The Risk of Aspiration in Laryngeal Mask Airway: Laryngeal Mask Airway vs Endotracheal Tube

ABSTRACT

BACKGROUND: There were several studies for the incidence of gastroesophageal reflux associated with the laryngeal mask airway(LMA), but the results of those studies were much different much different from one another. The aim of this study was to compare the incidence of gastroesophageal reflux and regurgitation of gastric contents between the LMA and the endotracheal tube(ETT). METHOD: Ninety patients scheduled for elective orthopedic surgery with a standardized general anesthetic technique were randomly allocated to receive either a LMA(n-49) or a ETT(n=41) for airway management. The esophageal manometry was carried out for the exclusion of esophageal motility disorders and the 24-hour ambulatory pH metry was done from one day before the operation. A methylene blue(50mg) capsule was swallowed just before the induction and the simultaneous recordings of pH were maintained during anesthesia. At the end of anesthesia, the episodes of regurgitation of gastric contents above hypopharynx were analyzed by the pharyngeal blue staining and the pH metric data were analyzed for the detection of gastroesophageal relux episodes during anesthesia. RESULTS: There was no significant difference in the incidence of gastroesophageal relux(pH< or =4) between two groups; only two patients in LMA and three patients in ETT had reflux episodes during the removal or arousal phase. There was no episode of the pharyngeal blue staining in both group. All of the gastroesophageal reflux patients in both group developed a cough or straining during those phases. There was no clinical evidence of aspiration of gastric contents in both group. CONCLUSION: In comparison with ETT, use of LMA does not appear to increase the incidence of gastroesophageal reflux and regurgitation above hypophryngeal level in positive pressure ventilating patients during long surgical procedures. Therefore, the risk of aspiration in LMA will not be much more than ETT.