Strength of disposable laryngoscopes.

Abstract

The concern regarding transmission of prion-related disease and other infections has brought about a huge drive to develop and utilise single use airway equipment. However, we are worried that the materials and standards to which these instruments are made will not be of the same quality as their reusable counterparts. A recent proposal to the British Standards Institute (BSI), who are developing a standard for disposable laryngoscope blades, suggested that a disposable blade should be able to withstand a primary axis maximal force of approximately 150 N (15 kg) (A.R. Wilkes, personal communication). This was to provide a margin of safety against breakage of the blade when compared with the maximal force of 90 N found when intubating a manikin [1]. It would follow that these proposals would also be applied to completely disposable laryngoscopes. However, it has also been shown that the force applied to a laryngoscope blade varies not only with the material of manufacture [1] but also with the practitioner [2]. Fifteen experienced anaesthetists (seven consultants, eight specialist registrars) used a laryngoscope handle on a stationary object at approximate intubating height and position. They were asked to use the maximum force that they would be comfortable applying to a patient under unexpected difficult intubation conditions. The applied force was measured using calibrated bathroom scales that the participants were unable to see. The results were varied over a range of 70–350 N, and a mean of 151 N. This simple observation shows that the proposed standards for the disposable equipment would not have been adequate for seven of our 15 participants. It also supports the findings of previous work relating to the inconsistency of forces applied by different anaesthetists [2]. We would argue that the proposals put forward to the BSI regarding disposable laryngoscope blades are inadequate. Any disposable equipment used should be shown to be at least as reliable as its predecessor before implementation is authorised.