Title: Gastroscopy in awake and anaesthetized patients using a modified laryngeal mask
Abstract: EDITOR: Upper gastrointestinal endoscopy is possible with the laryngeal mask airway [1], but may be difficult since the gastroscope has to be guided behind the partially deflated cuff and airway control may be compromised. A prototype laryngeal mask airway was described by Brain in 1995 that had a small second tube for drainage of regurgitated fluid or placement of a gastric tube [2]. We describe two cases where a modification of this device was used for gastroscopy. The modified laryngeal mask airway was constructed from identical materials to those used in the commercial device (Fig. 1). It has a second trumpet-shaped mask, which rests above the upper oesophageal sphincter, and a second cuff mounted on the dorsal surface to increase the seal pressure of the glottic mask and provide a firm anchor for the oesophageal mask. The interior of the dorsal cuff communicates with the ventral cuff so that the two cuffs inflate simultaneously via a single pilot balloon. The oesophageal mask and drainage tube were formed by invaginating the tip and welding it to a 12-mm internal diameter tube, which was fixed to the backplate of the mask. The dorsal cuff forms a partial hemisphere covering the back of the mask and enclosing this drainage tube which is positioned lateral to the main airway tube. The cuff had similar dimensions to the size 5 laryngeal mask airway.Fig. 1: The modified laryngeal mask with a gastroscope passed through the drainage tube.Case 1 A 45-year-old, 72-kg man was scheduled for an elective gastroscopy to investigate epigastric pain and occasional reflux (once per week). He refused sedation and insisted on a general anaesthetic. He was fasted for 6 h. The risk: benefits of intubation vs. the modified laryngeal mask airway were discussed and the patient consented to have the modified laryngeal mask airway inserted. The modified laryngeal mask airway had been approved for use by the hospital ethics committee. Routine patient monitoring was applied. Induction of anaesthesia was with midazolam 0.04 mg kg−1 and propofol 3 mg kg−1. The modified LMA was easily inserted and had a good seal (> 40 cmH2O). Anaesthesia was maintained with intermittent boluses of propofol and the patient was allowed to breathe 100% oxygen spontaneously. A lubricated gastroscope (10.5 mm external diameter) was passed at the first attempt into the stomach. The gastroscopy lasted 5 min and was uneventful. SpO2 remained at 100% throughout the procedure. No macroscopic pathology was detected. The modified laryngeal mask airway was removed when the patient was able to open his mouth to command. The patient was discharged a few hours later. Case 2 A 73-year-old, 58-kg man with chronic pulmonary airway disease was scheduled for elective gastroscopy to investigate weight loss and epigastric pain. He had an FEV1 of 0.45 L, and SpO2 89% breathing room air. He had fasted for 12 h. It was considered that ventilatory support might be required during the procedure. The patient consented to have the modified laryngeal mask airway inserted under topical anaesthesia and sedation. Routine monitoring was applied. After topical application of 10% lidocaine spray and sedation with midazolam 0.03 mg kg−1, the modified laryngeal mask airway was easily inserted. The efficacy of seal was not assessed. The patient breathed 100% oxygen spontaneously and remained conscious throughout. A similar gastroscope to Case 1 was passed at the first attempt. The gastroscopy lasted 5 min and revealed a gastric carcinoma. Arterial oxygen saturation was 100% throughout the procedure. The modified laryngeal mask airway was removed at the end of the procedure. The patient stated that he would be happy to have the same anaesthetic if the procedure needed to be repeated. We have shown that gastroscopy is feasible with the modified laryngeal mask airway in both awake and anaesthetized patients. It is generally considered that use of the laryngeal mask airway is contraindicated in patients with upper gastrointestinal pathology. However, the risk of regurgitation/aspiration was probably low: (a) since neither patient had symptoms of severe reflux; (b) if regurgitation had occurred, the fluid may have escaped up the drainage tube, as suggested by earlier case reports [3,4], or been removed though the suction port of the gastroscope, and (c) once the gastroscope was in the stomach, any fluid present could be removed reducing the risk still further. Interestingly, Bapat and Verghese reported that reflux was extremely rare during anaesthesia with the laryngeal mask airway, even in patients with some risk factors for regurgitation [5]. Gastroscopy is usually conducted in topicalized, sedated patients (low aspiration risk) or intubated anaesthetized patients (high aspiration risk). Clinical circumstances where the modified laryngeal mask airway might be useful are in the low aspiration risk patient requiring general anaesthesia (Case 1), or in a low aspiration risk patient with severe pulmonary disease who might require ventilatory support during the procedure (Case 2). Avoidance of tracheal intubation may be useful in patients with severe pulmonary disease since the laryngeal mask airway probably interferes less with pulmonary function than the tracheal tube [6-8]. The modified laryngeal mask airway is probably unsuitable for high aspiration risk cases requiring gastroscopy unless already in position following airway rescue. F. AGRÒ University School of Medicine, Campus Bio-Medico, Rome, Italy J. BRIMACOMBE University of Queensland, Cairns Base Hospital, Cairns, Australia C. KELLER Leopold-Franzens University, 6020, Innsbruck, Austria L. PETRUZZIELLO University School of Medicine Campus Bio-Medico, Rome, Italy G. BARZOI University School of Medicine, Campus Bio-Medico, Rome, Italy