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Batista Borges, João
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Publications (10 of 48) Show all publications
Broche, L., Pisa, P., Porra, L., Degrugilliers, L., Bravin, A., Pellegrini, M., . . . Bayat, S. (2019). Individual Airway Closure Characterized In Vivo by Phase-Contrast CT Imaging in Injured Rabbit Lung. Critical Care Medicine, 47(9), E774-E781
Open this publication in new window or tab >>Individual Airway Closure Characterized In Vivo by Phase-Contrast CT Imaging in Injured Rabbit Lung
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2019 (English)In: Critical Care Medicine, ISSN 0090-3493, E-ISSN 1530-0293, Vol. 47, no 9, p. E774-E781Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
LIPPINCOTT WILLIAMS & WILKINS, 2019
Keywords
airway closure, mechanical ventilation, phase-contrast imaging, respiratory distress syndrome, adult, tomography, x-ray computed, ventilator-induced lung injury
National Category
Anesthesiology and Intensive Care
Identifiers
urn:nbn:se:uu:diva-394204 (URN)10.1097/CCM.0000000000003838 (DOI)000484224200007 ()31162202 (PubMedID)
Available from: 2019-10-04 Created: 2019-10-04 Last updated: 2019-10-04Bibliographically approved
Reinius, H., Batista Borges, J., Engström, J., Ahlgren, O., Lennmyr, F., Larsson, A. & Fredén, F. (2019). Optimal PEEP during one-lung ventilation with capnothorax: An experimental study. Acta Anaesthesiologica Scandinavica, 63(2), 222-231
Open this publication in new window or tab >>Optimal PEEP during one-lung ventilation with capnothorax: An experimental study
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2019 (English)In: Acta Anaesthesiologica Scandinavica, ISSN 0001-5172, E-ISSN 1399-6576, Vol. 63, no 2, p. 222-231Article in journal (Refereed) Published
Abstract [en]

Background: One‐lung ventilation (OLV) with induced capnothorax carries the risk of severely impaired ventilation and circulation. Optimal PEEP may mitigate the physiological perturbations during these conditions.

Methods: Right‐sided OLV with capnothorax (16 cm H2O) on the left side was initiated in eight anesthetized, muscle‐relaxed piglets. A recruitment maneuver and a decremental PEEP titration from PEEP 20 cm H2O to zero end‐expiratory pressure (ZEEP) was performed. Regional ventilation and perfusion were studied with electrical impedance tomography and computer tomography of the chest was used. End‐expiratory lung volume and hemodynamics were recorded and.

Results: PaO2 peaked at PEEP 12 cm H2O (49 ± 14 kPa) and decreased to 11 ± 5 kPa at ZEEP (P < 0.001). PaCO2 was 9.5 ± 1.3 kPa at 20 cm H2O PEEP and did not change when PEEP step‐wise was reduced to 12 cm H2O PaCO2. At lower PEEP, PaCO2 increased markedly. The ventilatory driving pressure was lowest at PEEP 14 cm H2O (19.6 ± 5.8 cm H2O) and increased to 38.3 ± 6.1 cm H2O at ZEEP (P < 0.001). When reducing PEEP below 12‐14 cm H2O ventilation shifted from the dependent to the nondependent regions of the ventilated lung (P = 0.003), and perfusion shifted from the ventilated to the nonventilated lung (P = 0.02).

Conclusion: Optimal PEEP was 12‐18 cm H2O and probably relates to capnothorax insufflation pressure. With suboptimal PEEP, ventilation/perfusion mismatch in the ventilated lung and redistribution of blood flow to the nonventilated lung occurred.

Keywords
anesthesia, capnothorax, cardio-thoracic surgery, one lung ventilation, optimal PEEP, PEEP titration
National Category
Anesthesiology and Intensive Care
Research subject
Anaesthesiology and Intensive Care
Identifiers
urn:nbn:se:uu:diva-268620 (URN)10.1111/aas.13247 (DOI)000454814700012 ()30132806 (PubMedID)
Funder
Swedish Heart Lung Foundation
Note

Title in thesis list of papers: Optimal PEEP during one lung ventilation with capnothorax. An experimental study

Available from: 2015-12-08 Created: 2015-12-08 Last updated: 2019-01-31Bibliographically approved
Scaramuzzo, G., Broche, L., Pellegrini, M., Porra, L., Derosa, S., Tannoia, A. P., . . . Perchiazzi, G. (2019). Regional Behavior of Airspaces During Positive Pressure Reduction Assessed by Synchrotron Radiation Computed Tomography. Frontiers in Physiology, 10, Article ID 719.
Open this publication in new window or tab >>Regional Behavior of Airspaces During Positive Pressure Reduction Assessed by Synchrotron Radiation Computed Tomography
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2019 (English)In: Frontiers in Physiology, ISSN 1664-042X, E-ISSN 1664-042X, Vol. 10, article id 719Article in journal (Refereed) Published
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.

