A laryngeal mask airway, widely known as an LMA, is a supraglottic airway device that sits over the entrance to the windpipe rather than passing through it. Invented in 1981 by anesthesiologist Archie Brain at the London Hospital, it was designed to bridge the gap between the traditional face mask and the endotracheal tube, offering hands-free ventilation without the stress of inserting a tube directly into the trachea.1PubMed. Laryngeal mask airway: an alternative for the difficult airway Since then, the LMA has become one of the most commonly used airway management tools in anesthesia, with multiple generations and variants now available for everything from routine day surgery to emergency resuscitation.
How an LMA Works
The device consists of a soft, inflatable cuff shaped roughly like an elliptical bowl, connected to a tube that protrudes from the mouth. Once inserted, the cuff forms a low-pressure seal around the laryngeal inlet, the opening that leads to the vocal cords and trachea. Air flows through the tube, past the seal, and into the lungs without anything actually entering the trachea itself. This is a fundamentally different approach from an endotracheal tube, which passes between the vocal cords and sits inside the trachea.
Insertion is relatively straightforward: the deflated cuff is guided along the hard palate, following the natural curve of the throat, until it settles into position over the larynx. The cuff is then inflated to create the seal. In skilled hands, the whole process takes seconds. A study comparing the i-gel (a cuffless supraglottic device) with the LMA Classic found that mean insertion time for the i-gel was about 16 seconds and for the Classic about 26 seconds, both well under a minute.2PubMed Central. Comparison of i-gelâ„¢ and laryngeal mask airway Classicâ„¢ in terms of ease of insertion and hemodynamic response: A randomized observational study Correct positioning matters, though. When assessed with a fiberoptic camera, blind insertion achieved an ideal position in about 42% of cases, while direct visual placement pushed that to over 90%.3Elsevier / Journal of Oral and Maxillofacial Surgery. Fiberoptic assessment of laryngeal mask airway placement: blind insertion versus direct visual epiglottoscopy In practice, most clinicians rely on clinical signs like adequate tidal volumes and lack of audible leak rather than fiberoptic confirmation for every case.
First-Generation and Second-Generation Devices
The original LMA Classic, the first-generation device, was a simple airway tube with an inflatable cuff. It worked well for spontaneous breathing and light positive-pressure ventilation, but it had limitations: the seal pressure was modest, and there was no way to decompress the stomach if gastric contents came up. Brain hoped the device would provide a safer alternative to complex intubation, especially in emergencies, and the Classic largely delivered on that promise for routine cases.4PubMed. Archie Brain: celebrating 30 years of development in laryngeal mask airways
Second-generation LMAs added two key features: a higher sealing pressure and a built-in gastric drainage channel. The higher seal pressure means the device can handle positive-pressure ventilation more reliably, which is important during controlled mechanical ventilation. The gastric channel allows a tube to be passed into the stomach to vent gas or drain fluid, reducing the risk of regurgitation reaching the lungs.5Scientific Reports. Second generation laryngeal mask airway during laparoscopic living liver donor hepatectomy: a randomized controlled trial Devices like the LMA ProSeal, LMA Supreme, and i-gel all fall into this second-generation category, each with slightly different design trade-offs.
The ProSeal tends to achieve the highest oropharyngeal leak pressures among these devices, often measured around 25 to 33 cm Hâ‚‚O depending on the study, but it takes a bit longer to insert.6PubMed Central. A comparative evaluation of ProSeal laryngeal mask airway, I-gel and Supreme laryngeal mask airway in adult patients undergoing elective surgery: A randomised trial The Supreme, being a single-use device with a rigid curved shape, slides in faster and still provides a clinically acceptable seal.7PubMed Central. Comparative Study of Two Laryngeal Mask Airways: Proseal Laryngeal Mask Airway and Supreme Laryngeal Mask Airway in Anesthetized Paralyzed Adults Undergoing Elective Surgery The i-gel uses a thermoplastic elastomer instead of an inflatable cuff, which means there is no cuff to inflate or overinflate. It tends to insert the fastest of the group.8PubMed Central. I-gel versus laryngeal mask airway-Proseal: Comparison of two supraglottic airway devices in short surgical procedures In a crossover trial comparing the i-gel to the LMA-Unique, leak pressures were similar and both devices were inserted on the first attempt in nearly all patients.9British Journal of Anaesthesia. Randomized crossover comparison between the i-gel and the LMA-Unique in anaesthetized, paralysed adults
When LMAs Are Used
The bread and butter of LMA use is elective surgery where the patient is fasted, positioned supine, and undergoing a relatively short procedure. Ambulatory (day) surgery is a perfect example: the patient comes in, gets a general anesthetic, has a procedure lasting an hour or two, and goes home the same day. The LMA Supreme has been described as safe and easy to use in exactly this setting.10European Journal of Anaesthesiology. Safety and efficacy of laryngeal mask airway Supreme versus laryngeal mask airway ProSeal: a randomized controlled trial But the device’s territory has expanded well beyond short, straightforward cases.
