Red plug: An alternative to the blocked ProSeal™ laryngeal mask airway inflation valve.

Sir,

The ProSeal™ LMA (ProSeal™ laryngeal mask airway - PLMA) is expensive and has a shorter life span than the classic LMA (cLMA).[1] The inflation valve of the PLMA is similar to that of the cLMA, and intubating LMA. It has a white polypropylene core and a stainless steel spring.[2]

We report the successful exchange of seven blocked non-functioning inflation valves with the functioning valves of discarded cLMA/PLMA. The repaired PLMAs were subjected to the tests recommended by the manufacturer before autoclaving and subsequently before use.[23]

Successful replacement of damaged cLMA inflation valves and repair of PLMA inflation line using functioning valves or PVC inflation lines taken from various sources have been reported.[45]

On three occasions, when we failed to get a replacement, we bypassed the non-functioning inflation valve of the PLMA, by using the red plug [Figure 1] to inflate the cuff of the PLMA without any problem. The red plug is a vent device integrated into the inflation valve-pilot balloon assembly of the PLMA.[26] Till date, we have conducted 20 laparoscopic procedures using the red plug to inflate the PLMA cuff without compromising the safety of the patients.

Figure 1

ProSeal™ LMA with red plug (a) PLMA with red plug and inflation valve. (b) Damaged inflation valve unit. (c) Red plug in use (directly connected to cuff pressure monitor). (d) Red plug connected to CPM (cuff pressure monitor) with an extension line

Failure to inflate the cuff, secondary to obstruction of the pilot balloon may be due to mechanical blockage (chemical residue, damage to valve by chemical agents used during cleaning or sterilisation, moisture or aging of the valve).[72] The manufacturer recommends discarding reusable LMAs after a maximum of 40 uses or when these devices fail the pre-use check tests. In many institutions, their use may extend beyond the recommended 40 uses or they may be used when the damaged part has been repaired and the LMA has fulfilled the pre-use check tests.[85]

Encouraged by our experience, previous reports,[45] failure of the manufacturer to replace damaged inflation valves and the high cost of the reusable LMAs, we now retain functioning inflation valves of LMAs slated for condemnation.