Effect of cuffed and uncuffed endotracheal tubes on the oropharyngeal oxygen and volatile anesthetic agent concentration in children

摘要

Background: Over the past 5 years, there has been a change in the clinical practice of pediatric anesthesiology with a transition to the use of cuffed instead of uncuffed endotracheal tubes (ETTs) in infants and children. As the trachea is sealed, one advantage is to eliminate the contamination of the oropharynx with oxygen which should be advantageous during adenotonsillectomy where there is a risk of airway fire. The current study prospectively assesses the oropharyngeal oxygen and volatile anesthetic agent concentration during adenotonsillectomy in infants and children. Methods: Following the induction of general anesthesia in patients scheduled for adenoidectomy, tonsillectomy or adenotonsillectomy, the trachea was intubated. The use of a cuffed or uncuffed ETT and the use of spontaneous (SV) or positive pressure ventilation (PPV) were at the discretion of the anesthesia team. The oxygen concentration was kept at 100% oxygen until the study was completed. Following placement of the mouth gag, the otolaryngolist placed into the oropharynx a small bore catheter, which was attached to a standard anesthesia gas monitoring device which sampled the gas at 150. mL/min. The concentration of the oxygen and the concentration of the anesthetic agent in the oropharynx were measured for 5 breaths. Results: The cohort for the study included 200 patients ranging in age from 1 to 18 years. With the use of a cuffed ETT and either SV or PPV, the oxygen concentration in the oropharynx was 20-21% and the volatile agent concentration was 0% in all 118 patients. With the use of an uncuffed ETT and the administration of 100% oxygen, there was significant contamination of the oropharynx noted during both PPV and SV. The mean oxygen concentration was 71% during PPV with an uncuffed ETT and 65% during SV with an uncuffed ETT. In these patients, the oropharyngeal oxygenation concentration exceeded 30% in 73 of the 82 patients (89%). The oropharyngeal oxygen and agent concentration was greater when the leak around the uncuffed ETT was ≥10cmH 2O versus less than 10cmH 2O and when the leak around the uncuffed ETT was ≥15cmH 2O versus less than 15cmH 2O. Conclusions: With the use of an uncuffed ETT and the administration of 100% oxygen, there was significant contamination of the oropharynx noted during both PPV and SV. The oropharyngeal concentration of oxygen is high enough to support combustion in the majority of patients. The use of a cuffed ETT eliminates oropharyngeal contamination with oxygen during the administration of anesthesia and may be useful in limiting the incidence of an airway fire.