Use of the shock index to predict maternal outcomes in women referred for postpartum hemorrhage

Objective: To evaluate the clinical significance of various vital signs in women referred for postpartum hemorrhage (PPH). Methods: This retrospective study included patients with primary PPH who were referred to Korea University Medical Center, Ansan, between January 1, 2004, and December 31, 2016. We analyzed data for systolic and diastolic blood pressure, heart rate, and shock index (heart rate divided by systolic blood pressure) at time of arrival. Significant morbidity, such as massive transfusion, invasive procedures, and admission to the intensive care unit were reviewed. We used the area under the receiver operating characteristic curve (AUROC) for each vital sign to predict adverse maternal outcomes. Sensitivity, specificity, and negative and positive predictive values were assessed. Results: 118 women with PPH were identified. The shock index had the highest AUROC to predict massive transfusion (0.815, 95% confidence interval [CI] 0.727–0.883). A shock index greater than 0.9 had 93.8% (95% CI 69.8–99.8) sensitivity and 51.2% (35.1–67.1) specificity for prediction of massive transfusion, and 93.6% (78.6–99.2) sensitivity and 31.0% (15.3–50.8) specificity for prediction of invasive procedures. Conclusion: The shock index has significant ability to predict adverse outcomes of PPH compared with other initial vital signs when patients are referred.