To the Editor:--It is occasionally difficult to insert a nasogastric tube in the anesthetized patient or a gastroscope in an awake patient. I report two cases that illustrate a potential application of the laryngeal mask airway (LMA) to improve access to the upper gastrointestinal tract.
An ASA physical status 1, 46-yr-old, 80-kg man presented for awake diagnostic fiberoptic gastroscopy. Topical anesthesia using 10% lidocaine spray and sedation using 50 mg propofol were administered. The gastroscope was passed into the oropharynx through an oxygenating mouth piece, and the vocal cords and pharynx appeared normal. However, passage of the gastroscope became difficult when the tip repeatedly contacting the glottis. A variety of maneuvers were attempted to facilitate passage of the scope, including further topicalization and sedation, manipulation of the head and neck, and digital manipulation of the gastroscope tip. Eventually, the patient was asked to swallow a semiinflated #4 LMA in an attempt to shield the glottis from the gastroscope. A clear airway immediately was obtained, and the device was well tolerated. The mouth piece was reinserted, and the gastroscope was passed behind the semiinflated cuff of the LMA and into the esophagus on the first attempt. The LMA was left in place during the procedure, and no abnormalities were found.
An ASA physical status 2, 65-yr-old, 98-kg woman required insertion of a nasogastric tube during a laparotomy. Initial attempts using a blind and then laryngoscope-guided technique with Magill's forceps were unsuccessful. A #4 LMA was placed easily behind the tracheal tube using the standard technique, and the cuff was semiinflated. A laryngoscope was inserted behind the proximal part of the LMA cuff, and the LMA was elevated to expose the posterior pharyngeal wall. The nasogastric tube was grasped with Magill's forceps from the oropharynx and moved along the posterior pharyngeal wall toward the hypopharynx. It passed through the upper esophageal sphincter and into the stomach on the first attempt. The LMA then was removed.
By physically isolating the glottis from the upper esophagus and forming a mold around it, the LMA directs instrumentation passed along the posterior pharyngeal wall toward the esophagus, shields anterior pharyngeal structures from accidental impact, and allows 100% Oxygen 2 to be administered. Although the correctly placed LMA tip occupies the entire hypopharynx, the tissues and tip are sufficiently flexible to allow passage of instrumentation into the esophagus. Pace et al. showed that an 8-mm esophageal tube and an adult LMA may occupy the pharynx simultaneously without interfering with LMA function. .
In summary, these two cases illustrate the potential of the LMA as a guide to the gastrointestinal tract in awake and anesthetized patients.
J. Brimacombe, F.R.C.A., Clinical Associate Professor, University of Queensland, Department of Anaesthesia and Intensive Care, Cairns Base Hospital, Cairns, 4870 Australia.