Nitroglycerin Versus Labetalol in Acute Severe Pre-eclampsia

Patients and Methods The study was conducted in the intensive care unit (ICU) of the Obstetrics and Gynaecology Hospital of Ain-Shams University as a randomized, double-blind, and placebo-controlled study on patients diagnosed with severe PE from July 2016 to June 2018. The study was approved by Ethical Research Committee at Ain Shams University (ethical number FMASU R 47/2019) and all participants provided written informed consent.

Woman eligible for this study were aged between 18-40 years old at greater than 34 weeks of gestation having severe PE without severe features (without imminence of eclampsia or clinical manifestations of target organ damage, as per the ACOG criteria) (7). Severe PE was diagnosed by severe hypertension (systolic blood pressure ≥160 mmHg or diastolic blood pressure ≥110 mmHg, repeated measurement should be taken for confirmation no more than 15 minutes later), presence of clinically significant proteinuria (0.3 grams or more of protein in 24-hour urine collection, or urinary protein/creatinine ratio of 30 or more)[8].

Exclusion criteria were patients with chronic hypertension, imminence of eclampsia, target organ damage, active asthma and congestive heart failure. Patients with any known allergy to one of the study drugs are also excluded.

Two hundred patients with severe PE were admitted prepartum to the ICU to stabilize blood pressure. They were randomly assigned to one of two groups (100 in each group): Group N received nitroglycerine intravenous infusion in a concentration of 1 mg/ml, thus 1µg/Kg/min equals to 4.8 ml/hr for an 80 Kg patient. Group L received labetalol intravenous infusion in a concentration of 10 mg/ ml, thus 50 mg/ml equals to 5 ml/hr. The starting infusion rate of the antihypertensive medication was 5 ml/hr. The infusion rate was titrated to stabilize systolic blood pressure (SBP) at 130-140 mmHg and diastolic blood pressure (DBP) at 80-90 mmHg (study end point) by adjusting the infusion rate as required either by maintaining the same infusion rate or by changing its infusion rate by 1 ml/hr up or down according to the clinical condition every 10 minutes. On any abrupt reduction in blood pressure below 120 mmHg for SBP or 80 mmHg for DBP, the infusion was immediately discontinued, and a bolus of 150 ml lactate ringer was given.

Randomization was attained by using orderly numbered, opaque sealed envelopes containing computer-generated random allocations.