Second-generation devices have pushed into laparoscopic surgery, where the abdomen is inflated with gas and intra-abdominal pressure rises. A review of LMA use in laparoscopic cholecystectomy (gallbladder removal) found that devices with a drain channel achieved adequate ventilation, with very low rates of regurgitation and aspiration.11PubMed Central. Role of laryngeal mask airway in laparoscopic cholecystectomy A recent case series even demonstrated successful use of the LMA Protector in moderately obese patients undergoing laparoscopic cholecystectomy, with good seal pressures and gastric drainage throughout.12PubMed. Laryngeal Mask Airway Protectorâ„¢ in obese patients for laparoscopic cholecystectomies: A case series These are settings that would have been considered off-limits for the original Classic device.
Cesarean section under general anesthesia is another area where LMAs have been tested, since aspiration risk has historically been the main concern in obstetric airways. A randomized trial comparing the Supreme LMA to endotracheal intubation during cesarean delivery found similar ventilation parameters and maternal and fetal outcomes, with no aspiration in either group.13PubMed Central. Comparison of Supreme laryngeal mask airway versus endotracheal intubation for airway management during general anesthesia for cesarean section: a randomized controlled trial This is still a single trial, and most guidelines continue to recommend endotracheal intubation as the default for cesarean sections, but the result suggests that the safety gap may be narrower than traditionally assumed.
Sore Throat and Minor Complications
One of the practical advantages patients notice most is a lower rate of postoperative sore throat compared to endotracheal intubation. In one randomized study, about 36% of LMA patients reported a sore throat at 12 hours versus 61% of intubated patients.14PubMed Central. A randomized control study comparing the pharyngolaryngeal morbidity of laryngeal mask airway versus endotracheal tube A trial in patients undergoing minimally invasive esophagectomy (a major operation) found that sore throat at two hours was 10% in the LMA group and 27% in the endotracheal tube group, with lower pain scores in the LMA group on the first postoperative day as well.15Scientific Reports. Efficacy of laryngeal mask airway versus endotracheal tube during total minimally invasive oesophagectomy: a randomized controlled trial Related symptoms like hoarseness, cough, and difficulty swallowing also tend to be less common with an LMA.16PubMed Central. A prospective study on the incidence of sore throat after use of laryngeal mask airway during general anesthesia
That said, LMAs are not free of throat complications. One study found that LMA patients actually had more persistent mild sore throat at 24 and 36 hours than the intubated group, suggesting that LMA-related irritation can be slower to resolve in some individuals.17PubMed Central. A randomized control study comparing the pharyngolaryngeal morbidity of laryngeal mask airway versus endotracheal tube The mechanism is different: an endotracheal tube irritates the trachea and vocal cords directly, while an LMA exerts pressure against the pharyngeal and perilaryngeal tissues. Nerve injuries from that pressure are rare but documented. A systematic review of cranial nerve injuries from supraglottic devices found that the injuries typically result from pressure on nerves in the throat, often linked to an oversized device, an overinflated cuff, or poor positioning. Injuries to nerves other than the recurrent laryngeal nerve were generally mild and resolved on their own.18PubMed. Cranial nerve injuries with supraglottic airway devices: a systematic review of published case reports and series There is even a case report of numbness in the lower jaw after an LMA, traced to excessive cuff inflation compressing the inferior alveolar nerve.19PubMed Central. Inferior alveolar nerve injury with laryngeal mask airway: a case report
Aspiration Risk
The concern that kept the LMA from being used more broadly for decades is pulmonary aspiration: stomach contents entering the lungs. Because the LMA sits above the larynx rather than sealing the trachea from above, the theoretical risk seemed obvious. The evidence, though, paints a more reassuring picture for appropriately selected patients. A large analysis covering over 65,000 procedures with positive-pressure ventilation found three cases of aspiration with the LMA (out of about 35,600 procedures) and seven with the endotracheal tube (out of about 30,000 procedures), with no aspiration-related deaths in either group. The adjusted odds ratio was essentially 1, meaning no meaningful difference in risk between the two devices in this population.20PubMed. Risk of pulmonary aspiration with laryngeal mask airway and tracheal tube: analysis on 65 712 procedures with positive pressure ventilation The key qualifier there is “in this selected population.” The patients in that study had been screened and those at high aspiration risk were excluded from the LMA group. The data does not mean you can use an LMA on a patient with a full stomach and expect the same safety profile.