Keywords
recruitment, VILI, alveoli, kinetics, SRCT
National Category
Respiratory Medicine and Allergy Anesthesiology and Intensive Care
Identifiers
urn:nbn:se:uu:diva-389594 (URN)10.3389/fphys.2019.00719 (DOI)000471313900001 ()31231245 (PubMedID)
Funder
Swedish Research Council, K2015-99X-22731-01-4Swedish Heart Lung Foundation
Available from: 2019-07-25 Created: 2019-07-25 Last updated: 2019-07-25Bibliographically approved
Retamal, J., Hurtado, D., Villarroel, N., Bruhn, A., Bugedo, G., Amato, M. B., . . . Batista Borges, J. (2018). Does Regional Lung Strain Correlate With Regional Inflammation in Acute Respiratory Distress Syndrome During Nonprotective Ventilation?: An Experimental Porcine Study. Critical Care Medicine, 46(6), e591-e599
Open this publication in new window or tab >>Does Regional Lung Strain Correlate With Regional Inflammation in Acute Respiratory Distress Syndrome During Nonprotective Ventilation?: An Experimental Porcine Study
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2018 (English)In: Critical Care Medicine, ISSN 0090-3493, E-ISSN 1530-0293, Vol. 46, no 6, p. e591-e599Article in journal (Refereed) Published
Abstract [en]

OBJECTIVE: It is known that ventilator-induced lung injury causes increased pulmonary inflammation. It has been suggested that one of the underlying mechanisms may be strain. The aim of this study was to investigate whether lung regional strain correlates with regional inflammation in a porcine model of acute respiratory distress syndrome.

DESIGN: Retrospective analysis of CT images and positron emission tomography images using [18F]fluoro-2-deoxy-D-glucose.

SETTING: University animal research laboratory.

SUBJECTS: Seven piglets subjected to experimental acute respiratory distress syndrome and five ventilated controls.

INTERVENTIONS: Acute respiratory distress syndrome was induced by repeated lung lavages, followed by 210 minutes of injurious mechanical ventilation using low positive end-expiratory pressures (mean, 4 cm H2O) and high inspiratory pressures (mean plateau pressure, 45 cm H2O). All animals were subsequently studied with CT scans acquired at end-expiration and end-inspiration, to obtain maps of volumetric strain (inspiratory volume - expiratory volume)/expiratory volume, and dynamic positron emission tomography imaging. Strain maps and positron emission tomography images were divided into 10 isogravitational horizontal regions-of-interest, from which spatial correlation was calculated for each animal.

MEASUREMENTS AND MAIN RESULTS: The acute respiratory distress syndrome model resulted in a decrease in respiratory system compliance (20.3 ± 3.4 to 14.0 ± 4.9 mL/cm H2O; p < 0.05) and oxygenation (PaO2/FIO2, 489 ± 80 to 92 ± 59; p < 0.05), whereas the control animals did not exhibit changes. In the acute respiratory distress syndrome group, strain maps showed a heterogeneous distribution with a greater concentration in the intermediate gravitational regions, which was similar to the distribution of [18F]fluoro-2-deoxy-D-glucose uptake observed in the positron emission tomography images, resulting in a positive spatial correlation between both variables (median R2 = 0.71 [0.02-0.84]; p < 0.05 in five of seven animals), which was not observed in the control animals.

CONCLUSION: In this porcine acute respiratory distress syndrome model, regional lung strain was spatially correlated with regional inflammation, supporting that strain is a relevant and prominent determinant of ventilator-induced lung injury.

Keywords
acute lung injury, positron emission tomography, respiration, artificial, tomography, x-ray computed
National Category
Anesthesiology and Intensive Care
Research subject
Physiology
Identifiers
urn:nbn:se:uu:diva-365775 (URN)10.1097/CCM.0000000000003072 (DOI)000439575100016 ()29528946 (PubMedID)
Funder
Swedish Heart Lung FoundationSwedish Research Council, K2015-99X-22731-01-4
Available from: 2018-11-13 Created: 2018-11-13 Last updated: 2019-06-28Bibliographically approved
Bachmann, M. C., Morais, C., Bugedo, G., Bruhn, A., Morales, A., Batista Borges, J., . . . Retamal, J. (2018). Electrical impedance tomography in acute respiratory distress syndrome. Critical Care, 22, Article ID 263.
Open this publication in new window or tab >>Electrical impedance tomography in acute respiratory distress syndrome
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2018 (English)In: Critical Care, ISSN 1364-8535, E-ISSN 1466-609X, Vol. 22, article id 263Article, review/survey (Refereed) Published
Abstract [en]

