The lowest effective intracuff pressure of the esophagus obstruction tube to prevent reflux of gastric contents: a study on rabbits.

PURPOSE: To determine the lowest effective cuff pressure of the esophageal obstruction tube to prevent reflux of gastric contents in rabbits. METHODS: Twenty-two New Zealand white rabbits (2.0-2.5 kg) were anesthetized. An esophageal obstruction tube, an esophageal observation tube, and a gastric tube were inserted into the esophagus and stomach, respectively. Normal saline containing methylene blue was injected into the stomach for an animal model of gastric contents reflux. Possible saline reflux was observed through the esophageal observation tube. It was considered "regurgitation" when the saline flowed out, and "no regurgitation" when the saline did not. When a "regurgitation" result was obtained in a particular rabbit, the intracuff pressure was increased by 10 cm H(2)O in the following rabbit and vice versa. The trial was not terminated until six crossover points were observed from "no regurgitation" to "regurgitation." A probit regression model was used to analyze the effective intracuff pressure of the esophagus obstruction tube after 50 % and 95 % of the rabbits showed no reflux. RESULTS: The lowest effective intracuff pressure to prevent reflux of gastric contents in 50 % of rabbits from the Dixon up-down method was 61.67 ± 8.16 cm H(2)O. The intracuff pressures at which there was 50 % and 95 % probability of lack of gastric contents reflux from a probit regression model were 61.95 and 74.39 cm H(2)O, respectively. CONCLUSION: The insertion of an esophageal obstruction tube before endotracheal intubation can be an acceptable method for preventing the reflux of gastric contents in most rabbits under light anesthesia.