The LMA as a Rescue and Intubation Tool
Brain’s original hope was that his device would serve as a fallback when face mask ventilation or intubation proved difficult, and this turned out to be one of the LMA’s most important roles. When an anesthesiologist or emergency physician cannot see the vocal cords with a laryngoscope, sliding in an LMA can restore ventilation within seconds and buy time. The device now occupies a central place in difficult airway algorithms worldwide.
A specialized version called the intubating LMA (ILMA, or LMA Fastrach) takes this further. It is built with a rigid handle and a wide-bore tube so that an endotracheal tube can be blindly threaded through it and into the trachea. A prospective evaluation of the ILMA in out-of-hospital emergencies, including patients with difficult laryngoscopy, limited head access, and pharyngeal trauma, supported its value as a rescue device for field use by trained providers.21British Journal of Anaesthesia. Intubating laryngeal mask airway for difficult out-of-hospital airway management: a prospective evaluation In a clinical trial comparing the LMA CTrach (which has a built-in camera) to the Fastrach, first-attempt intubation success was about 93% with the CTrach and 68% with the Fastrach, though both reached nearly 100% within three attempts.22Anesthesiology. Success of Tracheal Intubation with Intubating Laryngeal Mask Airways The i-gel has also been studied as an intubation conduit, with fiberoptic-guided tube placement succeeding in over 96% of patients on the first attempt.23PubMed Central. Comparative study of fiber-optic guided tracheal intubation through intubating laryngeal mask airway LMA Fastrachâ„¢ and i-gel in adult paralyzed patients
In cardiac arrest, the picture is more complicated. An indirect meta-analysis comparing bag-valve-mask, LMA, and endotracheal intubation for out-of-hospital cardiac arrest found that LMA and bag-valve-mask had similar rates of return of spontaneous circulation (about 23–24%) and similar survival to hospital discharge (about 4–6%). Endotracheal intubation outperformed the LMA across all survival endpoints in the pooled data.24PubMed Central. Comparing the efficacy of bag-valve mask, endotracheal intubation, and laryngeal mask airway for subjects with out-of-hospital cardiac arrest: an indirect meta-analysis This comparison is complicated by selection bias: patients who received an endotracheal tube likely had more experienced airway providers or more favorable anatomy, which confounds the comparison. Still, the data suggests that while the LMA is a viable bridge device in cardiac arrest, definitive intubation may be preferable when skilled personnel are available.
What Makes an LMA Fail
Most LMA insertions succeed on the first try, but not all. A study of over 15,700 patients using the LMA Unique identified four independent risk factors for failure: surgical table rotation, male sex, poor dentition, and higher body mass index. When the device did fail, the consequences were not trivial. More than 60% of patients with a failed LMA experienced significant low oxygen levels, elevated carbon dioxide, or airway obstruction, and 42% had inadequate ventilation from a leak.25Anesthesiology. Predictors and Clinical Outcomes from Failed Laryngeal Mask Airway Unique: A Study of 15,795 Patients A separate study on the LMA Supreme found that age over 61, high body weight, very low BMI (under 20), and inserting the device without lubricating lidocaine gel all increased the chance of first-attempt failure.26PubMed Central. Predictive risk factors of failed laryngeal mask airway insertion at first attempt
Broadly, clinicians avoid LMAs when the risk of regurgitation is high (unfasted patients, severe gastroesophageal reflux, bowel obstruction), when very high airway pressures are needed (severe bronchospasm, morbid obesity in some settings), and when the surgical position makes maintaining the seal difficult (prone position, steep lateral tilt). These are guidelines rather than absolute rules, and experienced providers sometimes push the boundaries with second-generation devices in controlled environments.
Sizing in Children
LMA sizing has traditionally been based on body weight: pick a size from a manufacturer chart, insert it, and hope for the best. In pediatric patients, this method works reasonably well most of the time, but a recent randomized trial tested a different approach. Researchers used ultrasound to measure the distance between the hyoid bone and the chin (the hyomental distance) and used that measurement to select the LMA size. The ultrasound-guided group had a significantly higher first-attempt success rate: about 93% versus 70% with the standard weight-based method. Optimization scores were also better, meaning the device sat more symmetrically and aligned more accurately with the esophagus.27PubMed Central. Hyomental distance measured ultrasonography versus weight-based criteria for laryngeal mask size selection in children: a randomized controlled trial This is still a relatively new approach and not yet standard practice, but it highlights a real limitation of weight-based sizing: two children who weigh the same can have quite different throat anatomy.
