Supreme Laryngeal Mask Case Study

The Supreme laryngeal mask (SLMA), a second generation Laryngeal mask Airway (LMA) is a single use, latex free device with an anatomical curve. It has a gastric drain tube allowing access to gastric contents and a cuff which provides 2 seals, one at the oropharynx and the other at the upper end of the oesophagus, separating the respiratory from the digestive tract. Correct placement produces a leak-free seal against the glottis with the tip at the upper oesophageal sphincter.
Available in sizes 1 to 5, SLMA size selection is based on the actual body weight of a patient (size 3, 30-50 kg, size 4, 50-70kg, size5, 70-100kg). Maximum recommended cuff volumes are 20ml/30ml/45ml respectively and the cuff pressures should be ≤ 60 cm H₂O.
The average

In those with a suboptimal fit (n=107), the gastric tube could be easily passed in 92.5%. Even with a poor fit, the gastric tube could be passed easily in 13 of the 15 cases. This indicates a proper positioning of the SLMA at the upper end of the oesophagus despite the fit appearing suboptimal as per the criteria. In 10 (5.1%) patients the gastric tube could not be passed which indicates less than ideal positioning at the upper end of the oesophagus and the larynx with risk of aspiration of gastric contents negating the benefits of using a

The fixation tab was correctly positioned i.e., 1.5-2.5cm from the upper lip in only 49% of cases.
Despite the above disparity in the fit, the OT anesthetist perceived the ventilation to be adequate and continued with the existing supraglottic device in 86.7% cases. This suggests that anesthetists appear reluctant to change to an alternate LMA or airway device if the ventilation is perceived to be adequate despite the apparent suboptimal fit. The other reason could be the added cost to the patient per LMA.
In our study, though the median volume of air used for cuff inflation was 20 ml for size 3 SLMA and 30 ml for size 4, the volume ranged from 15-30 ml for size 3 and 20-30 ml for size 4 which is much higher than that recommended. This could possibly be explained by the fact that in 24 patients, a one size smaller SLMA was used. In 16 patients who weighed >70 Kg a size 4 SLMA was used instead of a size 5 which is not easily available. The cuff was therefore probably overinflated to minimize a leak. A study by C.Verghese and B.Ramaswamy 9 showed median volume of air for cuff inflation to 60 cm H₂O was 21.9