The delay of gastric emptying induced by remifentanil is not influenced by posture

Posture has an effect on gastric emptying. In this study, we investigated whether posture influences the delay in gastric emptying induced by opioid analgesics. Ten healthy male subjects underwent 4 gastric emptying studies with the acetaminophen method. On two occasions the subjects were given a continuous infusion of remifentanil (0.2 microg. kg(-1). min(-1)) while lying either on the right lateral side in a 20 degrees head-up position or on the left lateral side in a 20 degrees head-down position. On two other occasions no infusion was given, and the subjects were studied lying in the two positions. When remifentanil was given, there were no significant differences between the two postures in maximal acetaminophen concentration (right side, 34 micromol. L(-1); versus left side, 16 micromol. L(-1)), time taken to reach the maximal concentration (94 versus 109 min), or area under the serum acetaminophen concentration time curve from 0 to 60 min (962 versus 197 min. micromol. L(-1)). In the control situation, there were differences between the postures in maximal acetaminophen concentration (138 versus 94 micromol. L(-1); P < 0.0001) and area under the serum acetaminophen concentration time curves from 0 to 60 min (5092 versus 3793 min. micromol. L(-1); P < 0.0001), but there was no significant difference in time taken to reach the maximal concentration (25 versus 47 min). Compared with the control situation, remifentanil delayed gastric emptying in both postures. We conclude that remifentanil delays gastric emptying and that this delay is not influenced by posture.