Sparks, low voltage sources and flammable anaesthetics

Battery operated laryngoscopes have two types of switching, one of which could cause an external spark. Laryngoscopes normally supply 2.8 volts and 0.67 amps, which theoretically gives ample energy for ignition of a cyclopropane/oxygen mixture. Attempts were unsuccessful to ignite a stoichiometric mixture of 17% cyclopropane in oxygen by breaking resistive circuits having up to 5.8 volts and 9.2 amps. It appears extremely unlikely that the common battery-powered laryngoscope can ignite a flammable mixture by sparking when being switched off.