Search For A New Material
Following the realisation that a new material was needed, Brain looked at a number of options; polyvinyl chloride was too rigid and synthetic foam did not lend itself to re-use. Silicone prototypes looked promising as what was produced was an elipse with a flat central web which, if cut correctly, could be used to create an aperture bar to prevent the epiglottis falling into the distal aperture. The silicone prototype was also smooth and deflated into a wafer thin elipse, however, the silicone mask was unable to retain the desired bowl shape and it was no longer possible to make rapid adjustments to the design. The silicone Dunlop prototype was superior to the Goldman prototype, one of Brains first prototypes created from the cuff of a latex Goldman dental mask, however Brain needed a material that would give him design flexibility before the next set of silicone moulds were cast. In 1986, Brain continued to make prototypes from latex with a range of modifications; the inclusion of an inflation line, a thin-walled elliptical ring in the cuff which resulted in equal expansion of the cuff, the creation of a larger size to increase the reliability of cuff seal pressure and a moulded back plate for the cuff. By December 1986, Brain was ready to conduct the first wholly independent trial and chose Dr John Nunn to be the recipient of the silicone prototypes to conduct the trial. "There were three outstanding advantages of the LMA in patients who breathed spontaneously. Firstly, excellent airway patency was obtained in 98% of patients and did not deteriorate during the course of the anaesthetic. Secondly, as no manual support of the jaw was necessary the hands of the anaesthetist were freed for monitoring, record keeping and other tasks. Thirdly, it was possible to maintain a clear airway throughout transfer of the patient to the recovery room." The publication of this trial in 1989 was critical in kickstarting the uptake of the laryngeal mask in the UK".
Read more about this topic: Laryngeal Mask Airway
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