The effects of early prone position on inflammatory response and mortality in porcine model of massive gastric aspiration

Abstract

Background Aspiration of gastric contents, a common complication in critically ill patient, is a common cause of acute lung injury (ALI)/acute respiratory distress syndrome (ARDS), which leads high mortality.

Objectives To test the effects of early prone position on mortality in porcine after massive gastric aspiration and explore the possible mechanism.

Methods Twelve female healthy pigs were anesthetized and mechanically ventilated. Massive gastric aspiration model was created by ejecting 7ml/kg gastric contents fluids (pH=1 hydrochloric acid solution to dilute 40mg/ml gastric particles). They were randomly divided into the supine position group(SP)or prone position group(PP). Oxygenation (PaO₂/FiO₂), intrapulmonary shunt index (Q_s/Q_t), and the number of death were observed hourly for a total of 6 hours after aspiration. Interleukin-6 was measured in serum, and immunohistochemistry was performed to study interleukin-6 expression in the lung tissue.

Results All 6 animals in SP group died within 6 hours after aspiration, while only one died in PP group (χ²=7.071, P<0.01). The PaO₂/FiO₂ level in PP group was significantly higher than that in SP group (P<0.01), and the trend of lower Qs/Qt was found in PP group than that in SP group (P<0.05). The serum level of interleukin-6 in PP group was significantly lower than that in SP group (P<0.01), and interleukin-6 expression decreased in PP group compared with SP group (P<0.05).

Conclusions Early Prone position can improve oxygenation and intrapulmonary shunt, reduce inflammatory response and mortality rate in massive gastric aspiration.

Key words Prone position; Gastric aspiration; Mortality; Interleukin-6.