Only with an optimal position of the supraglottic airway in situ, valid conclusions can be drawn about oropharyngeal airway pressure.

Sir,

We were interested by the recent publication of Banerjee et al. in the Indian Journal of Anaesthesia on the comparison of the ProSeal and the i-gel supraglottic airway devices (SADs) in different head-and-neck positions in anaesthetised paralysed children.[1] The authors did not detect a significant difference in the oropharyngeal leak pressures, fibreoptic gradings and ventilation scores in three positions (neutral and maximum flexion/extension).

Although the oropharyngeal leak pressure is the golden standard in SADs, no conclusion can be drawn if the first one does not ascertain the correct position of the device in the hypopharynx. Fibreoptic evaluation of the position of the airway is the norm and used by the authors. However, it is clear from their results of the fibreoptic grading of the two SADs in three different head-and-neck positions that the overall majority of the airway devices was not in the optimal position, defined as: epiglottis sitting on the outside of the cuff, with an unobstructed view of the glottis, showing the posterior side of the epiglottis, but not the tip of the epiglottis.[234] The authors showed less-than-optimal positions, i.e., with the tip of the epiglottis sitting in the bowl of the device, and a complete view of the vocal cords (suboptimal), or a partially covered view of the vocal cords, showing the anterior side of the down-folded epiglottis (impaired), or a completely covered view of the entrance to the trachea due to the complete down folding of the epiglottis, which potentially may obstruct the airway, cause trauma to the region and impair gas exchange (failed). More than 75% of all three head-and-neck positions with the two SADs studied by the authors resulted in a less-than-optimal positioned airway as graded by fibreoptic view [Table 2 of the authors' study].[1]

We would like to encourage the authors to repeat their study with SADs sitting in an optimal anatomical position in the hypopharynx using a vision-guided insertion technique with a videolaryngoscope and determine whether different head-and-neck positions result in changes in the oropharyngeal leak pressures and ventilation. Recently, we advocated using a vision-guided insertion technique of SADs based on a 'detect-correct-as-you-go technique' using standardised jaw lift manoeuvres to immediately correct any malpositioned airway device.[23]

Furthermore, it would be wise to measure the intracuff pressure after insertion of the cuffed SAD, to make sure that the seal around the entrance to the glottis is 40–60 cmH2O, avoiding under- and over-pressure, as the latter two may influence the oropharyngeal leak pressure.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.