The effects of remifentanil and dexmedetomidine on the gastro-oesophageal pressure gradient: A crossover randomised controlled volunteer trial

Remifentanil and dexmedetomidine are sedative agents used both in anaesthetic and critical care practice. Their effects on the gastro-oesophageal pressure gradient and hence on the potential risk for regurgitation have not been quantified. The aim of this study was to measure and compare the effects of both agents on the gastro-oesophageal pressure gradient. The study used a randomised, double blinded crossover study design, and 16 healthy volunteers were sedated on two separate occasions. Baseline lower oesophageal sphincter pressure (26 and 28 mmHg for dexmedetomidine and remifentanil, respectively) and gastro-oesophageal pressure gradient (20 mmHg for both dexmedetomidine and reminfentanil) were recorded. Then, each volunteer received increasing doses of target-controlled infusions of dexmedetomidine (1, 2, 4, 6 ng/ml) or remifentanil (1, 2, 3, 4 ng/ml). Each dose level was maintained for 20 minutes, and both lower oesophageal sphincter pressure and gastro-oesophageal pressure gradient were continuously recorded. Measurements were averaged. Out of 16 subjects recruited, data were analysable from 11 (aged 18-54 years, body mass index 17.7-27.9 kg/m², five men and six women). The dose regimens of both agents provided similar profiles of progressive sedation over time, with sedation scores reaching a minimum of -2 on the 'observer's assessment of alertness and sedation score' with both medications. With dexmedetomidine, the bispectral index gradually decreased in line with sedation scores (<i>P</i><0.05), but remifentanil produced little change in the bispectral index from baseline. Both agents decreased gastro-oesophageal pressure gradient (<i>P</i><0.001) similarly, (<i>P</i>=0.199), in line with the decreases in sedation scores. In conclusion, when remifentanil or dexmedetomidine are administered to provide sedation they induce similar decreases in gastro-oesophageal pressure gradient. This may put patients at comparable risk of gastro-oesophageal reflux.