Hypothermia Improves Oral and Gastric Mucosal Microvascular Oxygenation during Hemorrhagic Shock in Dogs

Abstract

Hypothermia is known to improve tissue function in different organs during physiological and pathological conditions. The aim of this study was to evaluate the effects of hypothermia on oral and gastric mucosal microvascular oxygenation (μHbO2) and perfusion (μflow) under physiological and hemorrhagic conditions. Five dogs were repeatedly anesthetized. All animals underwent each experimental protocol (randomized cross-over design): hypothermia (34°C), hypothermia during hemorrhage, normothermia, and normothermia during hemorrhage. Microcirculatory and hemodynamic variables were recorded. Systemic (DO2) and oral mucosal (μDO2) oxygen delivery were calculated. Hypothermia increased oralμHbO2with no effect on gastricμHbO2. Hemorrhage reduced oral and gastricμHbO2during normothermia (−36 ± 4% and −27 ± 7%); however, this effect was attenuated during additional hypothermia (−15 ± 5% and −11 ± 5%). The improvedμHbO2might be based on an attenuated reduction inμflow during hemorrhage and additional hypothermia (−51 ± 21 aU) compared to hemorrhage and normothermia (−106 ± 19 aU).μDO2was accordingly attenuated under hypothermia during hemorrhage whereas DO2did not change. Thus, in this study hypothermia alone improves oralμHbO2and attenuates the effects of hemorrhage on oral and gastricμHbO2. This effect seems to be mediated by an increasedμDO2on the basis of increasedμflow.