Association of Pre-Spinal Shock Indices and Right Internal Jugular Vein Collapsibility Index with Post-Spinal Hypotension During Cesarean Delivery: A Prospective Observational Study.

Background and Objectives: Postspinal hypotension (PSH) remains a common complication of cesarean delivery under spinal anesthesia. Simple prespinal predictors may assist in identifying patients at increased risk. This study evaluated the associations of shock index (SI), modified shock index (MSI), diastolic shock index (DSI), and right internal jugular vein collapsibility index (RJV-CI) with postspinal hypotension (PSH). Materials and Methods: This prospective observational study included term parturients undergoing elective cesarean delivery under spinal anesthesia. Prespinal SI, MSI, DSI, and RJV-CI were measured before intrathecal injection. PSH was defined as systolic arterial pressure <90 mmHg or a reduction of ≥30% from baseline within 15 min after intrathecal injection. Receiver operating characteristic (ROC) analyses were performed for individual predictors. Three logistic regression models combining RJV-CI with SI, MSI, or DSI were evaluated using bootstrap internal validation. Results: Of 80 enrolled patients, 76 were included in the final analysis; 36 (47.4%) developed PSH. SI, MSI, DSI, and RJV-CI were significantly higher in the PSH group than in the non-PSH group. The areas under the ROC curve (AUCs) were 0.757 for SI, 0.747 for MSI, 0.693 for DSI, and 0.709 for RJV-CI. In multivariable models, RJV-CI remained significantly associated with PSH after adjustment for the respective shock index. The model combining RJV-CI and SI showed the highest apparent AUC (0.790; 95% confidence interval, 0.688-0.886) and an optimism-corrected AUC of 0.775. The RJV-CI plus MSI model showed an optimism-corrected AUC of 0.774. Conclusions: Prespinal SI, MSI, DSI, and RJV-CI were associated with PSH in this cohort. Models combining RJV-CI with SI or MSI showed numerically higher discrimination than the individual predictors. The derived cutoff values should be considered exploratory and require external validation before routine clinical use.