Estimating the usefulness of inferior vena cava collapsibility index and caval aorta index to predict hypotension after spinal anaesthesia in adult patients undergoing elective surgery in a tertiary care hospital

Post-spinal anaesthesia hypotension (PSAH) can occur in 25–75% of patients. The preload or volume status of a patient is an important contributor to PSAH, and coloading with fluids is advocated to prevent PSAH. Instead of blind volume loading, prediction of volume status using inferior vena cava (IVC) collapsibility index (IVCCI) and caval aorta index (IVC:Ao index) may be used to guide fluid administration. In our study, we used ultrasound in the immediate pre-operative period to calculate IVCCI and IVC:Ao index in patients scheduled for elective surgery in the supine position, under spinal anaesthesia. Spinal anaesthesia was given in the lateral position with 0.5% hyperbaric bupivacaine. Patients were placed supine thereafter, sensory blockade level was ascertained, and blood pressure (BP) was measured every 2 min for 30 min. Episodes of hypotension were treated with fluids or vasopressors as per the discretion of the treating anaesthesiologist. In the study, 73 patients were screened, out of which 69 were included. Totally, 23 participants out of 69 developed PSAH. The receiver operating characteristic (ROC) curve was made and the area under the curve analysis was done on our collected data. We found that IVC:Ao index has better sensitivity (0.696 for IVC:Ao index ≤0.810) and specificity (0.717 for IVC:Ao index ≤0.810) than IVCCI (sensitivity 0.522 and specificity 0.630 for IVCCI ≥33.32%) to predict PSAH. IVC:Ao index is a better predictor of PSAH than IVCCI. Thus, it may be used to predict volume status and guide in coloading with fluids during spinal anaesthesia.