Recovery Rate From Category II to Category I EFM Tracings in Pregnant Women Receiving Bolus vs Continuous Intravenous Fluid Administration

Overview

This randomized trial compared a normal saline bolus regimen with continuous normal saline infusion. The participants were low-risk pregnant women at term with Category II fetal heart rate tracings. Both groups were prescribed 1,000 mL of normal saline through the same volumetric infusion pump. The bolus group received 500 mL at 1,000 mL/h during the first 30 minutes, followed by 150 mL/h. The continuous group received 150 mL/h throughout. The primary outcome was first recovery from Category II to Category I within 30 minutes. Both groups also received standard intrauterine resuscitation. Fetal heart rate tracings were assessed at 30, 60, and 120 minutes.

Intravenous fluid is a component of intrauterine resuscitation for Category II fetal heart rate tracings. No randomized trial had directly compared bolus and continuous intravenous fluid administration. Both arms were prescribed 1,000 mL of normal saline through a 21-gauge cannula and the same volumetric infusion pump. The bolus group received 500 mL at 1,000 mL/h during the first 30 minutes. The remaining 500 mL was then administered at 150 mL/h. The continuous group received 150 mL/h throughout. Programmed delivery by 30 minutes was approximately 500 mL in the bolus group and 75 mL in the continuous group. Resuscitation continued until the attending declared Category I recovery or until 120 minutes. Both groups received standard intrauterine resuscitation. This included left lateral positioning, oxytocin discontinuation where applicable, and oxygen at 10 L/min through a face mask. The primary outcome was first recovery from Category II to Category I within 30 minutes. First Category I recovery was an absorbing endpoint. A later observed Category II classification did not reverse recovered endpoint status. The participant and attending outcome assessor were masked to allocation. Two masked reviewers independently re-adjudicated the fetal heart rate classifications. A trained operator measured the inferior vena cava collapsibility index and umbilical artery Doppler pulsatility index at baseline and 30 minutes. The primary analysis used Fisher's exact test, risk difference, relative risk, and number needed to treat.