The Effect of High-dose Versus Low-dose Epidural Fentanyl on Gastric Emptying in Nonfasted Parturients: A Double-blinded Randomised Controlled Trial

Background: Epidural fentanyl doses above 100 μg have been shown, using the paracetamol absorption test, to reduce gastric emptying in fasted labouring women.

Objective: To investigate the effect of fentanyl dose on gastric emptying in nonfasted labouring women using gastric ultrasonography.

Design: A double-blinded randomised controlled study.

Setting: A tertiary medical centre in Tel Aviv, Israel between 30 July 2020 and 11 October 2020.

Patients: Eighty labouring women with cervical dilation 5 cm or less, at least 18 years age, at least 37 weeks gestation with a singleton pregnancy and cephalad foetus.

Interventions: Women randomised to high (>100 μg) or low (<100 μg) cumulative epidural fentanyl had ultrasound gastric content assessment, measuring antral cross-sectional area (CSA) at epidural placement and 2 h thereafter (T2  h).

Main Outcome Measures: The primary outcome was CSA at T2  h comparing high-dose versus low-dose fentanyl. Secondary outcomes included change in CSA between baseline and T2  h. Sub-group analysis compared stomach content at T2  h according to baseline stomach content, empty (CSA <381 mm2) or full (CSA ≥381 mm2), and high-dose versus low-dose fentanyl.

Results: Data from 80 women were analysed; 63 had empty and 17 had full stomach at baseline. There was no significant difference in CSA at T2  h between high-dose, mean 335 ± SD 133 mm2, versus low-dose fentanyl, mean 335 ± SD 172 mm2, P = 0.991. Change in CSA baseline to T2  h was 46 ± SD 149 mm2 for high and 49 ± SD 163 mm2 for low-dose group, P = 0.931. The subgroup analysis according to baseline stomach content showed no statistically significant differences in CSA at T2  h.

Conclusion: The CSA at T2  h was similar for women who received high-dose versus low-dose epidural fentanyl, measured by ultrasound, in our nonfasted labouring cohort.

Trial Registration: Clinicaltrials.gov number: NCT04202887.