Regional hypothermia improves gastric microcirculatory oxygenation during hemorrhage in dogs

Mild systemic hypothermia increases gastric mucosal oxygenation (μHbO(2)) during hemorrhagic shock in dogs. In the context of critical blood loss hypothermia might be fatal due to adverse side effects. Selective regional hypothermia might overcome these limitations. The aim of our study was to analyze the effects of regional gastric and oral mucosal hypothermia on μHbO(2) and perfusion (μflow). In a cross-over study six anesthetized dogs were subjected to local oral and gastric mucosal hypothermia (34°C), or maintenance of local normothermia during normovolemia and hemorrhage (-20% blood volume). Macro- and microcirculatory variables were recorded continuously. During normovolemia, local hypothermia increased gastric microcirculatory flow (μflow) without affecting oxygenation (μHbO(2)) or oral microcirculation. During mild hemorrhagic shock gastric μHbO(2) decreased from 72±2% to 38±3% in the normothermic group. This was attenuated by local hypothermia, where μHbO(2) was reduced from 74±3% to 52±4%. Local perfusion, oral microcirculation and macrocirculatory variables were not affected. Selective local hypothermia improves gastric μHbO(2) during hemorrhagic shock without relevant side effects. In contrast to systemic hypothermia, regional mucosal hypothermia did not affect perfusion and oxygen supply during hemorrhage. Thus, the increased μHbO(2) during local hypothermia rather indicates reduced mucosal oxygen demand.