Category II Fetal Heart Rate Tracing
Conditions
Keywords
bolus intravenous fluid administration, continuous intravenous fluid administration, Category II fetal heart rate tracing, electronic fetal monitoring, intrauterine resuscitation
Brief summary
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.
Detailed description
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.
Interventions
DRUGNormal saline bolus infusion
Participants were prescribed 1,000 mL of normal saline through a 21-gauge cannula and the same volumetric infusion pump. The first 500 mL was administered at 1,000 mL/h during the first 30 minutes. The remaining 500 mL was then administered at 150 mL/h. The intervention continued until the attending declared Category I recovery or until 120 minutes.
DRUGContinuous normal saline infusion
Participants were prescribed 1,000 mL of normal saline through a 21-gauge cannula and the same volumetric infusion pump. Normal saline was administered continuously at 150 mL/h throughout. The intervention continued until the attending declared Category I recovery or until 120 minutes.
Sponsors
Queen Savang Vadhana Memorial Hospital, Thailand
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
DOUBLE (Subject, Outcomes Assessor)
Masking description
Participants were not informed of their group assignment. The attending physician assessed EFM tracings from a separate room without knowledge of allocation. Two independent reviewers re-adjudicated the baseline and 30-minute EFM tracings after delivery. They were masked to allocation, real-time classification, and each other's assessments. The statistician received coded group labels before unblinding. The resident and bedside nurse were not masked.
Intervention model description
Two-arm parallel-group randomised controlled trial with 1:1 allocation ratio. Participants were randomly assigned to either intravenous fluid bolus or continuous infusion and remained in their assigned group throughout the study.
Eligibility
Sex/Gender
FEMALE
Age
20 Years to 35 Years
Healthy volunteers
No
Inclusion criteria
* Singleton pregnancy * Thai nationality * Gestational age of 37 weeks or more * Maternal age from 20 to 35 years * Cephalic presentation * Category II electronic fetal monitoring tracing during labor
Exclusion criteria
* Pre-existing cardiac, pulmonary, thyroid, or overt diabetic disease * Pre-eclampsia or gestational diabetes * Suspected fetal structural anomaly, growth restriction, arrhythmia, or chromosomal abnormality * Recent magnesium sulfate or opioid analgesia * Oligohydramnios
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| First recovery from Category II to Category I EFM tracing within 30 minutes | 30 minutes | Proportion of participants with first recovery from Category II to Category I electronic fetal monitoring tracing within 30 minutes of intervention initiation, classified using the NICHD three-tier system. First Category I recovery was an absorbing endpoint. A later observed Category II classification did not reverse recovered endpoint status. Non-recovery was persistent Category II or progression to Category III. Classification was performed in real time by the masked attending outcome assessor. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| First recovery from Category II to Category I EFM tracing within 60 minutes | 60 minutes | Cumulative proportion of participants with first recovery from Category II to Category I electronic fetal monitoring tracing within 60 minutes of intervention initiation, classified using the NICHD three-tier system. First Category I recovery was an absorbing endpoint. A later observed Category II classification did not reverse recovered endpoint status. Non-recovery by 60 minutes was persistent Category II or progression to Category III. |
| First recovery from Category II to Category I EFM tracing within 120 minutes | 120 minutes | Cumulative proportion of participants with first recovery from Category II to Category I electronic fetal monitoring tracing within 120 minutes of intervention initiation, classified using the NICHD three-tier system. First Category I recovery was an absorbing endpoint. A later observed Category II classification did not reverse recovered endpoint status. Non-recovery by 120 minutes was persistent Category II or progression to Category III. |
| Mode of delivery | At delivery | Route of delivery classified as vaginal delivery or caesarean section. |
| Neonatal Intensive Care Unit (NICU) admission | Within 24 hours of delivery | Proportion of neonates admitted to the neonatal intensive care unit following delivery. |
| Apgar score at 1 minute | 1 minute after delivery | Proportion of neonates with 1-minute Apgar score below 7 |
| Apgar score at 5 minutes | 5 minutes after delivery | Proportion of neonates with 5-minute Apgar score below 7 |
Countries
Thailand
Outcome results
None listed