• E Crosby and M Cleland.
• Department of Anesthesiology and Biomedical Engineering, University of Ottawa and the Ottawa Hospital-General Site, Ontario, Canada. ecrosby@fox.nstn.ca
• Can J Anaesth. 1999 Aug 1; 46 (8): 792-6.

PurposeTo determine luminance and light field characteristics and the effect of residual battery potential and luminance on light colour temperature in our used Macintosh #3 and #4 fibre-light (FLB) and bulb-light (BLB) laryngoscopes.MethodsWe used a power supply to provide laryngoscopes with potentials equivalent to those most commonly measured in the handles in use in our OR. Measurements were made under controlled, constant, conditions using a Pentax digital spotmeter (luminance) or a Minolta Color III colour temperature meter (light colour). Colour measurements were made while increasing the power source potential from 2-3 volts (v) in increments of 0.1 v. Light field measurements were made with a mm increment ruler mounted on the base of the test fixture.ResultsAt 2.5 and 2.8 v respectively, the #3 FLB produced luminance values of 23.9 +/- 11.4 and 41.7 +/- 17.2 cd x m(-2) (mean +/- SD), and the #4 FLB produced 58.6 +/- 21.4 and 90.9 +/- 32.2 cd x m(-2). Increasing potential increased luminance values (P < 0.001) and the #4FLB produced higher luminance values (P < 0.001). BLB produced higher luminance values than did FLB across all comparisons (P < 0.001). As potentials and luminance values decreased, light temperature was reduced (P < 0.001). There were no differences in light field dimensions noted in any comparison.ConclusionFifteen percent of the BLB did not meet the minimum luminance for laryngoscopy of 100 cd x m(-2), 92% of the FLB did not meet that same standard.

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