Supplementary cleaning does not remove protein deposits from re-usable laryngeal mask devices

To test the hypothesis that supplementary cleaning facilitates removal of protein deposits from the laryngeal mask airway (LMA).

Twenty previously used Classic) and Flexible LMAs were hand washed, machine washed, dried, autoclaved and then randomly allocated into four groups for supplementary cleaning. In Group A, the dorsal surface was immersed in water and the surface scrubbed with a high-speed rotating brush. In Group B, the dorsal surface was immersed in a plaque removing solution. In Group C, the dorsal surface was immersed in a protein removing solution. In Group D (controls), the dorsal surface was immersed in water. Before and after supplementary cleaning the LMAs were immersed in a protein staining solution, rinsed and a high-resolution digital image taken of the dorsal surface. The location and severity of staining were scored by two observers blinded to group assignment.

Staining was similar before and after supplementary cleaning for all groups. Mild, moderate and severe staining occurred in 31%, 7% and 2% of zones respectively; 60% were unstained. Staining was less common on the cuff than on the backplate and distal tube (both: P < 0.00001). Staining was less common on the backplate than on the distal tube (P = 0.001). Staining was always present on the mid-portion of the backplate or distal tube.

Supplementary cleaning using a rotating brush, plaque or protein removing solution does not facilitate removal of protein deposits from re-usable LMAs; however, the infectious risk associated with the protein deposits remains to be determined.