Martin J Wolfe
MB BS FRCA
Medical Specialist Group
The laryngeal mask airway (LMA) became an overnight success in anaesthetic practice after its introduction in 1989 owing to ease of insertion, convenience of airway maintenance and reduced requirement for tracheal intubation in many patients.
Although many manufacturers tried to develop the original LMA concept with minor design alterations, it was not until the development of the Intersurgical i-gel supraglottal airway earlier this year that a major improvement on the original concept arrived.
Superficially similar in appearance to other LMA variants, the i-gel can be immediately recognised by its soft gel cuff, which, unlike other LMAs, requires no inflation. This new feature allows quicker, easier and gentler insertion, with the soft gel pad adapting its contours to fit the shape of the individual pharynx. Absence of an inflatable cuff makes insertion invariably a “one-person technique”, allowing the anaesthetic assistant the freedom to perform other essential duties.
An integral design feature of the i-gel is the gastric vent, which aids “confirmation” that the device is correctly positioned. If the stomach inflates with gases during the initial facemask inflation of the patient’s lungs before inserting the device, the gas will be immediately released via the gastric port on successful insertion of the i-gel. Pharyngeal secretions are readily aspirated by the passage of a suction catheter down the port, and gastric regurgitation is similarly easily recognisable by fluid ejection up the port.
The gastric port offers a major design advantage over all other devices (with the exception of the Intavent Proseal, which is much harder to insert and a costlier product). Use of the i-gel appears to reduce the risk of raised intragastric pressure, which remains a serious concern associated with use of conventional LMAs in patients particularly at risk of gastric regurgitation.
The i-gel’s main ventilation tube is elliptical in cross-section, whereas other conventional LMAs are round. This greatly improves stability after correct placement in the oropharynx and minimises the amount of rotation of the device, making it often unnecessary to use conventional fixation with tape or adhesive strapping.
For many years, tracheal intubation has been the gold standard for airway management in cardiopulmonary resuscitation (CPR). Some clinicians have encouraged use of the LMA as an acceptable and speedier alternative to tracheal intubation, but for many this has seemed neither a safe nor a reliable option.
The arrival of the i-gel at about the same time as the introduction of revised European Resuscitation Council guidelines may well change this. Passing a tracheal tube is time-consuming, especially for paramedics and nurses. The current priority in CPR has changed to cardiac compression over airway ventilation, so quick and reliable provision of an airway in the early stages of CPR without compromising continuing cardiac compression seems desirable. It is feasible that there may be a change to the routine use of the i-gel by paramedics, nurses and even clinicians, who may well find that the expertise needed for successful i-gel insertion is gained quickly, making the latter a faster and more reliable technique than tracheal intubation.
As with the introduction of the original LMA into clinical practice nearly 20 years ago, the advent of the Intersurgical i-gel is seen by many clinicians as a further milestone in the development of safe, reliable and easier airway management in the unconscious patient.