Effects of environmental hypothermia on hemodynamics and oxygen metabolism in unanesthetized swine model of hemorrhagic shock

Abstract

Objective To investigate the effects of environmental hypothermia on hemodynamics and oxygen metabolism in unanesthetized swine model of hemorrhagic shock.Methods A total of 16 Bama pigs provided by animal experiment centre of the General Hospital of Shenyang Military Command were randomized into two groups ( n =8,each):ambient temperature (A) and hypothermia ( H ).Venous blood (30 mL/kg) was continously withdrawn over 15 minutes to establish hemorrhagic shock model.Core temperature,heart rate,mean arterial pressure,central venous pressure,cardiac output,saturation of mixed venous blood and blood gas analysis were recorded at the baseline and different hemorrhagic shock time.DO2I and VO2I,and the O2 extraction ratio (O2ER) were calculated.Results Core body temperature in group A decreased slightly after hemorrhagic shock model had established and environmental hypothermia resulted in more reduction in core body temperature.The mortality rate was significantly higher in group H (50％) than in group A (0％) (P ＜0.05).DO2I and VO2I decreased significantly after hemorrhage.No difference was found in hemodynamics,DO2I and VO2I between group A and group H,but the difference of pH,lactic acid and O2ER were significant between the two groups (P ＜ 0.05 ).conclusions Environmental hypothermia aggravated the disorder of oxygen metabolism after hemorrhagic shock,which was associated with poor prognosis. Key words: Hemorrhagic shock; Environmental hypothermia; Hemodynamics; Oxygen metabolism; Anesthesia; Swine; Core temperature; Prognosis