Anaes · Airway management
Supraglottic airway devices (LMA and SGAD): generations, applications and the difficult-airway rescue
Also known as Laryngeal mask airway · LMA · Classic LMA · ProSeal LMA · LMA Supreme · i-gel · Intubating LMA · Fastrach · Second-generation supraglottic airway device · SGAD
Supraglottic airway devices (SGADs) sit above the glottis and provide a hands-free airway without tracheal intubation, and they are the most frequently examined single piece of airway equipment because they straddle routine practice and the rescue algorithm. The framework rests on four ideas: the device forms a seal around the laryngeal inlet and leaves the hands free, but it is not a definitive airway; the first generation (the classic LMA of Brain, 1988) has an inflatable cuff, a low seal pressure around 20 cm H2O, and no gastric drainage channel; the second generation (ProSeal LMA, LMA Supreme, i-gel) raises the seal pressure to 30 to 40 cm H2O and adds a gastric drainage channel that materially improves aspiration protection; and the devices are the DAS 2015 Plan B rescue after failed intubation, a bridge to intubation through the Fastrach, and a first-line option in CPR, prehospital and paediatric anaesthesia. Anchored to contemporary evidence on gastric-tube placement through the second-generation drainage channel, the non-inflatable visual laryngeal mask, the sevoflurane concentration for i-gel insertion in children, and the difficult airway of spinal muscular atrophy and the physiological emergency airway.
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- A supraglottic airway is NOT a definitive airway. It does not isolate the trachea from the oesophagus, and it does not fully protect against aspiration — most importantly in the first-generation device, which has no gastric drainage channel. Reserve the elective use for fasted patients at low aspiration risk, and prefer a second-generation device with a gastric channel whenever the risk is borderline.
- The classic LMA cuff seal pressure is only about 20 cm H2O. In the patient with low pulmonary compliance or high airway resistance — obesity, bronchospasm, the head-down laparoscopic position — peak airway pressures exceed the seal and the device vents, leak, and fails to ventilate. A second-generation device (seal pressure 30 to 40 cm H2O) or an endotracheal tube is required.
- Displacement is the silent failure of the supraglottic airway. The device can rotate, migrate, or be knocked out during positioning, surgery, or transfer, and the leak or the gastric insufflation that follows is easily missed without continuous capnography. Continuous waveform capnography is mandatory for every case managed with a supraglottic device.
- In the unanticipated failed intubation, the SGAD is the DAS 2015 Plan B RESCUE. If oxygenation is inadequate after a best-attempt SGAD placement, do not persist — proceed to Plan C (cannula or surgical cricothyroidotomy, the CICO rescue). Oxygenation that is adequate after the SGAD is a reason to stop, wake the patient, and not to persist with repeated attempts at intubation.
- High aspiration risk — the full stomach, obesity, pregnancy, gastro-oesophageal reflux disease, ileus, and the upper-airway obstruction or bowel obstruction — is a relative contraindication to a first-generation device and an indication for a rapid sequence induction with an endotracheal tube. The second-generation gastric channel partially mitigates but does not abolish the risk.
Meet the patient
A fit, fasted 45-year-old arrives for a day-case knee arthroscopy — short case, spontaneous ventilation, no muscle relaxant needed. You plan a second-generation supraglottic airway so your hands are free for the surgical positioning, and the patient wakes with less sore throat than a tube would leave.[2]
The question every supraglottic-airway decision answers is threefold: can it seal at the airway pressure this lung demands, does it protect against aspiration, and is it the right tool if the airway turns difficult? Hold those three, and the whole device family sorts itself cleanly.[2]
References6ShowHide
- [1]Yin X, et al. Gastric tube placement through the drainage channel of second-generation supraglottic airway devices: a systematic review with evidence mapping Front Surg, 2026.PMID 42344572
- [2]Migliorelli S, et al. Clinical Evaluation of a Non-inflatable Visual Laryngeal Mask Airway: A Prospective Service Assessment in Elective and Difficult Airway Management Cureus, 2026.PMID 42291977
- [3]Gan Z, et al. The Median Effective Concentration of Sevoflurane for I-Gel Laryngeal Mask Insertion in Unpremedicated Children Aged 1-10 Years: A Prospective Concentration-Finding Study Pediatr Discov, 2026.PMID 42021953
- [4]Black KM, et al. Anesthesia Care, Complications, and Airway Management for Patients With Spinal Muscular Atrophy: A Retrospective Chart Review From a Quaternary Children's Hospital Anesth Analg, 2026.PMID 42363899
- [5]Ghaffar S, et al. Physiological difficult airway management in the emergency department J Pak Med Assoc, 2026.PMID 42363338
- [6]Schramm D, et al. Bronchoscopic and interventional management of tracheobronchomalacia in children with bronchopulmonary dysplasia: a review of evidence Paediatr Respir Rev, 2026.PMID 42364941