction, Flow Limitation andLung Collapse
    Open this publication in new window or tab >>Expiratory Resistance Prevents Eccentric Diaphragm Contraction, Flow Limitation andLung Collapse
    Show others...
    (English)In: Article in journal (Refereed) Submitted
    National Category
    Anesthesiology and Intensive Care
    Identifiers
    urn:nbn:se:uu:diva-394303 (URN)
    Available from: 2019-10-07 Created: 2019-10-07 Last updated: 2019-10-07
  • 6.
    Pellegrini, Mariangela
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory. Univ Bari, Dept Emergency & Organ Transplant, Bari, Italy..
    Derosa, Savino
    Univ Bari, Dept Emergency & Organ Transplant, Bari, Italy..
    Tannoia, Angela
    Univ Bari, Dept Emergency & Organ Transplant, Bari, Italy..
    Rylander, Christian
    Sahlgrens Univ Hosp, Dept Anaesthesia & Intens Care Med, Gothenburg, Sweden..
    Fiore, Tommaso
    Univ Bari, Dept Emergency & Organ Transplant, Bari, Italy..
    Larsson, Anders
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Hedenstierna, Göran
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Clinical Physiology.
    Perchiazzi, Gaetano
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Clinical Physiology. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care. Univ Bari, Dept Emergency & Organ Transplant, Bari, Italy..
    Effects of superimposed tissue weight on regional compliance of injured lungs2016In: Respiratory Physiology & Neurobiology, ISSN 1569-9048, E-ISSN 1878-1519, Vol. 228, p. 16-24Article in journal (Refereed)
    Abstract [en]

    Computed tomography (CT), together with image analysis technologies, enable the construction of regional volume (V-REG) and local transpulmonary pressure (P-TP,P-REG) maps of the lung. Purpose of this study is to assess the distribution of V-REG vs P-TP,P-REG along the gravitational axis in healthy (HL) and experimental acute lung injury conditions (eALI) at various positive end-expiratory pressures (PEEPS) and inflation volumes. Mechanically ventilated pigs underwent inspiratory hold maneuvers at increasing volumes simultaneously with lung CT scans. eALI was induced via the iv administration of oleic acid. We computed voxel-level V-REG vs P-TP,P-REG curves into eleven isogravitational planes by applying polynomial regressions. Via F-test, we determined that V-REG vs P-TP,P-REG curves derived from different anatomical planes (p-values < 1.4E-3), exposed to different PEEPs (p-values < 1.5E-5) or subtending different lung status (p-values < 3E-3) were statistically different (except for two cases of adjacent planes). Lung parenchyma exhibits different elastic behaviors based on its position and the density of superimposed tissue which can increase during lung injury.

  • 7.
    Pellegrini, Mariangela
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Hedenstierna, Göran
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Clinical Physiology. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory.
    Roneus, Agneta
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Larsson, Anders S.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory.
    Perchiazzi, Gaetano
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Onset and Magnitude of Pendelluft During Spontaneous Breathing Depend on Lung Volume2018In: American Journal of Respiratory and Critical Care Medicine, ISSN 1073-449X, E-ISSN 1535-4970, Vol. 197Article in journal (Other academic)
  • 8.
    Pellegrini, Mariangela
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory. Univ Bari, Dept Emergency & Organ Transplant, Bari, Italy.
    Hedenstierna, Göran
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Clinical Physiology.
    Roneus, Agneta
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory.
    Segelsjö, Monica
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Radiology.
    Larsson, Anders
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Perchiazzi, Gaetano
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory. Univ Bari, Dept Emergency & Organ Transplant, Bari, Italy.
    The Diaphragm Acts as a Brake During Expiration to Prevent Lung Collapse2017In: American Journal of Respiratory and Critical Care Medicine, ISSN 1073-449X, E-ISSN 1535-4970, Vol. 195, no 12, p. 1608-1616Article in journal (Refereed)
    Abstract [en]

    Rationale: The diaphragm is the major inspiratory muscle and is assumed to relax during expiration. However, electrical postinspiratory activity has been observed. Whether there is an expiratory diaphragmatic contraction that preserves lung patency has yet to be explored.

    Objectives: We hypothesized the occurrence of an expiratory diaphragmatic contraction directed at stabilizing peripheral airways and preventing or reducing cyclic expiratory lung collapse.

    Methods: Mild acute respiratory distress syndrome was induced in 10 anesthetized, spontaneously breathing pigs. Lung volume was decreased by lowering end-expiratory airway pressure in a stepwise manner. We recorded the diaphragmatic electric activity during expiration, dynamic computed tomographic scans, and respiratory mechanics. In five pigs, the same protocol was repeated during mechanical ventilation after muscle paralysis.