Learning Curve
One reason the LMA became so popular so quickly is that it is far easier to learn than endotracheal intubation. Direct laryngoscopy requires practice to consistently visualize the vocal cords, especially in patients with difficult anatomy. LMA insertion, by contrast, follows a relatively forgiving anatomical pathway. A study comparing two intubating LMAs in novice operators found that insertion times for the i-gel averaged about 12 seconds on first training and remained under 15 seconds at a 90-day reassessment. The Aura-i, an inflatable-cuff device, took about 22 seconds initially and nearly 29 seconds at follow-up, with one participant failing to insert it at the second evaluation.28PubMed Central. Comparison of learning performance of 2 intubating laryngeal mask airways in novice The increase in time at the 90-day mark suggests that without regular practice, even a simple device loses some of its initial proficiency edge. Skills decay is worth factoring into training programs, particularly for providers who do not manage airways frequently.
Reusable vs. Disposable and the Sterilization Problem
The original LMA Classic was designed to be reusable, autoclaved up to 40 times per the manufacturer’s recommendation. In practice, devices often lasted longer: a bench study found that Classic LMAs survived an average of 133 simulated use-and-sterilization cycles before failing pre-use checks, while ProSeal devices averaged 82 cycles.29Anesthesia & Analgesia. The ProSealâ„¢ Has a Shorter Life-Span than the Classicâ„¢ Laryngeal Mask Airway Both exceeded the manufacturer’s 40-use recommendation, leading the researchers to suggest discarding devices when they fail the pre-use check rather than after a fixed number of uses.
However, reprocessing reusable LMAs is not as clean as it might seem. One study tested every reusable Classic and flexible LMA in a hospital after they went through the full cleaning-and-autoclaving cycle: enzymatic wash, machine wash at up to 85°C, drying, and autoclaving at 134°C. Over 90% of both Classic and flexible LMAs still had detectable protein residue on their surfaces.30PubMed. Routine cleaning and autoclaving does not remove protein deposits from reusable laryngeal mask devices A follow-up study confirmed that protein contamination increases with each reuse cycle, accumulating despite standard sterilization.31PubMed. Protein contamination of the Laryngeal Mask Airway and its relationship to re-use The clinical significance of these trace protein deposits remains debated. There has been no documented transmission of prion disease from an LMA, but the finding pushed many hospitals, particularly in the UK and parts of Europe, toward single-use devices.
That shift to disposable LMAs came with its own trade-off: environmental impact. A life cycle assessment at Yale New Haven Hospital found that reusable LMAs had a more favorable environmental profile than disposable ones, with the main impact of disposables coming from polymer production, packaging, and waste management, while reusable device impacts were dominated by the washing and sterilization process.32PubMed. Comparative life cycle assessment of disposable and reusable laryngeal mask airways A more recent Swedish analysis put numbers on the carbon footprint: a reusable laryngeal mask produced about 141 grams of COâ‚‚ equivalent per use, compared to roughly 600 to 1,000 grams for single-use alternatives.33PubMed Central. Climate Impact of Laryngeal Masks: Climate and Other Environmental Impacts of Reusable and Single-Use Laryngeal Masks in Sweden When you multiply those per-use differences by the millions of anesthetics given annually worldwide, the aggregate environmental cost of the disposable trend is substantial.
LMAs Beyond Human Medicine
Supraglottic airway devices have also found a niche in veterinary anesthesia, particularly for cats, whose small airways and reactive laryngeal anatomy make endotracheal intubation genuinely tricky. A purpose-built device called the V-gel has been designed to match feline pharyngeal anatomy. A study evaluating the V-gel across different ventilatory modes in anesthetized cats enrolled 52 animals, obtaining usable data from 47. Two cats were withdrawn due to regurgitation with severe aspiration, a reminder that the aspiration question is not unique to humans and that supraglottic devices have similar limitations across species.34PubMed Central. Evaluation of the V-gel Advanced Supraglottic Airway Device Across Different Ventilatory Modes in Anaesthetised Cats Rabbit-specific versions also exist, reflecting how broadly the LMA concept has spread beyond its original operating-room context.