俯卧位呼吸末正压对每搏量变异度、脉搏压变异度和脉搏灌注变异指数预测容量准确性及阈值的影响

目的观察俯卧位应用不同呼气末正压条件下对每搏量变异度、脉搏压变异度及脉搏灌注变异指数预测容量状态的准确性及诊断阈值的影响。方法选择在全麻下俯卧位行颈椎或腰椎手术患者60例,全麻后连续监测每搏量变异度(SVV)、脉搏压变异度(PPV)、脉搏灌注变异指数(PVI)等血流动力学指标,在俯卧位体位下分别加以0、5、10、15 mm Hg的呼气末正压(PEEP),记录每个PEEP时点的各血流动力学指标数值,后以7 ml/kg进行补液试验后,再分别加以0、5、10、15 mm Hg的PEEP值后记录输液后各血流动力学指标数值。然后以输液前后每搏量变异指数的差值(ΔSVI)将患者分为两组,即有反应组(ΔSVI≥15%)和无反应组(ΔSVI<15%)组,分别绘制SVV、PPV和PVI判断扩容效应的受试者工作特征性(ROC)曲线,确定俯卧位时在不同PEEP条件下对SVV、PPV和PVI预测容量状况的准确性、诊断阈值及其相关性。结果与平卧位相比较,俯卧位条件下SVV、PPV、PVI均增大(P<0.05),平均动脉压降低(P<0.05),心率、每搏量、每搏量指数、心输出量、心指数差异无统计学意义(P>0.05)。俯卧位时,在PEEP=0、5、10、15 mm Hg条件下,SVV判断扩容有效的ROC曲线下面积分别为0.864、0.759、0.718、0.521,PPV判断扩容有效的ROC曲线下面积分别为0.873、0.792、0.705、0.505,PVI判断扩容有效的ROC曲线下面积分别为0.851、0.765、0.709、0.512。当PEEP=0 mm Hg时,SVV、PPV、PVI诊断阈值分别为10.5、11.5、13.5;当PEEP=5 mm Hg时,SVV、PPV、PVI诊断阈值分别为11.5、13.5、14.5;当PEEP=10 mm Hg时,SVV、PPV、PVI诊断阈值分别为13.5、14.5、16.5。俯卧位时在不同PEEP条件下SVV、PPV、PVI变化分别与PEEP值变化呈正相关(r分别为0.424、0.561、0.553,P<0.01)。结论 SVV、PPV和PVI在PEEP≤10 mm Hg时可以准确预测俯卧位时应用全麻机械通气患者的容量状况,三者预测容量状况的准确性相似,诊断阈值随PEEP值增大而增大,诊断的准确性随PEEP值增大而下降;在PEEP=15 mm Hg时,SVV、PPV和PVI不能准确预测俯卧位时应用全麻机械通气患者的容量状况。

Effects of Stroke Volume Variation,Pulse Pressure Variation,and Pleth Variability Index in Predicting Fluid Responsiveness during Different Positive End Expiratory Pressure in Prone Position

Objective To investigate the effects of different positive end expiratory pressures(PEEP)on functional hemodynamic parameters in patients lying in prone position during operation under general anesthesia.Methods Totally 60 patients undergoing cervical vertebra operation or lumbar vertebra operation were studied.All patients were also monitored with Vigileo／FloTrac system.The functional hemodynamic parameters including stroke volume variation(SVV),pulse pressure variation(PPV),and pleth variability index(PVI)under PEEP levels of 0 mmHg,5 mmHg,10 mmHg,and 15 mmHg were recorded before and after volume expansion(hydroxyethyl starch 6%,7 ml/kg).Fluid responsiveness was defined as an increase in stroke volume index(SVI)≥15%(△SVI≥15%).Responders were defined as patients demonstrating an increase in SVI≥15% after intravascular volume expansion and non-responders as patients whose SVI changed＜15%.Receiver operating characteristic(ROC)curves were generated for SVV,PPV,and PVI under different PEEP levels to determine their diagnosis accuracies and thresholds and their potential correlations.Results In the prone position,SVV,PPV,and PVI were significantly higher compared to those in the supine position(P＜0.05)and the mean arterial pressure significantly decreased(P＜0.05);however,the changes of heart rate,stroke volume,SVI,cardiac output,and cardiac index showed no significant difference(P＞0.05).In the prone position,along with the elevation of PEEP(0 mmHg,5 mmHg,10 mmHg,and 15 mmHg),the areas under the ROC curves of SVV were 0.864,0.759,0.718,and 0.521,the area under the ROC of PPV were 0.873,0.792,0.705,and 0.505,and the area under the ROC of PVI were 0.851,0.765,0.709,and 0.512.Under PEEP=0 mmHg,the diagnostic thresholds of SVV,PPV,and PVI were 10.5,11.5,and 13.5.Under PEEP=5 mmHg,the diagnostic thresholds of SVV,PPV,and PVI were 11.5,13.5,and 14.5.Under PEEP=10 mmHg,the diagnostic thresholds of SVV,PPV,and PVI were 13.5,14.5,and 16.5.In the prone position,there was a significant correlation between SVV,PPV,PVI,and PEEP. Conclusions SVV,PPV and PVI can predict fluid responsiveness similarly under the PEEP levels of 0,5, and 10 mmHg.Their diagnostic thresholds increases with the PEEP and the diagnostic accuracies decrease with the PEEP.However,under the PEEP level of 15 mmHg,SVV,PPV,and PVI can not predict fluid responsiveness accurately.