Cricoid pressure decreases lower oesophageal sphincter tone in anaesthetized pigs

Purpose: Previous studies have shown a decrease of lower oesophageal sphincter (LOS) tone during stimulation of the upper oesophageal sphincter. Therefore, we hypothesized that during anaesthesia, cricoid pressure could result in a decrease in LOS pressure. Methods: The LOS and oesophageal barrier pressures (BrP = LOSP minus gastric pressure) were obtained in 11 anaesthetized pigs with intraabdominal pressure of 15 mmHg using a manometric method (perfused catheters) before and during firm application of cricoid pressure. Reflux was assessed with concomittant recording of the lower oesophageal pH. Results: Cricoid pressure decreased LOSP from 31.0 +/- 14.5 mmHg to 26.1 +/- 12.7 mmHg (P < 0.001) leading to a 35% reduction of oesophageal barrier pressure (9 +/- 10.3 mmHg vs 13.7 +/- 12.4 mmHg; P < 0.001). No episodes of reflux were recorded. Conclusions: This study shows that cricoid pressure decreases LOS tone in anaesthetized pigs. Although no gastrooesophageal reflux was recorded, this study suggests that, if cricoid pressure does not completely occlude the oesophagus, the decrease of oesophageal barrier pressure induced could favour the appearance of pulmonary aspiration.