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

Objective: To evaluate endotracheal tube intracuff pressure (P) changes over time and the effect of these changes on air leak pressure (P).

Study Design: Prospective experimental study.

Animals: A group of nine healthy adult Beagle dogs.

Methods: In part I, in vitro measurements of P 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 was evaluated at P of 25 mmHg. Subsequently, P was reset to 25 mmHg (baseline) and P measurements were recorded every 5 minutes for 1 hour. Subsequently, a second P measurement was recorded at the current P. The data were analyzed using Wilcoxon signed-rank test, repeated measures anova and Mann-Whitney U test.

Results: In part I, P 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 decreased to <18 mmHg at 10 minutes and significant decreases were recorded at 15-60 minutes (P range: 10.0 ± 4.9 to 13.4 ± 6.3 mmHg, mean ± standard deviation). Significant differences were observed between the first and second P measurements (p = 0.034). P 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 over time were measured. P may decrease during anesthesia and increase the risk for silent pulmonary aspiration. The results indicate the need for testing P more than once, especially at 10 minutes after the onset of anesthesia.