Ultrasound Measurement of Inferior Vena Cava Collapsibility as a Tool to Predict Propofol-Induced Hypotension

BACKGROUND: Hypotension is common under anesthesia and can cause organ underperfusion and ischemia, especially during induction. This could be because of the cardiovascular depressant and vasodilatory effects of anesthetic agents, as well as lack of surgical stimulation. AIM OF STUDY: The aim was to evaluate the utility of preinduction inferior vena cava (IVC) measurement to predict significant hypotension after induction of anesthesia with propofol. SETTINGS AND DESIGN: This was a prospective, open-label study conducted in a tertiary care institute. SUBJECTS AND METHODS: This study was conducted on 50 patients undergoing general anesthesia. Ultrasound machine (Mindray® M7) was used to visualize IVC. The measurements taken were maximum diameter of IVC (IVC(max)) and minimum diameter of IVC (IVC(min)). IVC collapsibility index (IVC-CI) was calculated as (IVC(max) − IVC(min))/IVC(max) and was expressed as a ratio. STATISTICAL TESTS USED: Receiver operating characteristic (ROC) curve analysis and Chi-square test were used for statistical tests. RESULTS: The relation between significant hypotension and IVC-CI was evaluated using ROC curve analysis. We found the area under curve to be 0.959 and a cutoff of 0.43 (43% collapsibility). The association of significant hypotension with IVC-CI of >43% was calculated and found to be statistically significant (P < 0.001). The sensitivity of IVC CI of >43% in predicting development of significant hypotension was 86.67% and the specificity was 94.29%. It had very high negative and positive predictive values (94.29% and 86.67%, respectively) with an accuracy of 92%. CONCLUSION: Patients with an IVC collapsibility of more than 43%, as assessed by ultrasonography, are more likely to develop significant hypotension after induction with propofol.