Abstract
To compare the effectiveness of mechanical ventilation of supine versus prone position in hydrochloric acid (HCl)-induced lung dysfunction. Twenty, adult, male, Wistar-EPM-1 rats were anesthetized and randomly grouped (n=5 animals per group) as follows: CS-MV (mechanical ventilation in supine position); CP-MV (mechanical ventilation in prone position); bilateral instillation of HCl and mechanical ventilation in supine position (HCl+S); and bilateral instillation of HCl and mechanical ventilation in prone position (HCl+P). All groups were ventilated for 180 minutes. The blood partial pressures of oxygen and carbon dioxide were measured in the time points 0 (zero; 10 minutes before lung injury for stabilization), and at the end of times acid injury, 60, 120 and 180 minutes of mechanical ventilation. At the end of experiment the animals were euthanized, and bronchoalveolar lavages (BALs) were taken to determine the contents of total proteins, inflammatory mediators, and lungs wet-to-dry ratios. In the HCl+P group the partial pressure of oxygen increased when compared with HCl+S (128.0+/-2.9 mmHg and 111.0+/-6.7 mmHg, respectively) within 60 minutes. TNF-alpha levels in BAL do not differ significantly in the HCl+P group (516.0+/-5.9 pg/mL), and the HCl+S (513.0+/-10.6 pg/mL). The use of prone position improved oxygenation, but did not reduce TNF-alpha in BAL upon lung dysfunction induced by HCl.
Highlights
Mechanical ventilation (MV)Gastric acid aspiration is a common etiology of acute lung injury (ALI) and is initially characterized by a chemical “burn” of the pulmonary epithelium, with a subsequent influx of extracellular fluid into the alveolar space that leads to pulmonary edema
After 10 min connected in the ventilator for stabilization, the lung injury was performed using a 0.1 N hydrochloric acid (HCl) solution (2 mL/kg) instilled in the endotracheal tube in the supine position with the rat disconnected from the ventilator, the aspiration of HCl solution was performed in an inverted Trendelenburg position
Differences could be observed after induced lung injury in groups HCl and mechanical ventilation in supine position (HCl+S) and HCl and mechanical ventilation in prone position (HCl+P) when compared with their respective controls (Table 1, Figures 1, 2 and 3)
Summary
Mechanical ventilation (MV)Gastric acid aspiration is a common etiology of acute lung injury (ALI) and is initially characterized by a chemical “burn” of the pulmonary epithelium, with a subsequent influx of extracellular fluid into the alveolar space that leads to pulmonary edema. Effects of prone and supine position on oxygenation and inflammatory mediator in a hydrochloric acid-induced lung dysfunction in rats The use of prone ventilation has been shown to improve aeration and decrease alveolar shunt in an animal model[9]. The purpose of this study was to test the hypothesis whether mechanical ventilation with prone position improves arterial oxygenation and decreases local inflammatory dysfunction on an experimental model of ALI.
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