    Measurements and Main Results: Diaphragmatic electric activity during expiration increased by decreasing end-expiratory lung volume during spontaneous breathing. This enhanced the diaphragm muscle force, to a greater extent with lower lung volume, indicating a diaphragmatic electromechanical coupling during spontaneous expiration. In turn, the resulting diaphragmatic contraction delayed and reduced the expiratory collapse and increased lung aeration compared with mechanical ventilation with muscle paralysis and absence of diaphragmatic activity.

    Conclusions: The diaphragm is an important regulator of expiration. Its expiratory activity seems to preserve lung volume and to protect against lung collapse. The loss of diaphragmatic expiratory contraction during mechanical ventilation and muscle paralysis may be a contributing factor to unsuccessful respiratory support.

  • 9.
    Pellegrini, Mariangela
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory.
    Roneus, Agneta
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory.
    Fiore, T.
    Univ Bari, Bari, Italy..
    Hedenstierna, Göran
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Clinical Physiology.
    Larsson, Anders
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Perchiazzi, Gaetano
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory. Univ Bari, Bari, Italy..
    Can Expiratory Electrical Diaphragmatic Activity Guide Setting Of Positive End-Expiratory Pressure During Spontaneous Breathing In Acute Respiratory Failure?2015In: American Journal of Respiratory and Critical Care Medicine, ISSN 1073-449X, E-ISSN 1535-4970, Vol. 191Article in journal (Other academic)
  • 10.
    Perchiazzi, G
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care. Bari Univ, Dept Emergency & Organ Transplant, Bari, Italy.
    Rylander, Christian
    Sahlgrens Univ Hosp, Dept Anaesthesia & Intens Care Med, Gothenburg, Sweden.
    Pellegrini, Mariangela
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care. Bari Univ, Dept Emergency & Organ Transplant, Bari, Italy.
    Larsson, Anders
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory.
    Hedenstierna, Göran
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Clinical Physiology.
    Robustness of two different methods of monitoring respiratory system compliance during mechanical ventilation.2017In: Medical and Biological Engineering and Computing, ISSN 0140-0118, E-ISSN 1741-0444, Vol. 55, no 10, p. 1819-1828Article in journal (Refereed)
    Abstract [en]

    Robustness measures the performance of estimation methods when they work under non-ideal conditions. We compared the robustness of artificial neural networks (ANNs) and multilinear fitting (MLF) methods in estimating respiratory system compliance (C RS) during mechanical ventilation (MV). Twenty-four anaesthetized pigs underwent MV. Airway pressure, flow and volume were recorded at fixed intervals after the induction of acute lung injury. After consecutive mechanical breaths, an inspiratory pause (BIP) was applied in order to calculate CRS using the interrupter technique. From the breath preceding the BIP, ANN and MLF had to compute CRS in the presence of two types of perturbations: transient sensor disconnection (TD) and random noise (RN). Performance of the two methods was assessed according to Bland and Altman. The ANN presented a higher bias and scatter than MLF during the application of RN, except when RN was lower than 2% of peak airway pressure. During TD, MLF algorithm showed a higher bias and scatter than ANN. After the application of RN, ANN and MLF maintain a stable performance, although MLF shows better results. ANNs have a more stable performance and yield a more robust estimation of C RS than MLF in conditions of transient sensor disconnection.

  • 11.
    Perchiazzi, Gaetano
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Pellegrini, Mariangela
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Hedenstierna, Göran
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Clinical Physiology. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory.
    Roneus, Agneta
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory.
    Larsson, Anders S.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory.
    Multiple Transients of Local Gas Redistribution During Spontaneous Breathing Are Influenced by Ventilatory Settings2018In: American Journal of Respiratory and Critical Care Medicine, ISSN 1073-449X, E-ISSN 1535-4970, Vol. 197Article in journal (Other academic)
  • 12.
    Perchiazzi, Gaetano
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory.
    Pellegrini, Mariangela
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory.
    Lantz, Hannes
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory.
    Hedenstierna, Göran
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Clinical Physiology.
    Larsson, Anders
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory.
    High PEEP Reduces Recruitment/Derecruitment During Neurally Adjusted Ventilatory Assist in Mild Experimental ARDS2016In: American Journal of Respiratory and Critical Care Medicine, ISSN 1073-449X, E-ISSN 1535-4970, Vol. 193, article id A5226Article in journal (Other academic)
  • 13.
    Perchiazzi, Gaetano
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care. Department of Emergency and Organ Transplant, Section of Anaesthesia and Intensive Care Medicine, University of Bari, Italy.
    Rylander, Christian
    Pellegrini, Mariangela
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory. Department of Emergency and Organ Transplant, Section of Anaesthesia and Intensive Care Medicine, University of Bari, Italy.
    Larsson, Anders
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Hedenstierna, Göran
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Clinical Physiology.
    Monitoring of total positive end-expiratory pressure during mechanical ventilation by artificial neural networks2017In: Journal of clinical monitoring and computing, ISSN 1387-1307, E-ISSN 1573-2614, Vol. 31, no 3, p. 551-559Article in journal (Refereed)
    Abstract [en]

