Pre-anesthesia ultrasound monitoring of subclavian vein diameter changes induced by modified passive leg raising can predict the occurrence of hypotension after general anesthesia: a prospective observational study

BACKGROUND: Perioperative hypotension increases postoperative complication rates and prolongs postoperative recovery time. Whether Passive Leg Raising test (PLR) and Subclavian Vein Diameter (DSCV) can effectively predict post-anesthesia hypotension remains to be tested. This study aimed to identify specific predictors of General Anesthesia (GA)induced hypotension by measuring DSCV in the supine versus PLR position. METHODS: A total of 110 patients who underwent elective gynecological laparoscopic surgery under general anesthesia, were enrolled in this study. Before anesthesia, DSCV and theCollapsibility Index of DSCV(DSCV-CI) were measured by ultrasound, and the difference in maximal values of DSCV between supine and PLR positions was calculated, expressed as ΔDSCV. Hypotension was defined as Mean Blood Pressure (MBP) below 60mmhg or more than 30% below the baseline. Patients were divided into two groups according to the presence (Group H) or absence (Group N) of postanesthesia hypotension. The area under the receiver operating characteristic curve (ROC) and logistic regression analyses were used to evaluate the predictability of DSCV and other parameters for predicting preincision hypotension. RESULTS: Three patients were excluded due to unclear ultrasound scans, resulting in a total of 107 patients studied. Twenty-seven (25.2%) patients experienced hypotension. Area under the ROC curve of ΔDSCV was 0.75 (P < 0.001) with 95% confidence interval (0.63–0.87), while DSCV and DSCV-CI were less than 0.7. The odds ratio (OR)of ΔDSCV was 1.18 (P < 0.001, 95%CI 1.09–1.27) for predicting the development of hypotension. ΔDSCV is predictive of hypotension following induction of general anesthesia. CONCLUSIONS: ΔDSCV has predictive value for hypotension after general anesthesia. TRIAL REGISTRATION: The trial was registered in the Chinese Clinical Trial Registry on 04/10/2021.