Journal article
Abrupt Deflation after Sustained Inflation Causes Lung Injury
American journal of respiratory and critical care medicine, Vol.198(9), pp.1165-1176
11/01/2018
DOI: 10.1164/rccm.201801-0178OC
PMID: 29902384
Abstract
Rationale: Ventilator management in acute respiratory distress syndrome usually focuses on setting parameters, but events occurring at ventilator disconnection are not well understood.
Objectives: To determine if abrupt deflation after sustained inflation causes lung injury.
Methods: Male Sprague-Dawley rats were ventilated (low V-T, 6 ml/kg) and randomized to control (n = 6; positive end-expiratory pressure [PEEP], 3 cm H2O; 100 min) or intervention (n = 6; PEEP, 3-11 cm H2O over 70 min; abrupt deflation to zero PEEP; ventilation for 30 min). Lung function and injury was assessed, scanning electron microscopy performed, and microvascular leak timed by Evans blue dye (n = 4/group at 0, 2, 5, 10, and 20 min after deflation). Hemodynamic assessment included systemic arterial pressure (n = 6), echocardiography (n = 4), and right (n = 6) and left ventricular pressures (n = 6).
Measurements and Main Results: Abrupt deflation after sustained inflation (vs. control) caused acute lung dysfunction (compliance 0.48 +/- 1.0 vs. 0.82 +/- 0.2 m/cm H2O, oxygen saturation as measured by pulse oximetry 67 +/- 23.5 vs. 91 +/- 4.4%; P < 0.05) and injury (wet/dry ratio 6.1 +/- 0.6 vs. 4.6 +/- 0.4; P < 0.01). Vascular leak was absent before deflation and maximal 5-10 minutes thereafter; injury was predominantly endothelial. At deflation, left ventricular preload, systemic blood pressure, and left ventricular end-diastolic pressure increased precipitously in proportion to the degree of injury. Injury caused later right ventricular failure. Sodium nitroprusside prevented the increase in systemic blood pressure and left ventricular end-diastolic pressure associated with deflation, and prevented injury. Injury did not occur with gradual deflation.
Conclusions: Abrupt deflation after sustained inflation can cause acute lung injury. It seems to be mediated by acute left ventricular decompensation (caused by increased left ventricular preload and afterload) that elevates pulmonary microvascular pressure; this directly injures the endothelium and causes edema, which is potentiated by the surge in pulmonary perfusion.
Details
- Title: Subtitle
- Abrupt Deflation after Sustained Inflation Causes Lung Injury
- Creators
- Bhushan H. Katira - Translational Research InstituteDoreen Engelberts - Translational Research InstituteGail Otulakowski - Translational Research InstituteRegan E. Giesinger - University of TorontoTakeshi Yoshida - Translational Research InstituteMartin Post - Translational Research InstituteWolfgang M. Kuebler - University of TorontoKim A. Connelly - St. Michael's HospitalBrian P. Kavanagh - Translational Research Institute
- Resource Type
- Journal article
- Publication Details
- American journal of respiratory and critical care medicine, Vol.198(9), pp.1165-1176
- Publisher
- Amer Thoracic Soc
- DOI
- 10.1164/rccm.201801-0178OC
- PMID
- 29902384
- ISSN
- 1073-449X
- eISSN
- 1535-4970
- Number of pages
- 12
- Grant note
- Ministry of Research and Innovation and Science, Ontario Canadian Institutes of Health Research; Canadian Institutes of Health Research (CIHR)
- Language
- English
- Date published
- 11/01/2018
- Academic Unit
- Stead Family Department of Pediatrics
- Record Identifier
- 9984353772902771
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