脉搏灌注变异指数预测俯卧位引起的 心排血量下降的研究

Application of pleth variability index in predicting reduction in cardiac output induced by prone position

摘要:

目的 探讨脉搏灌注变异指数（PVI）在患者从平卧位改为俯卧位后引起的心排血量（CO）下降 中的预测作用。方法 选取全身麻醉下行腰椎手术的患者40 例，ASA Ⅰ～Ⅲ级，年龄35 ～ 62 岁。全身麻醉 后连接Vigileo 系统监测每搏量变异度（SVV）、CO，同步使用Massion Radical 7 系统监测PVI、脉搏灌注指数 （PI）。分别记录平卧位及俯卧位时心率（HR）、平均动脉压（MAP）、CO、心指数（CI）、每搏量指数（SVI）、 SVV、PI、PVI 的数值，比较两个时间点各血流动力学数据的差异。计算俯卧位前后心排血量差异（△ CO）， [ △ CO=（俯卧位前CO- 俯卧位后CO）/ 俯卧位前CO×100%]，△ CO ≤ 15% 为容量负荷足以减轻俯卧位 后CO 的下降，绘制各血流动力学指标的受试者工作特征性（ROC）曲线，计算其曲线下面积及诊断阈值， 并计算俯卧位前后SVV 与PVI 的相关性。结果 SVV 与PVI 的ROC 曲线下面积分别为0.946 和0.844 ；SVV 的敏感性为91.3%，特异性为88.2%，诊断阈值为12.5% ；PVI 的敏感性为87.0%，特异性为76.5%，诊断阈值 为14.5%。俯卧位前后PVI 与SVV 均呈线性正相关，俯卧位前相关系数（r = 0.712，P < 0.05）高于俯卧位后 （r = 0.440，P < 0.05）。结论 PVI 能通过判断仰卧位患者的容量负荷状态，预测俯卧位后引起的CO 下降程度。

Abstract:

Objective To evaluate the use of pleth variability index (PVI) in predicting the decrease in cardiac output (CO) from supine position to prone position. Methods Forty patients of ASA I-III aged 35-62 years undergoing elective lumbar spine surgery were enrolled. After induction of general anesthesia, CO and stroke volume variability (SVV) were monitored with Vigileo system, while PVI and perfusion index (PI) were monitored with Massion Radical 7 system. Heart rate (HR), mean arterial pressure (MAP), CO, SVV, cardiac index (CI), stroke volume index (SVI), PI and PVI were recorded both at supine position and prone position. The difference of cardiac output ( △ CO) before and after prone position was calculated with the following equation: △ CO = [CO (supine)- CO (prone)] / CO (supine) × 100%. △ CO of 15% was regarded as the threshold that the patient's cardiac preload is sufficient enough to help to alleviate the decline in cardiac output when turned prone. The receiver operatorcharacteristic (ROC) curves of the hemodynamic indicators were drawn to decide the accuracy of its prediction on the cardiac preload and the diagnostic threshold. And the correlation between SVV and PVI was also analyzed both before and after prone position. Results ROC curves manifested that the area under the curves of SVV and PVI was 0.946 and 0.844 respectively, larger than those of other hemodynamic indexes. The sensitivity, specificity and diagnostic threshold of SVV were 91.3%, 88.2% and 12.5% respectively; whereas the sensitivity, specificity and diagnostic threshold of PVI were 87.0%, 76.5% and 14.5 % respectively. There was a linear relationship between PVI and SVV both in supine position and prone position, and the correlation coefficient in supine position (r = 0.712, P < 0.05) was higher than that in prone position (r = 0.440, P < 0.05). Conclusions Pleth variability index helps to predict the decline of cardiac output due to the prone position through calculating the patients' cardiac preload in supine position.