To Örebro University

Background: A recent study demonstrated that reflux is associated with impaired pressure augmentation in the esophagogastric junction (EGJ), caused by diaphragmal contractions during inspiration. It is unknown whether this augmentation is influenced by opioids. Swallowing difficulties can be a poorly recognised side effect of remifentanil. Here, we investigated whether remifentanil influences inspiratory EGJ augmentation and evaluated subjective swallowing difficulties induced by remifentanil. We also used the peripheral opioid receptor antagonist methylnaltrexone to evaluate whether these effects are centrally or peripherally mediated.

Methods: Ten healthy volunteers participated in a double-blind, randomised, cross-over trial at the University Hospital in orebro, Sweden. They were studied on two different occasions, during which they were randomly assigned to receive either methylnaltrexone 0.15mg/kg or saline subcutaneously 30min before the target-controlled infusion of remifentanil of 3ng/mL. EGJ pressures were measured by high-resolution manometry. Swallowing difficulties were assessed when volunteers performed dry swallows. The outcomes were the differences in EGJ pressures at baseline and during remifentanil infusion and with methylnaltrexone vs. placebo. Differences in swallowing difficulties before and during remifentanil, and with methylnaltrexone vs. placebo were also recorded.

Results: Remifentanil decreased the inspiratory EGJ augmentation and induced swallowing difficulties. No statistically significant differences between methylnaltrexone and placebo occasions were found.

Conclusions: Remifentanil may increase risk for gastroesophageal reflux by decreasing the inspiratory EGJ augmentation. The clinical significance of remifentanil-induced swallowing difficulties is to be studied further. Given the limited sample size, it cannot be concluded whether these effects are centrally or peripherally mediated.