Shock index reference ranges in the first 48 h postpartum following elective cesarean delivery: A prospective cohort study.

PURPOSE: To determine the reference values for the shock index (SI) in postpartum patients undergoing elective cesarean delivery with regional anesthesia.

METHODS

This prospective study was conducted at our tertiary center between August 1, 2023, and March 1, 2024. We calculated the reference values for the SI within the first 48 h postpartum for patients who underwent elective cesarean delivery after the 34th week of gestation. We excluded cases of vaginal delivery, post-term delivery (≥42 weeks of gestation), multiple pregnancies, stillbirths, fetal abnormalities, maternal cardiac disease, anemia, untreated hypo- or hyperthyroidism, and any hypertensive disorders diagnosed before or during pregnancy. Data collection, measurement of vital signs, and the administration of fluids pre-, intra-, and post-operatively, as well as the use and dosing of uterotonic agents for the prevention of postpartum hemorrhage (PPH), were standardized for all patients.

RESULTS

Our final analysis included 311 patients, with a mean SI value of approximately 0.7 (0.67-0.77) for all measurement performed within the first 48 h of the postpartum period. Further analyses revealed that the 90th and 95th percentiles of SI were around 0.9 throughout the study period. Additionally, SI reference values analyzed at different time points were consistent. Our analysis demonstrated that SI values were not influenced by the presence of a previous caesarean section, the administration of oxytocin or carbetocin, or parity in this particular cohort. Our analyses of vital signs also indicated that the 95th percentile of heart rate (HR) ranged from 96 to 100 bpm.

DISCUSSION: An SI value of 0.9 represents the 95th percentile of SI values throughout the first 48 h of the postpartum period. Any greater value should be evaluated carefully for potential adverse outcomes.