BACKGROUND: Hypotension is a common side effect of propofol induction, and when severe, it is associated with adverse outcomes. Ultrasonography of the inferior vena cava (IVC) is a reliable indicator of the intravascular volume. This study investigated whether preoperative IVC ultrasound measurements could predict hypotension after propofol induction in patients undergoing colonoscopies. METHODS: Sixty-two adult patients with American Society of Anesthesiologists physical status (ASA) I-II scheduled for colonoscopy after propofol induction were recruited. The Ultrasound Maximum IVC diameter (dIVCmax), minimum IVC diameter (dIVCmin), and collapsibility index (IVC-CI) were assessed in all patients before propofol induction. Mean blood pressure (MBP) was recorded before induction. Propofol was injected intravenously after ultrasound measurements. MBP was recorded 1, 3, 5, and 10 min after propofol induction. The receiver operating characteristic (ROC) curve of IVC-CI was compared with that of patients who developed hypotension after propofol induction. RESULTS: Sixty-two patients completed the study, and their data were considered for statistical analysis. After induction,30 patients developed hypotension. The area under the curve (95% confidence interval) was 0.72 (0.595 to 0.849) for IVC-CI. The optimal IVC-CI cutoff value was 38.25%, with a sensitivity of 56.7% and specificity of 71.9%. IVC-CI before induction strongly correlated with the maximum percentage of MBP drop after propofol induction. (regression coefficient = 0.33, P = 0.008), respectively. CONCLUSION: Pre-induction IVC-CI >
38.25% is a non-invasive predictor of propofol-induced hypotension in patients undergoing colonoscopy and is strongly correlated with MBP drop. TRIAL REGISTRATION: This clinical trial was approved by the Ethics Committee of The Affiliated Lianyungang Hospital of Xuzhou Medical University (YJ-20190529001). All the study procedures were performed in accordance with the ethical standards of the Helsinki Declaration of 2013.