Acute respiratory distress syndrome (ARDS) is a clinical entity that acutely affects the lung parenchyma, and is characterized by diffuse alveolar damage and increased pulmonary vascular permeability. Currently, computed tomography (CT) is commonly used for classifying and prognosticating ARDS. However, performing this examination in critically ill patients is complex, due to the need to transfer these patients to the CT room. Fortunately, new technologies have been developed that allow the monitoring of patients at the bedside. Electrical impedance tomography (EIT) is a monitoring tool that allows one to evaluate at the bedside the distribution of pulmonary ventilation continuously, in real time, and which has proven to be useful in optimizing mechanical ventilation parameters in critically ill patients. Several clinical applications of EIT have been developed during the last years and the technique has been generating increasing interest among researchers. However, among clinicians, there is still a lack of knowledge regarding the technical principles of EIT and potential applications in ARDS patients. The aim of this review is to present the characteristics, technical concepts, and clinical applications of EIT, which may allow better monitoring of lung function during ARDS.

Place, publisher, year, edition, pages
BioMed Central, 2018
Keywords
Electrical impedance tomography, Acute respiratory distress syndrome, Mechanical ventilation, Ventilation distribution, Lung imaging
National Category
Anesthesiology and Intensive Care
Identifiers
urn:nbn:se:uu:diva-369945 (URN)10.1186/s13054-018-2195-6 (DOI)000448393900003 ()30360753 (PubMedID)
Available from: 2018-12-18 Created: 2018-12-18 Last updated: 2018-12-18Bibliographically approved
Morais, C. C. A., Koyama, Y., Yoshida, T., Plens, G. M., Gomes, S., Lima, C. A. S., . . . Fujino, Y. (2018). High Positive End-Expiratory Pressure Renders Spontaneous Effort Noninjurious. American Journal of Respiratory and Critical Care Medicine, 197(10), 1285-1296
Open this publication in new window or tab >>High Positive End-Expiratory Pressure Renders Spontaneous Effort Noninjurious
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2018 (English)In: American Journal of Respiratory and Critical Care Medicine, ISSN 1073-449X, E-ISSN 1535-4970, Vol. 197, no 10, p. 1285-1296Article in journal (Refereed) Published
Abstract [en]

Rationale: In acute respiratory distress syndrome (ARDS), atelectatic solid-like lung tissue impairs transmission of negative swings in pleural pressure (Ppl) that result from diaphragmatic contraction. The localization of more negative Ppl proportionally increases dependent lung stretch by drawing gas either from other lung regions (e.g., nondependent lung [pendelluft]) or from the ventilator. Lowering the level of spontaneous effort and/or converting solid-like to fluid-like lung might render spontaneous effort noninjurious.

Objectives: To determine whether spontaneous effort increases dependent lung injury, and whether such injury would be reduced by recruiting atelectatic solid-like lung with positive end-expiratory pressure (PEEP).

Methods: Established models of severe ARDS (rabbit, pig) were used. Regional histology (rabbit), inflammation (positron emission tomography; pig), regional inspiratory Ppl (intrabronchial balloon manometry), and stretch (electrical impedance tomography; pig) were measured. Respiratory drive was evaluated in 11 patients with ARDS.

Measurements and Main Results: Although injury during muscle paralysis was predominantly in nondependent and middle lung regions at low (vs. high) PEEP, strong inspiratory effort increased injury (indicated by positron emission tomography and histology) in dependent lung. Stronger effort (vs. muscle paralysis) caused local overstretch and greater tidal recruitment in dependent lung, where more negative Ppl was localized and greater stretch was generated. In contrast, high PEEP minimized lung injury by more uniformly distributing negative Ppl, and lowering the magnitude of spontaneous effort (i.e., deflection in esophageal pressure observed in rabbits, pigs, and patients).

Conclusions: Strong effort increased dependent lung injury, where higher local lung stress and stretch was generated; effort-dependent lung injury was minimized by high PEEP in severe ARDS, which may offset need for paralysis.