    Ventilation treatment of acute lung injury (ALI) requires the application of positive airway pressure at the end of expiration (PEEPapp) to avoid lung collapse. However, the total pressure exerted on the alveolar walls (PEEPtot) is the sum of PEEPapp and intrinsic PEEP (PEEPi), a hidden component. To measure PEEPtot, ventilation must be discontinued with an end-expiratory hold maneuver (EEHM). We hypothesized that artificial neural networks (ANN) could estimate the PEEPtot from flow and pressure tracings during ongoing mechanical ventilation. Ten pigs were mechanically ventilated, and the time constant of their respiratory system (τRS) was measured. We shortened their expiratory time (TE) according to multiples of τRS, obtaining different respiratory patterns (Rpat). Pressure (PAW) and flow (V'AW) at the airway opening during ongoing mechanical ventilation were simultaneously recorded, with and without the addition of external resistance. The last breath of each Rpat included an EEHM, which was used to compute the reference PEEPtot. The entire protocol was repeated after the induction of ALI with i.v. injection of oleic acid, and 382 tracings were obtained. The ANN had to extract the PEEPtot, from the tracings without an EEHM. ANN agreement with reference PEEPtot was assessed with the Bland-Altman method. Bland Altman analysis of estimation error by ANN showed -0.40 ± 2.84 (expressed as bias ± precision) and ±5.58 as limits of agreement (data expressed as cmH2O). The ANNs estimated the PEEPtot well at different levels of PEEPapp under dynamic conditions, opening up new possibilities in monitoring PEEPi in critically ill patients who require ventilator treatment.

  • 14.
    Scaramuzzo, Gaetano
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory. Univ Ferrara, Dept Morphol Surg & Expt Med, Ferrara, Italy.
    Broche, Ludovic
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory. European Synchrotron Radiat Facil, Grenoble, France;Grenoble Alpes Univ, Synchrotron Radiat Biomed STROBE Lab, INSERM UA7, Amiens, France.
    Pellegrini, Mariangela
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Porra, Liisa
    Univ Helsinki, Fac Math & Nat Sci, Dept Phys, Helsinki, Finland;Univ Helsinki, Cent Hosp, Helsinki, Finland.
    Derosa, Savino
    Univ Bari Aldo Moro, Dept Emergency & Organ Transplant, Bari, Italy.
    Tannoia, Angela Principia
    Univ Bari Aldo Moro, Dept Emergency & Organ Transplant, Bari, Italy.
    Marzullo, Andrea
    Univ Bari Aldo Moro, Dept Emergency & Organ Transplant, Bari, Italy.
    Batista Borges, João
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory. Kings Coll London, Fac Sci & Med, Ctr Human & Appl Physiol Sci, London, England.
    Bayat, Sam
    Grenoble Alpes Univ, Synchrotron Radiat Biomed STROBE Lab, INSERM UA7, Amiens, France.
    Bravin, Alberto
    European Synchrotron Radiat Facil, Grenoble, France.
    Larsson, Anders
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory.
    Perchiazzi, Gaetano
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Regional Behavior of Airspaces During Positive Pressure Reduction Assessed by Synchrotron Radiation Computed Tomography2019In: Frontiers in Physiology, ISSN 1664-042X, E-ISSN 1664-042X, Vol. 10, article id 719Article in journal (Refereed)
    Abstract [en]

    Introduction: The mechanisms of lung inflation and deflation are only partially known. Ventilatory strategies to support lung function rely upon the idea that lung alveoli are isotropic balloons that progressively inflate or deflate and that lung pressure/volume curves derive only by the interplay of critical opening pressures, critical closing pressures, lung history, and position of alveoli inside the lung. This notion has been recently challenged by subpleural microscopy, magnetic resonance, and computed tomography (CT). Phase-contrast synchrotron radiation CT (PC-SRCT) can yield in vivo images at resolutions higher than conventional CT.

