A Comparison of LMA, Cuffed and Uncuffed Endotracheal Tubes in Preventing Nitrous Oxide Emission during Pediatric Anesthesia

Abstract

Epidemiological studies have revealed as increased incidence of spontaneous abortions, reduced fertility, congenital abnormalities, leukemia, lymphoma, hepatic disease and renal disease in healthcare personnel chronically exposed to trace concentrations of anesthetic gases. For this reason, there is sufficient concern to warrant positive steps to control the airborne levels of inhalation anesthetic agents. It is well documented that nitrous oxide exposure is greater during pediatric anesthesia than during adult anesthesia. This is attributed to the use of inhalation induction technique and uncuffed endotracheal tubes in the population. Traditional intra-operative airway management within the pediatric population undergoing general anesthesia has been accomplished primarily with the uncuffed endotracheal tube. However, the laryngeal mask airway and the cuffed endotracheal tube may offer the conscientious anesthesia care provider a more effective choice for reducing waste anesthetic gas emissions. The purpose of this study was to quantify and compare the amount of nitrous oxide emitted around the laryngeal mask airway, the cuffed endotracheal tube, and the uncuffed endotracheal tube during pediatric anesthesia. We hypothesized that both the cuffed endotracheal tube and the laryngeal mask airway would emit less nitrous oxide into the atmosphere than the uncuffed endotracheal tube during pediatric general anesthesia. <p>Sixty-seven ASA I and II children, ages 1-8 years, undergoing elective surgery requiring general anesthesia completed the study. Those subjects requiring intubation were randomized to receive a cuffed (n=16) or uncuffed endotracheal tube (n=26) after obtaining informed, written consent. Those subjects not requiring tracheal intubation received the laryngeal mask airway (n=25) as an airway adjunct. The amount of nitrous oxide emitted around each airway device was measured in parts per million (ppm) with a transportable infrared nitrous oxide detector. Nitrous oxide emission levels in the cuffed endotracheal tube group were zero ppm in all subjects. The mean nitrous oxide levels were significantly higher in the uncuffed endotracheal tube group (50.2 ± 86 ppm) compared to the laryngeal mask airway group (7.8 ± 22 ppm). The results of this study suggest that the cuffed endotracheal tube is the most efficient in preventing nitrous oxide emission during pediatric anesthesia. In addition, the laryngeal mask airway is more efficient at preventing nitrous oxide emission than the uncuffed endotracheal tube. Clinically, in order to limit nitrous oxide exposure, the use of the cuffed endotracheal tube and laryngeal mask airway may be best when indicated. This practice could decrease nitrous oxide exposure to operating room personnel.