The Efficacy of Laryngeal Mask Airway Gastro (LMA® Gastro™) in Preventing Hypercarbia in ERCP Patients: A Randomized Controlled Study

Endoscopic retrograde cholangiopancreatography (ERCP) is fast emerging as a therapeutic procedure rather than a diagnostic one, requiring anesthetic support for successful completion of the procedure. The procedure can be uncomfortable especially due to prone positioning, multiple passages of endoscope, air insufflations, dilatation of ductal structures and prolonged duration which requires a high degree of cooperation from patients. A large number of patients need to be given general anesthesia (GA), in order to minimize incidence of adverse respiratory and hemodynamic events in the peri-procedure period. The use of GA with endotracheal intubation (ETT) or supraglottic devices protects the airway, reduces ERCP failure and complication rates. However, ETT involves rigid laryngoscopy with consequent undesirable hemodynamic responses and use of neuromuscular blocking drugs. It also has the disadvantage of a longer recovery time and possibility of injury to the oro-pharynx at insertion.

Moderate to deep sedation is a commonly employed technique for ERCPs, with general anesthesia utilizing an endotracheal intubation being reserved for selected cases. Reported rates of hypoxemia during all endoscopic procedures range from 11 to 50%, and this may be as high as 60% with ERCP. Sustained hypoxia is a major risk factor for peri-procedural cardiac arrhythmias and myocardial ischemia. Respiratory complications that occur during intravenous sedation have a higher risk of hypercapnia than hypoxemia. Patients receiving propofol-based tubeless sedation may be at higher risk of sedation-related adverse events than patients receiving GA. Moreover, when low-flow oxygen is administered through a nasal cannula, the apparent oxygen saturation value is maintained at a normal concentration; however, hypoventilation is sustained, which may result in impaired exhalation. Gradual CO₂ accumulation, and CO₂ concentrations maintained at 60 mmHg or higher, are risk factors for secondary circulatory abnormalities such as an abnormal increase in blood pressure, tachycardia, and arrhythmia.

As the number of gastrointestinal endoscopic interventions and possibilities increased, and the number of patients with severe comorbidities and existing medical conditions, the need for minimally invasive airway devices specially dedicated for endoscopic procedures became relevant. A modified laryngeal tube with a dedicated channel for an endoscope was described as an alternative airway device. This approach was further developed with the introduction of the LMA® Gastro™ Airway, a refined tool in advanced airway management for upper gastrointestinal endoscopy.

The LMA® Gastro™ Airway is a cuffed peri-laryngeal supraglottic airway (SGA) with an endoscopic channel, having a maximum diameter of 14 mm, which suits all standard endoscopes. Its design features include a channel for esophageal intubation, a separate channel with a terminal cuff for lung ventilation, and an integrated bite block and cuff pressure indicator. It comes in three available sizes: #3 (30-50 kg), #4 (50-70 kg), and #5 (70-100 kg).

This device has been reported to have a high airway insertion success rate and a high first-attempt endoscopy success rate in patients with low risk of pulmonary aspiration. Observational studies have suggested that the LMA Gastro may be a safe alternative to tubeless anesthesia in patients undergoing ERCP, though some were limited by small sample size and non-randomized design. Retrospective analyses have demonstrated high success rates of ERCP completion with well-maintained ventilation and minimal intraoperative and postoperative adverse events. However, confounding factors in patient selection and the absence of randomized controlled comparisons with conventional airway techniques remain limitations.