Changes in endotracheal tube intracuff pressure and air leak pressure over time in anesthetized Beagle dogs

Abstract

Objective To evaluate endotracheal tube intracuff pressure (P-cuff) changes over time and the effect of these changes on air leak pressure (P-leak). Study design Prospective experimental study. Animals A group of nine healthy adult Beagle dogs. Methods In part I, in vitro measurements of P-cuff were recorded for 1 hour in eight endotracheal tubes subjected to four treatments: room temperature without lubricant (RT0L), room temperature with lubricant (RTWL), body temperature without lubricant (BT0L), and body temperature with lubricant (BTWL). In part II, nine dogs were endotracheally intubated and P-leak was evaluated at P-cuff of 25 mmHg. Subsequently, P-cuff was reset to 25 mmHg (baseline) and P-cuff measurements were recorded every 5 minutes for 1 hour. Subsequently, a second P-leak measurement was recorded at the current P-cuff. The data were analyzed using Wilcoxon signed-rank test, repeated measures ANOVA and Mann-Whitney U test. Results In part I, P-cuff differed significantly between the RT0L and RTWL treatments at 5-60 minutes, and between the BT0L and BTWL treatments at 5-35, 55 and 60 minutes (p < 0.05). In part II, compared with baseline pressures, mean P-cuff decreased to < 18 mmHg at 10 minutes and significant decreases were recorded at 15-60 minutes (P-cuff range: 10.0 +/- 4.9 to 13.4 +/- 6.3 mmHg, mean +/- standard deviation). Significant differences were observed between the first and second P-leak measurements (p = 0.034). P-leak decreased in six of nine dogs, was not changed in two dogs and increased in one dog. Conclusions and clinical relevance Significant decreases in P-cuff over time were measured. P-leak may decrease during anesthesia and increase the risk for silent pulmonary aspiration. The results indicate the need for testing P-cuff more than once, especially at 10 minutes after the onset of anesthesia.