吸入麻醉药对猪脑氧代谢及机体氧供需平衡的影响

目的 观察不同浓度吸入麻醉药对脑氧代谢及机体氧供需平衡的影响。方法 健康杂种小型猪15例随机分为异氟醚组、地氟醚组和七氟醚组，持续监测心排量，颈动脉血流，动脉、外周静脉及颈静脉血气分析，计算不同浓度吸入麻醉药下的脑氧代谢率(CMRO2，)、脑氧供(CD02)、脑氧耗(Cvo2)和机体氧供(D02)、氧耗(v02)。结果 三组CMRO2随吸入药浓度增加而呈下降趋势。在0．5—1．0肺泡气最低有效浓度(MAC)时，三组脑血流(CBF)随浓度增加而增加；吸入1．5MAC时，脑血流量下降至基础水平。在1．0MAC时，CDO2较用药前明显增加，脑氧摄取率(COER)明显降低；随吸入浓度增加，CDO2呈下降趋势，而COER呈上升趋势。DO2随吸入浓度增加而下降，1．0、1．5MAC时DO2下降尤为显著；1．5MAC时三组VO2均明显下降。结论 地氟醚、七氟醚在低浓度时均明显增加CBF，降低CM—RO2，随吸入浓度增加，对机体循环血流动力学和氧供需的影响大于脑循环。异氟醚在小于1．0MAC时，对脑氧代谢和脑血流及体循环血压的影响小于地氟醚和七氟醚，随着吸入浓度的增加，对心、脑功能产生明显的影响。

Effects of Inhaled Anesthetics with Different Concentration on Oxygenic Metabolism in Porcine Brain and System

[Objective To observe the effect of inhaled anesthetics with different concentrations on oxygen metabolism of the brain and body. Methods Fifteen pigs were randomly divided into three groups: isoflurane group, desflurene group and sevoflurane group. The cardiac output, carotid flow and blood gas analysis of artery, peripheral vein and jugular vein continuously were monitored, and cerebral metabolic rate of oxygen ( CMRO2 ) , cerebral oxygen delivery ( CDO2 ) , cerebral oxygen consumption ( CVO2) , oxygen delivery ( DO2) and oxygen consumption ( VO2) at different concentrations were calculated. Results Three groups the CMRO2 tended to decline with increase of inhaled concentration. The cerebral blood flow (CBF) increased with increase of concentration between 0. 5-1.0MAC but fell to the basic level at 1.5MAC. The CDO2 increased and cerebral oxygen uptake rate (GOER) decreased significantly compared with the previous levels at 1.0MAC , the CDO2 tended to lower down while GOER conversely rose up with increase of inhaled concentration. DO2 decreased with increase of inhalant concentration. VO2 decreased obviously at 1.5MAC in all groups. Conclusion Both desflurane and sevoflurane increased CBF and decreased CMRO2 obviously at lower concentrations. With increased concentration, they might have more intensive effect on circulative hemodynamics and oxygen metabolism of the body than those of the brain. Isoflurane has little influence on oxygen metabolism and blood flow of cerebral and systemic hemodynamics when the concentration less than l.0MAC. With increase of inhalant concentration,and mayproduce marked influence on the function of the brain and the heart.