OP15.07: Use of the cardiovascular resistance index to predict labetalol non‐response in the management of hypertensive crisis during pregnancy

To determine the role of hemodynamic and biophysical markers at hypertensive crisis to predict treatment failure with labetalol. This cohort study involved pregnancies with hypertensive crisis upon admission or during hospitalisation. Heart rate (HR), systolic (SBP), and diastolic blood pressure (DBP) were recorded before IV-labetalol administration. The cardiovascular resistance index (CVRI) was calculated as SBP/HR. Non-responders to labetalol were identified if maximum dose was reached or if a Caesarean section was required due to fetal distress during treatment. A hyperdynamic profile was defined as HR>90 and estimated fetal weight (EFW) >10th percentile. A high-resistance profile was characterised by EFW < 10th percentile or HR< 90. Responders and non-responders were compared using Mann-Whitney test. Time-to-response in both profiles was assessed using Cox regression and Kaplan-Meier curves. Finally, a multivariate logistic regression analysis was conducted to determine factors associated with therapeutic failure with beta-blockers. Out of the 44 pregnancies examined, 57% (n = 25) were identified as non-responders. Responders exhibited a higher incidence of the hyperdynamic profile compared to non-responders (26% vs. 4%; p = 0.03). Additionally, non-responders displayed a significantly higher CVRI compared to responders (2.27 [2.03-2.48] vs. 1.90 [1.47-2.14]; p = 0.002). Time-to-response was markedly shorter in the hyperdynamic profile group compared to the high-resistance profile (p < 0.05). Multivariate analysis revealed that lower gestational age, higher SBP, and lower HR were the most reliable predictors of non-response to labetalol (Sensitivity = 63%; FPR = 5%; AUC = 0.87; LHR(+) = 11.9). Non-response to labetalol for hypertensive crisis in pregnancy is correlated with a higher cardiovascular resistance index and lower gestational age. The recognition of a specific hemodynamic profile is crucial for tailoring personalised management of severe hypertension during pregnancy.