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

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.