目的 探讨微容量负荷试验对老年骨科患者腰麻后低血压的预测价值。 方法 严格按照入选和排除标准筛选出行髋关节或膝关节置换的老年患者72例，均为安排蛛网膜下腔阻滞麻醉的择期手术患者。依据研究对象接受单次细针腰麻后于仰卧位状态下15 min内血压改变进行分组，参考既往文献低血压定义标准分为血压降低组（H组）和血压正常组（N组）共两组。实施细针腰麻前进行微容量负荷试验，采用无创心排血量监测仪测量每搏量指数变异度（variation of stroke volume index，ΔSVI）并记录血压及心率等循环数据的基线值。采用多因素logistic回归分析接受腰麻下行骨科关节置换手术的老年患者低血压的影响因素，绘制ΔSVI的受试者工作特征（ROC）曲线并计算曲线下面积（AUC），评价ΔSVI的预测价值。 结果 腰麻后有29例（40.27%）患者发生低血压。与N组相比，仰卧位状态下15 min内发生低血压的H组患者年龄更大，ASAⅢ级、合并高血压比例更高。分析结果显示ΔSVI是老年患者腰麻后低血压的独立影响因素。ΔSVI在≥ 0.805%时，预测腰麻后低血压的敏感度为 82.8%，特异度为81.4%，曲线下面积为0.868。ΔSVI与SBP最大降低幅度呈正相关（r = 0.562，P < 0.01）。 结论 微容量负荷试验是一种有效预测老年骨科患者腰麻后低血压的方法。

Objective To investigate the predictive value of the mini?fluid challenge test in elderly orthopedic patients for post?spinal anesthesia hypotension. Methods Seventy?two elderly patients who underwent elective hip or knee replacement surgery were rigorously screened according to predefined inclusion and exclusion criteria. All patients were scheduled for subarachnoid block anesthesia. Subjects were grouped based on changes in blood pressure within 15 minutes of assuming a supine position following single?shot lumbar anesthesia. According to previously established definitions of hypotension， they were categorized into either the hypotension group （H group） or the normal blood pressure group （N group）. Prior to spinal anesthesia， a mini?fluid challenge test was conducted using noninvasive cardiac output monitoring to measure the change in stroke volume index （ΔSVI）， and baseline circulatory data were recorded. Multivariate logistic regression analysis was employed to identify factors influencing outcomes in elderly patients undergoing orthopedic joint replacement surgery. Receiver operating characteristic （ROC） curves for ΔSVI were constructed， and the area under the curve （AUC） was calculated to evaluate its predictive performance. Results After spinal anesthesia， 29 patients （40.27%） experienced hypotension. Compared with Group N， patients in Group H who experienced hypotension within 15 minutes while in a supine position were significantly older， had a higher proportion of ASA grade III， and a higher prevalence of hypertension （P < 0.05）. The analysis results indicated that ΔSVI was an independent influencing factor for post?lumbar anesthesia hypotension in elderly patients. ΔSVI demonstrated a sensitivity of 82.8% and a specificity of 81.4% in predicting post?spinal anesthesia hypotension （PSAH） at a cut?off value of 0.805 or greater. There was a moderate positive linear correlation between the maximum decrease in systolic blood pressure （SBP） and ΔSVI （r = 0.562， P < 0.01）. Conclusion The mini?fluid challenge test is an effective method for predicting hypotension in elderly orthopedic patients following spinal anesthesia.