Hemodynamic effects of nifedipine tocolysis

To describe the effects of nifedipine tocolysis on blood pressure and heart rate in non-hypertensive women.

This was a retrospective study from 2001 to 2011 to compare blood pressures and heart rates among non-hypertensive women on nifedipine tocolysis up to 8 h after nifedipine initiation. Measurements at 20-60 and 61-120 min were compared to assess the differential effects of dosing on hemodynamics and reflected the effects of the initial and complete loading doses, respectively. Charts were reviewed for hypotension-related emergent delivery.

One hundred and thirty-eight patients were included. Over the 8-h study interval, mean systolic blood pressure (P < 0.001) and mean diastolic blood pressure (P < 0.001) decreased by 5 mmHg and heart rate increased by 4 b.p.m. (P < 0.001). Systolic and diastolic blood pressures were unchanged from baseline up to 120 min at all doses. Heart rate increased at both 20-60 and 61-120 min when all doses were considered (P < 0.001), but differential dosing effects were not observed. Rates of tachycardia increased (P < 0.001), but rates of hypotension were unchanged. No hypotension-related emergent deliveries occurred.

Nifedipine tocolysis was associated with hemodynamic changes in non-hypertensive women. Tachycardia was increased but hypotension was unaffected, supporting the general safety of nifedipine in this setting.