Effect of epidural opioids on gastric emptying in labour

The effect of epidural opioids on gastric emptying was studied in 36 women in labour. Women who had received one dose of epidural bupivacaine were randomised to receive 10 ml of bupivacaine 0.25% alone (n = 8) with fentanyl 50 microg (n = 8) or with diamorphine 2.5 mg (n = 8), or 10 ml of bupivacaine 0.125% alone (n = 4) or with fentanyl 100 microg (n = 4) or with diamorphine 5 mg (n = 4) when they first requested a top-up. Mean+/-SD fentanyl concentrations measured at delivery were, in maternal venous plasma (MV) 0.72+/-0.19 ng/ml and in umbilical venous plasma (UV) 0.75+/-0.3 ng/ml. The mean dose-delivery interval was 280 min (range 107-608 min) and there was a negative correlation between UV/MV and dose-delivery interval. Gastric emptying was assessed by measuring paracetamol absorption following an oral dose of 1.5 g given 30 minutes after the study top-up. Time to peak plasma paracetamol concentration was significantly delayed in the groups given fentanyl 50 and 100 microg and diamorphine 5 mg, compared to the groups given bupivacaine alone, and peak concentration was significantly reduced in the group given diamorphine 5 mg. It is concluded that epidural fentanyl 50 and 100 mg and epidural diamorphine 5 mg delay gastric emptying. The addition of 2.5 mg diamorphine has no significant effect.