Place, publisher, year, edition, pages
AMER THORACIC SOC, 2018
Keywords
acute respiratory distress syndrome, spontaneous breathing, ventilator-induced lung injury, PEEP
National Category
Respiratory Medicine and Allergy Anesthesiology and Intensive Care
Identifiers
urn:nbn:se:uu:diva-357751 (URN)10.1164/rccm.201706-1244OC (DOI)000432215400012 ()29323536 (PubMedID)
Available from: 2018-08-22 Created: 2018-08-22 Last updated: 2018-08-22Bibliographically approved
Batista Borges, J. (2018). The Plausibility of "Bronchiolotrauma" [Letter to the editor]. American Journal of Respiratory and Critical Care Medicine, 197(8), 1086-1087
Open this publication in new window or tab >>The Plausibility of "Bronchiolotrauma"
2018 (English)In: American Journal of Respiratory and Critical Care Medicine, ISSN 1073-449X, E-ISSN 1535-4970, Vol. 197, no 8, p. 1086-1087Article in journal, Letter (Refereed) Published
Place, publisher, year, edition, pages
AMER THORACIC SOC, 2018
National Category
Respiratory Medicine and Allergy
Identifiers
urn:nbn:se:uu:diva-357165 (URN)10.1164/rccm.201708-1685LE (DOI)000430039900024 ()29186663 (PubMedID)
Available from: 2018-08-15 Created: 2018-08-15 Last updated: 2018-08-15Bibliographically approved
Broche, L., Perchiazzi, G., Porra, L., Tannoia, A., Pellegrini, M., Derosa, S., . . . Bayat, S. (2017). Dynamic Mechanical Interactions Between Neighboring Airspaces Determine Cyclic Opening and Closure in Injured Lung. Critical Care Medicine, 45(4), 687-694
Open this publication in new window or tab >>Dynamic Mechanical Interactions Between Neighboring Airspaces Determine Cyclic Opening and Closure in Injured Lung
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2017 (English)In: Critical Care Medicine, ISSN 0090-3493, E-ISSN 1530-0293, Vol. 45, no 4, p. 687-694Article in journal (Refereed) Published
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.

Keywords
acute respiratory distress syndrome, assisted ventilation, imaging/computed tomography, pulmonary oedema, synchrotron
National Category
Anesthesiology and Intensive Care
Identifiers
urn:nbn:se:uu:diva-321336 (URN)10.1097/CCM.0000000000002234 (DOI)000396798700016 ()28107207 (PubMedID)
Funder
Swedish Heart Lung FoundationSwedish Research CouncilNIH (National Institute of Health)
Available from: 2017-05-31 Created: 2017-05-31 Last updated: 2017-05-31Bibliographically approved
Kretzschmar, M., Kozian, A., Baumgardner, J. E., Borges, J. B., Hedenstierna, G., Larsson, A., . . . Schilling, T. (2017). Effect of Bronchoconstriction-induced Ventilation-Perfusion Mismatch on Uptake and Elimination of Isoflurane and Desflurane. Anesthesiology, 127(5), 800-812
Open this publication in new window or tab >>Effect of Bronchoconstriction-induced Ventilation-Perfusion Mismatch on Uptake and Elimination of Isoflurane and Desflurane
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2017 (English)In: Anesthesiology, ISSN 0003-3022, E-ISSN 1528-1175, Vol. 127, no 5, p. 800-812Article in journal (Refereed) Published
Abstract [en]

BACKGROUND: Increasing numbers of patients with obstructive lung diseases need anesthesia for surgery. These conditions are associated with pulmonary ventilation/perfusion (VA/Q) mismatch affecting kinetics of volatile anesthetics. Pure shunt might delay uptake of less soluble anesthetic agents but other forms of VA/Q scatter have not yet been examined. Volatile anesthetics with higher blood solubility would be less affected by VA/Q mismatch. We therefore compared uptake and elimination of higher soluble isoflurane and less soluble desflurane in a piglet model.

METHODS: Juvenile piglets (26.7 ± 1.5 kg) received either isoflurane (n = 7) or desflurane (n = 7). Arterial and mixed venous blood samples were obtained during wash-in and wash-out of volatile anesthetics before and during bronchoconstriction by methacholine inhalation (100 μg/ml). Total uptake and elimination were calculated based on partial pressure measurements by micropore membrane inlet mass spectrometry and literature-derived partition coefficients and assumed end-expired to arterial gradients to be negligible. VA/Q distribution was assessed by the multiple inert gas elimination technique.

RESULTS: Before methacholine inhalation, isoflurane arterial partial pressures reached 90% of final plateau within 16 min and decreased to 10% after 28 min. By methacholine nebulization, arterial uptake and elimination delayed to 35 and 44 min. Desflurane needed 4 min during wash-in and 6 min during wash-out, but with bronchoconstriction 90% of both uptake and elimination was reached within 15 min.

