A supraglottic airway (SGA) is a medical device used to maintain an open pathway for air to reach a patient’s lungs during medical procedures or emergencies. Unlike techniques that require a tube to be threaded into the windpipe, the SGA is secured above the vocal cords to establish effective ventilation. This allows oxygen and anesthetic gases to be delivered efficiently without complex maneuvers or deep insertion into the respiratory system. The primary goal of using an SGA is to rapidly and reliably support a patient’s breathing function when they cannot ventilate adequately on their own.
Basic Function and Placement
The function of a supraglottic airway is centered on creating a seal within the pharynx, the shared area behind the nose and mouth, specifically around the larynx (voice box). The device is inserted through the mouth and positioned so that its tip rests just above the vocal cords (glottis). This superior positioning keeps the device entirely external to the trachea.
Once in place, the SGA’s mask component or cuff molds itself to the peri-laryngeal structures, creating a low-pressure seal. This seal allows for positive pressure ventilation, ensuring air is pushed into the lungs without escaping or causing gastric inflation by entering the esophagus. The device is designed for blind placement, relying on anatomical guidance, which contributes to the speed and ease of insertion.
This technique differs fundamentally from endotracheal intubation (ETI), which involves passing a tube directly between the vocal cords and into the trachea. The SGA bypasses the narrowest part of the airway and avoids the need for direct visualization of the vocal cords during placement. The SGA provides a stable and secure conduit for air exchange that is relatively non-invasive.
Common Types of Supraglottic Airways
The most recognizable and foundational design within this device category is the Laryngeal Mask Airway (LMA), first introduced in the early 1980s. The LMA is typically a first-generation device featuring an inflatable cuff surrounding a central tube. This cuff conforms to the peri-laryngeal structures once inflated, achieving the necessary seal while minimizing pressure trauma to the mucosa.
Building upon this concept, second and third-generation devices have emerged with specialized features to improve ventilation and reduce the risk of aspiration. Devices like the i-gel utilize a non-inflatable, thermoplastic elastomer material that is anatomically contoured to the pharyngeal and laryngeal anatomy. This design simplifies insertion by eliminating the need for cuff inflation and may decrease the incidence of subsequent sore throat.
Another specialized design is the Laryngeal Tube (LT), such as the King LT, which features two separate inflatable cuffs. One cuff seals the lower pharynx, and the other seals the upper esophagus. Many second and third-generation SGAs, including the LMA-Supreme and the i-gel, incorporate integrated features:
- An integrated channel specifically designed to allow a gastric tube to be passed into the stomach.
- Improved ventilation capabilities.
- Reduced risk of aspiration.
- The ability to achieve a higher pressure pharyngeal seal.
The choice among these varied devices is determined by the specific requirements of the patient and the clinical environment.
Clinical Applications and Settings
Supraglottic airways find extensive utility across various medical settings, broadly categorized into planned procedures under anesthesia and urgent airway management in emergencies. In the operating room, SGAs are routinely used for general anesthesia during surgeries that are relatively short or those that do not require deep muscle paralysis. Anesthesiologists appreciate the ease of placement for routine cases, allowing for a quicker transition into the maintenance phase of anesthesia.
In pre-hospital care and emergency medicine, SGAs are highly valued for their role in cardiopulmonary resuscitation (CPR) and trauma management. When a patient requires immediate ventilatory support, the rapid insertion and high success rate make it a superior option over the more time-consuming process of endotracheal intubation. SGAs are often designated as the primary device for airway control in cardiac arrest protocols due to their efficiency and ease of use by emergency medical services (EMS) clinicians.
Furthermore, SGAs serve a significant function as a rescue device when a traditional attempt at tracheal intubation is difficult or has failed. This is particularly true in a “cannot intubate, cannot ventilate” scenario, where the SGA provides a temporary but reliable means of oxygenation. The device can also be used as a conduit to assist with fiberoptic bronchoscope-guided intubation, allowing medical professionals time to secure a definitive airway.
Advantages Over Endotracheal Intubation
A primary benefit of the SGA approach is the significantly reduced time and lower skill level required for successful insertion compared to an endotracheal tube (ETT). The technique relies on anatomical landmarks rather than direct visualization of the vocal cords, which translates to a higher first-pass success rate in many emergency settings. The intervention time for advanced airway placement is significantly shorter for SGAs compared to ETI, especially in out-of-hospital cardiac arrest.
The less invasive nature of the placement is another considerable advantage, as the device does not need to pass through the vocal cords. This reduces the risk of trauma to the delicate laryngeal structures, which can sometimes be irritated or injured during ETT placement. This less stimulating insertion process also contributes to greater hemodynamic stability in the patient.
The placement of an SGA typically causes less stimulation of the patient’s reflexes, reducing the likelihood of a sudden spike in heart rate or blood pressure immediately following airway insertion. While SGAs offer numerous benefits, they do not provide the same high level of protection against the aspiration of stomach contents into the lungs as a cuffed ETT. Therefore, they are generally not recommended for patients with a known full stomach or other high risk factors for regurgitation.