British Journal of Anaesthesia, Vol 82, Issue 2 291-294, Copyright © 1999 by The Board of Management and Trustees of the British Journal of Anaesthesia
C. Keller, J. Brimacombe, A. Coorey, V. Wood and K. Keller
We have compared the liability of four laryngeal mask airway (LMA) devices
(standard, flexible, intubating and reusable) and a tracheal tube to
thermal damage from KTP and Nd:YAG lasers at two power densities used
commonly in airway surgery: 570 W cm-2 and 1140 W cm-2. Eighty-five airway
devices were tested: 24 standard LMA (silicone- based), 12 flexible LMA
(silicone-based, metal wires), 24 disposable LMA (PVC-based), one
intubating LMA (silicone and steel-based) and 24 PVC-based tracheal tubes.
Comparisons were made during laser strike to eight different targets: the
unmarked and marked part of the airway device tube; the unmarked part of
the airway device tube after application of blood; the cuff filled with air
or methylene blue dye; the unmarked flexible LMA tube on or between the
metal wires; and the epiglottic elevator bar of the intubating LMA. The
laser strike was continued for 30 s and each target was tested three times.
Three different, but identical, impact sites were used for each target.
There was no ignition of any airway device with either power density or
laser type. The silicone-based LMA were generally more resistant to flaring
and penetration than the PVC-based LMA and tracheal tube, but the
intubating LMA tube flared more rapidly with the KTP laser, and the
disposable LMA cuff was more resistant to penetration. Print markings,
blood and the metal wires of the flexible LMA reduced the thermal
resistance of the tube. Filling the cuff with methylene blue dye increased
the thermal resistance of all airway devices. We conclude that the
silicone-based LMA devices were more thermal resistant to KTP and Nd:YAG
laser strike than PVC-based devices with the exception of the disposable
LMA cuff and the intubating LMA tube.
EQUIPMENT
Liability of laryngeal mask airway devices to thermal damage from KTP and Nd:YAG lasers
Cairns Base Hospital, Cairns 4870, Australia; Department of Anaesthesia and Intensive Care Medicine, Leopold-Franzens University, 6020 Innsbruck, Austria; University of Queensland, Cairns Day Surgery, Cairns 4870, Australia; Department of Anaesthesia and Intensive Care, Cairns Base Hospital, Cairns; Cairns Day Surgery, Cairns 4870, Australia
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