Multiple airways devices exist that are used to help oxygenate and ventilate a patient in an emergency or a controlled setting. One set of products is called supraglottic airways devices (SAD). Supraglottic airways sit above or around the glottic opening and do not go any further into the airway. SADs are devices that keep the upper airway clear for unobstructed ventilation.8 The laryngeal mask airway (LMA) is an example of a supraglottic airway and has been in use since 1981. The development of the LMA has been hailed as one of the most significant advances in airway management since the endotracheal (ET) tube.9 A great deal of literature exists that reports the successful use of the LMA as a primary airway device and as a conduit for intubation of the trachea.6 SADs are now used in a wide variety of clinical indications and their versatility and ease of use make them particularly valuable to caregivers practicing anesthesia, resuscitation, and intensive care.8
The LMA has many advantages over an ET tube in that LMAs are less invasive, decrease airway trauma, decrease neck mobility requirements, and have a reduced risk of laryngospasm and bronchospasm.3
There are varied types and designs of LMAs, developed and used for specific purposes. First-generation devices are simple airway tubes that do not have specific design characteristics aimed at reducing the risk of pulmonary aspiration of gastric contents.8 The LMA Classic was the first product used and has been in place since the early 1980s. The LMA Classic received wide recognition in a short time and has had a major impact on anesthesia practice and airway management2. Other variations include the Flexible, ProSeal, Supreme, and Fastrach models (all from Teleflex in Wayne, PA).
LMAs come in multiple sizes and the correct one is based on the patient’s weight. LMA insertion is usually accomplished using the classic technique, which involves placing a water-based lubricant on the posterior aspect and deflating the cuff. The practitioner inserts the LMA midline into the mouth with the posterior surface pressed flat against the palate of the mouth and then advances with the index finger along the palatopharyngeal curve.7 The LMA device can be aligned with anatomical landmarks such as the lips and mandible to ensure proper sizing and correct placement produces a leak-free seal against the glottis.10 Reports have indicated between an 88% and 95% success rate on the first attempt with an experienced provider.5
Second-generation SADs incorporate specific features to improve positive pressure ventilation (PPV) and reduce the risk of aspiration.8 Compared to original SAD designs, second generation SADs are designed to do the following:
Van Esch reported that second-generation supraglottic airway devices have been introduced, enabling a higher positive pressure, reducing the risk of aspiration, and lowering the risk on respiratory complications.
Some examples of second generation LMAs are the LMA ProSeal (PLMA) and LMA Supreme (Teleflex), i-gel (Intersurgical), and the AuraGain (Ambu).7 The King LTS-D (Ambu) is also a considered a second generation device and is traditionally used in the prehospital setting.
The early recognition of the value of the LMA in management of difficult airway situations has influenced the widespread acceptance of SAD technology in clinical practice.8
Use of the LMA does not exclude potential risks and complications. Many complications – from airway injury, bleeding, edema, aspiration of gastric contents, failed placement, and more – are still possible. Nerves at risk for insult due to LMA placement include the recurrent laryngeal nerve, hypoglossal nerve and lingual nerve.4 Potential factors responsible for lingual nerve injury include:
SADs continue to be an important mode of rescue ventilation in patients in whom mask ventilation or tracheal intubation is impossible.8 Despite these advances, specific concerns such as ventilatory failure, airway injury, and pulmonary aspiration of gastric contents remain, necessitating careful patient selection and appropriate techniques for the successful use of these devices.8