High concentration potassium permanganate eliminates protein and particle contamination of the reusable Classic^™ laryngeal mask airway

Abstract

Summary In this three‐stage study, we test the hypothesis that supplementary cleaning with potassium permanganate ≥4 mg.l−1 eliminates protein and particle contamination from the reusable Classic™ laryngeal mask airway. The first stage involved supplementary cleaning of 70 1 × 1 cm segments from deliberately contaminated laryngeal mask airways using potassium permanganate at 0, 2, 4, 8, 16, 32 and 64 mg.l−1 and testing for protein staining. This showed that the lowest concentration required to eliminate protein contamination was 8 mg.l−1. The second stage involved supplementary cleaning of 50 used laryngeal mask airways with either potassium permanganate 8 mg.l−1 or saline and testing for protein staining. This showed that protein contamination was lower in the potassium permanganate group (p < 0.00001): all laryngeal mask airways in the control group and none in the potassium permanganate group were contaminated. The third stage involved scanning electron microscopic examination of 1 × 1 cm segments from three laryngeal mask airways used in the control group, three from the potassium permanganate group, plus three brand new laryngeal mask airways. The mean density of ≥1 μm surface particles was lower in the potassium permanganate 8 mg.l−1 than the control group (21 vs. 121 .cm−2, p < 0.0001) and was similar to brand new laryngeal mask airways (24 .cm−2). We conclude that supplementary cleaning with potassium permanganate 8 mg.l−1 eliminates protein deposits from reusable laryngeal mask airways and reduces particle contamination to similar levels to brand new laryngeal mask airways.

Coming round to recycling

“…It remains unclear whether the risk of infection is real or perceived, 16 particularly with regard to prion transmission, 17 and whether what is required is more effective sterilisation procedures rather than disposable equipment. 18 Reusing single use devices has been shown to save money, provided no adverse events occur, 19 and would also reduce packaging and clinical waste. However, there could be legal ramifications 20 : the Medicines and Healthcare Products Regulatory Agency has stated that "Anyone who reprocesses or reuses a device intended by the manufacturer for use on a single occasion, bears full responsibility for its safety and effectiveness," exposing doctors and hospitals to civil liability.…”

The effect of high concentration potassium permanganate on protein contamination from metallic and synthetic rubber airway equipment

“…Seven supplementary cleaning techniques have been described for removal of protein contamination from silicone‐based airway devices. Three are ineffective (additional machine washing [7], repeat autoclaving [8], and staining as a guide to cleaning [9]); three are moderately effective (systematic cleaning, scrubbing and ultrasonic cleaning [9]); and one is highly effective [10, 11]. Our group showed that potassium permanganate 2 mg.l −1 reduces the number of protein‐contaminated devices from 100 to 20%[10] and that the 8 mg.l −1 solution eliminates protein contamination and reduces particle load down to levels similar to brand new devices [11].…”

“…Repeat washing [7] and repeat autoclaving [8] do not reduce protein contamination, but systematic scrubbing [9], ultrasonic cleaning [9] and immersion potassium permanganate 2 mg.l −1 [10] leads to more effective removal. In addition, our group found that 8 mg.l −1 potassium permanganate eliminated protein and particle contamination from silicone re‐usable airway devices [11]. In this follow‐up study, we test the hypothesis that supplementary cleaning using potassium permanganate 8 mg.l −1 eliminates protein deposits from metallic and synthetic rubber airway equipment.…”

Botox injections and monitoring neuromuscular blockade

“…This case has changed our practice in two ways: we now use the ulnar nerve whenever possible to monitor neuromuscular function, and we routinely ask youthfullooking patients of either sex whether they have had recent Botox injections. In the above article [1], the incorrect spelling was given for the first author. The correct spelling is now detailed in the reference.…”