176: Applications for shock index in obstetrics

Abstract

Evaluation of post-partum blood loss is traditionally inaccurate. Shock index, a common tool used in the trauma setting to identify patients at risk for massive transfusion, is defined as heart rate divided by systolic blood. Our objective is to evaluate postpartum shock index (SI) values between women who did and did not require blood transfusion due to postpartum hemorrhage (PPH) as a useful tool in obstetrics. This is a retrospective case control study of women who delivered at a single institution in 2018. Delivery data, quantified blood loss (QBL), maternal outcomes data, and vital signs were collected throughout the first 30 minutes postpartum. Primary outcome is to define normal SI at term. Secondary outcomes analyze association between SI and QBL. Analysis was performed using Wilcoxon rank-sum test, and linear, univariate and multivariate regression. Log scaling was applied due to skewness in data. 126 women were studied: 80 experienced PPH and 20 required transfusion. Normal SI at term was 0.7 (Range 0.4-1.1). Increase in SI value was associated with increasing blood loss. For every 0.1 incremental increase in SI, the RR of blood loss was 1.06. SI > 0.9 at 30 minutes postpartum was significantly associated with need for blood transfusion (p 0.003). As a predictor of blood transfusion, this SI 30 minutes postpartum of > 0.9 had PPV value of 26% and NPV of 89%. Increased SI values were associated with greater volume of blood loss and need for blood transfusion in both vaginal and cesarean deliveries. SI predicts need for blood transfusion in women after vaginal or cesarean delivery. SI is positively correlated with intra-partum blood loss. SI is easily obtained and reproducible at the time of delivery. Postpartum SI may be a clinically useful tool in obstetrics.