剖宫产术中左右趾灌注指数预测腰麻后低血压的不同作用
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Differential Roles of the Right and Left Toe Perfusion Index in Predicting the Incidence of Postspinal Hypotension During Cesarean Delivery
背景与目的
妊娠子宫对下腔静脉的压迫和腰麻对交感神经的阻滞引起血管扩张是剖宫产术中腰麻后低血压的主要机制。手指灌注指数（PI）可通过反映基础血管张力从而预测腰麻后低血压，但不能反映下腔静脉的受压情况。本研究主要探讨腰麻前后足趾PI的变化是否可以预测腰麻后低血压的发生，以及是否可以反映妊娠子宫对下腔静脉的压迫情况。
方 法
本研究共纳入100名行择期剖宫产的产妇。腰麻后，将2只监测PI探头分别放在产妇的左右第二脚趾上，连续监测脚趾PI和灌注变异指数(PVI)，血压测量间隔从每3分钟改为每1分钟一次，直到胎儿娩出，比较左右脚趾PIs数据。
结 果
左脚趾PI的ROC曲线下面积为0.81(95％CI：0.71～0.88)，右脚趾PI的ROC曲线下面积为0.76(95％CI：0.66～0.84)。腰麻后，低血压状态下脚趾PIs并不会发生变化，但未发生低血压的产妇PIs会显著增加。
结 论
本研究表明剖宫产术期间基础脚趾PIs与低血压的发生呈反向变化。腰麻后持续PIs持续监测有助于预测低血压的发生及反映下腔静脉受压情况。
原始文献摘要
Xu Z, Xu T, Zhao P, et al. Differential Roles of the Right and Left Toe Perfusion Index in Predicting the Incidence of Postspinal Hypotension During Cesarean Delivery[J]. Anesthesia & Analgesia, 2017.
BACKGROUND: Aortocaval compression by the gravid uterus, low baseline vasomotor tone, and spinal anesthesia-related sympathetic blockade contribute to spinal anesthesia-induced hypotension during cesarean delivery. The finger perfusion index (PI) can predict spinal hypotension by reflecting baseline vasomotor tone, but cannot directly reflect aortocaval compression by the gravid uterus. This study aimed to examine whether baseline toe PIs predict the incidence of maternal hypotension and reflect aortocaval compression by the gravid uterus during cesarean delivery under spinal anesthesia.
METHODS: One hundred parturients undergoing elective cesarean delivery were enrolled. The relationship between baseline toe PI and the incidence of hypotension after induction of spinal anesthesia was quantified using area under the receiver operator curves, and results compared for the right and left toe PIs.
RESULTS: The area under the receiver operator curves for left and right toe baseline PIs were 0.81 (95% confidence interval, 0.71–0.88) and 0.76 (95% confidence interval, 0.66–0.84), respectively. After induction of spinal anesthesia, the toe PIs did not change in parturients with hypotension, but increased significantly among those who did not develop hypotension.
CONCLUSIONS: Our study demonstrated that baseline toe PIs were inversely associated with the incidence of postspinal hypotension during cesarean delivery. Continuous monitoring of toe PIs during induction of spinal anesthesia might help to predict the development of postspinal hypotension and reflect the aortocaval compression by the gravid uterus.
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