Preoperative Ultrasound-Guided Inferior Vena Cava Collapsibility Index as a Guide to Predict Hypotension Following Spinal Anesthesia

Abstract

Objective: Post-spinal hypotension is a commonly encountered complication following spinal anesthesia. However, there is a dearth of a concrete tool to predict spinal-induced hypotension (SIH) and differentiate the cohort of patients requiring fluid boluses versus vasopressors to correct it. Thus, we aimed to determine the prognostic efficacy of ultrasonographic assessment of inferior vena caval collapsibility index (IVC-CI) to predict hypotension following spinal anesthesia and compare the requirements of crystalloids and Mephentermine among patients with IVC-Collapsibility Index >50% and <50%. Methods: This observational study was conducted in the Department of Anesthesiology, Government Medical College, Kottayam. Preoperative IVC Ultrasonography was performed in 74 patients of ASA Grade 1–2 scheduled for elective surgery under spinal anesthesia and their IVC-CI was determined. Spinal anesthesia procedure protocol was standardized. Mean arterial pressure, intravenous fluids, and mephentermine requirements were documented in both IVC-CI groups. Results: There was no significant difference in the demographics or pre-operative vital signs between the two groups. Significant hypotension was seen in 51.4% of patients. 97% of patients with IVC-CI>50% had significant hypotension, p=0.000. IVCCI>50% is 97.2% specific and 84.2% sensitive in predicting SIH with a positive predictive value of 96.97% and negative predictive value of 85.37%. Significantly, high requirement of intravenous fluids and mephentermine was noted among IVC-CI>50% group, p=0.000 and 0.026, respectively. Conclusion: USG-guided IVC-CI is an easy to perform, non-invasive, time-efficient, and readily available technique to assess fluid responsiveness. Patients with IVC-CI>50% are more likely to develop SIH. Furthermore, the requirement of vasopressors and IV fluids increases with IVC-CI>50%. USG-guided IVC-CI is a reliable predictor of SIH.