Assessment of role of inferior vena cava collapsibility index and variations in carotid artery peak systolic velocity in prediction of post-spinal anaesthesia hypotension in spontaneously breathing patients: An observational study.

Background and Aims: Post-spinal anaesthesia hypotension (PSH) is common and can lead to significant morbidity and mortality. The inferior vena cava collapsibility index (IVCCI) and carotid artery peak systolic velocity variations (CAPVV) are two widely used parameters for assessing the volume status of critically ill patients which have also been investigated as predictors of PSH and hypotension after induction of general anaesthesia. In this study, we evaluated the diagnostic accuracy of IVCCI and CAPVV as predictors of PSH. Methods: A total of 50 patients aged between 18 and 65 years undergoing elective lower abdominal surgeries under spinal anaesthesia were included. The IVCCI and CAPVV were measured using ultrasound pre-operatively. After administering spinal anaesthesia, haemodynamic data were collected till 15 min. Our primary objective was to evaluate the role of IVCCI and CAPVV to predict PSH. The secondary objectives were to compare the predictive efficacy of these two parameters and to detect other parameters for predicting PSH. We constructed the receiver operator characteristic (ROC) curves for IVCCI and CAPVV and obtained the best cut-off values. Results: The PSH occurred in 34% of the patients. IVCCI >21.15 could predict PSH with 58.8% sensitivity and 69.7% specificity. CAPVV >18.33 predicted PSH with 70.6% sensitivity and 54.6% specificity and IVC max/IVCCI >60 could predict PSH with 58.8% sensitivity and 54.5% specificity. A composite model comprising IVCmax (maximum IVC diameter), CAPVV, and baseline mean blood pressure was able to predict PSH. Conclusion: Both IVCCI and CAPVV have poor diagnostic accuracy in predicting PSH in adult patients undergoing elective infra-umbilical surgery.