CONCLUSIONS: Inhaled methacholine induced bronchoconstriction and inhomogeneous VA/Q distribution. Solubility of inhalational anesthetics significantly influenced pharmacokinetics: higher soluble isoflurane is less affected than fairly insoluble desflurane, indicating different uptake and elimination during bronchoconstriction.

National Category
Anesthesiology and Intensive Care
Identifiers
urn:nbn:se:uu:diva-334179 (URN)10.1097/ALN.0000000000001847 (DOI)000414634700010 ()28857808 (PubMedID)
Funder
Swedish Research Council, X2015-99x-22731-01-04
Available from: 2017-11-21 Created: 2017-11-21 Last updated: 2018-02-16Bibliographically approved
Santos, A., Gomez-Peñalver, E., Monge-Garcia, M. I., Retamal, J., Batista Borges, J., Tusman, G., . . . Suarez-Sipmann, F. (2017). Effects on Pulmonary Vascular Mechanics of Two Different Lung-Protective Ventilation Strategies in an Experimental Model of Acute Respiratory Distress Syndrome. Critical Care Medicine, 45(11), e1157-e1164
Open this publication in new window or tab >>Effects on Pulmonary Vascular Mechanics of Two Different Lung-Protective Ventilation Strategies in an Experimental Model of Acute Respiratory Distress Syndrome
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2017 (English)In: Critical Care Medicine, ISSN 0090-3493, E-ISSN 1530-0293, Vol. 45, no 11, p. e1157-e1164Article in journal (Refereed) Published
Abstract [en]

OBJECTIVES: To compare the effects of two lung-protective ventilation strategies on pulmonary vascular mechanics in early acute respiratory distress syndrome.

DESIGN: Experimental study.

SETTING: University animal research laboratory.

SUBJECTS: Twelve pigs (30.8 ± 2.5 kg).

INTERVENTIONS: Acute respiratory distress syndrome was induced by repeated lung lavages and injurious mechanical ventilation. Thereafter, animals were randomized to 4 hours ventilation according to the Acute Respiratory Distress Syndrome Network protocol or to an open lung approach strategy. Pressure and flow sensors placed at the pulmonary artery trunk allowed continuous assessment of pulmonary artery resistance, effective elastance, compliance, and reflected pressure waves. Respiratory mechanics and gas exchange data were collected.

MEASUREMENTS AND MAIN RESULTS: Acute respiratory distress syndrome led to pulmonary vascular mechanics deterioration. Four hours after randomization, pulmonary vascular mechanics was similar in Acute Respiratory Distress Syndrome Network and open lung approach: resistance (578 ± 252 vs 626 ± 153 dyn.s/cm; p = 0.714), effective elastance, (0.63 ± 0.22 vs 0.58 ± 0.17 mm Hg/mL; p = 0.710), compliance (1.19 ± 0.8 vs 1.50 ± 0.27 mL/mm Hg; p = 0.437), and reflection index (0.36 ± 0.04 vs 0.34 ± 0.09; p = 0.680). Open lung approach as compared to Acute Respiratory Distress Syndrome Network was associated with improved dynamic respiratory compliance (17.3 ± 2.6 vs 10.5 ± 1.3 mL/cm H2O; p < 0.001), driving pressure (9.6 ± 1.3 vs 19.3 ± 2.7 cm H2O; p < 0.001), and venous admixture (0.05 ± 0.01 vs 0.22 ± 0.03, p < 0.001) and lower mean pulmonary artery pressure (26 ± 3 vs 34 ± 7 mm Hg; p = 0.045) despite of using a higher positive end-expiratory pressure (17.4 ± 0.7 vs 9.5 ± 2.4 cm H2O; p < 0.001). Cardiac index, however, was lower in open lung approach (1.42 ± 0.16 vs 2.27 ± 0.48 L/min; p = 0.005).

CONCLUSIONS: In this experimental model, Acute Respiratory Distress Syndrome Network and open lung approach affected pulmonary vascular mechanics similarly. The use of higher positive end-expiratory pressures in the open lung approach strategy did not worsen pulmonary vascular mechanics, improved lung mechanics, and gas exchange but at the expense of a lower cardiac index.

National Category
Respiratory Medicine and Allergy
Identifiers
urn:nbn:se:uu:diva-334177 (URN)10.1097/CCM.0000000000002701 (DOI)000417107000007 ()28872540 (PubMedID)
Funder
Swedish Research Council, K2015-99X-22731-01-4Swedish Heart Lung FoundationEU, FP7, Seventh Framework Programme, 291820
Available from: 2017-11-21 Created: 2017-11-21 Last updated: 2018-03-09Bibliographically approved
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