Arguments against

The cLMA has been described as offering no protection against aspiration.

Some authors argue that by sitting in the lower pharynx, the cLMA can act like a bolus of food, stimulating a 'swallowing reflex' and therefore leading to relaxation of the lower oesophageal sphincter.

Others argue that the cLMA may channel regurgitant material into the larynx.

One study using a swallowed dye as a marker reported an incidence of aspiration with the cLMA of 25%.

Arguments in favour

To counter the arguments against, recent work shows the following arguments for the cLMA.

• A carefully performed cadaver study, involving injection of fluid up the oesophagus, demonstrated that the cLMA provided approximately 3-4 times the protection against aspiration that the native airway provides (the ProSeal LMA was even better)
• More recent manometry studies show no effect of the presence of the cLMA (or the bulkier ProSeal LMA), on upper or low oesophageal sphincter pressure
• Subtraction MRI data suggests channeling of liquid into the larynx with the cLMA is highly unlikely (but perhaps more likely with some single-use laryngeal masks)
• The considerable safety record of the cLMA is reassuring. The incidence of aspiration with the cLMA in elective patients is very low at 1 in 4000 - 11 000