Introduction There is a paucity of information about the light and heat output of laryngoscopy equipment. We became concerned about the potential of a laryngoscope blade burn following an episode during intubation We mounted an in-vitro study of larynoscopes to determine the temperatures reached during clinical use.

Methods The temperature of the incandescent light bulb from ten different laryngoscopes was measured using a Real Time controller from National Instruments for data logging into a PC.

A second set of tests were performed using two fibre optic laryngoscope head designs. The temperature was measured every half a second for ten minute duration from the point in time at which the light was turned on in all devices. The temperature fall times from closing and simultaneous turning off of the laryngoscope light were also recorded.

Results Peak temperature was found to be consistently above 50 °C in four different brands of light bulb protruding laryngoscope heads. On closing the laryngoscope temperatures were all below 30° at a one minute interval. In comparison, the fibre optic laryngoscope heads did not reach temperatures higher than 27.5°C.

Discussion The findings from our study indicate that within 30 seconds all ten laryngoscopes, with light-bulb sources, had gained significant heat to cause thermal injury to neonatal skin. LED laryngoscopes did not.

Conclusions We recommend that the laryngoscope blade is not left open prior to intubation and that it is closed between intubation attempts.