    Objectives: We aimed to assess the numerosity (ASden) and the extension of the surface of airspaces (ASext) in healthy conditions at different volumes, during stepwise lung deflation, in concentric regions of the lung. Methods: The study was conducted in seven anesthetized New Zealand rabbits. They underwent PC-SRCT scans (resolution of 47.7 mu m) of the lung at five decreasing positive end expiratory pressure (PEEP) levels of 12, 9, 6, 3, and 0 cmH(2)O during end-expiratory holds. Three concentric regions of interest (ROIs) of the lung were studied: subpleural, mantellar, and core. The images were enhanced by phase contrast algorithms. ASden and ASext were computed by using the Image Processing Toolbox for MatLab. Statistical tests were used to assess any significant difference determined by PEEP or ROI on ASden and ASext.

    Results: When reducing PEEP, in each ROI the ASden significantly decreased. Conversely, ASext variation was not significant except for the core ROI. In the latter, the angular coefficient of the regression line was significantly low.

    Conclusion: The main mechanism behind the decrease in lung volume at PEEP reduction is derecruitment. In our study involving lung regions laying on isogravitational planes and thus equally influenced by gravitational forces, airspace numerosity and extension of surface depend on the local mechanical properties of the lung.

  • 15.
    Scaramuzzo, Gaetano
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory. Ferrara Univ, Dept Morphol Surg & Expt Med, I-44121 Ferrara, Italy;.
    Broche, Ludovic
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory.
    Pellegrini, Mariangela
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Hedenstierna laboratory. Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Porra, Liisa
    Univ Helsinki, Dept Phys, FI-00014 Helsinki, Finland;Helsinki Univ Hosp, FI-00029 Helsinki, Finland.
    Derosa, Savino
    Bari Univ, Dept Emergency & Organ Transplant, I-70124 Bari, Italy.
    Tannoia, Angela Principia
    Bari Univ, Dept Emergency & Organ Transplant, I-70124 Bari, Italy.
    Marzullo, Andrea
    Bari Univ, Dept Emergency & Organ Transplant, I-70124 Bari, Italy.
    Borges, Joao Batista
    Kings Coll London, Fac Sci & Med, Ctr Human & Appl Physiol Sci, London WC2R 2LS, England.
    Bayat, Sam
    European Synchrotron Radiat Facil, F-38043 Grenoble, France;Univ Grenoble Alpes, Synchrotron Radiat Biomed STROBE Lab, INSERM UA7, F-38043 Grenoble, France.
    Bravin, Alberto
    European Synchrotron Radiat Facil, F-38043 Grenoble, France.
    Larsson, Anders
    Uppsala Univ, Dept Surg Sci, Hedenstierna Lab, S-75185 Uppsala, Sweden.
    Perchiazzi, Gaetano
    Uppsala Univ, Dept Surg Sci, Hedenstierna Lab, S-75185 Uppsala, Sweden;Uppsala Univ Hosp, Dept Anesthesia & Intens Care, S-75185 Uppsala, Sweden.
    The Effect of Positive End-Expiratory Pressure on Lung Micromechanics Assessed by Synchrotron Radiation Computed Tomography in an Animal Model of ARDS2019In: JOURNAL OF CLINICAL MEDICINE, ISSN 2077-0383, Vol. 8, no 8, article id 1117Article in journal (Refereed)
    Abstract [en]

    Modern ventilatory strategies are based on the assumption that lung terminal airspaces act as isotropic balloons that progressively accommodate gas. Phase contrast synchrotron radiation computed tomography (PCSRCT) has recently challenged this concept, showing that in healthy lungs, deflation mechanisms are based on the sequential de-recruitment of airspaces. Using PCSRCT scans in an animal model of acute respiratory distress syndrome (ARDS), this study examined whether the numerosity (ASnum) and dimension (ASdim) of lung airspaces change during a deflation maneuver at decreasing levels of positive end-expiratory pressure (PEEP) at 12, 9, 6, 3, and 0 cmH(2)O. Deflation was associated with significant reduction of ASdim both in the whole lung section (passing from from 13.1 +/- 2.0 at PEEP 12 to 7.6 +/- 4.2 voxels at PEEP 0) and in single concentric regions of interest (ROIs). However, the regression between applied PEEP and ASnum was significant in the whole slice (ranging from 188 +/- 52 at PEEP 12 to 146.4 +/- 96.7 at PEEP 0) but not in the single ROIs. This mechanism of deflation in which reduction of ASdim is predominant, differs from the one observed in healthy conditions, suggesting that the peculiar alveolar micromechanics of ARDS might play a role in the deflation process.

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