The effect of high-dose versus low-dose epidural fentanyl on gastric emptying in nonfasted parturients

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 (T 2 h). MAIN OUTCOME MEASURES The primary outcome was CSA at T 2 h comparing high-dose versus low-dose fentanyl. Secondary outcomes included change in CSA between baseline and T 2 h. Sub-group analysis compared stomach content at T 2 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 T 2 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 T 2 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 T 2 h. CONCLUSION The CSA at T 2 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.