The effect of ambient lighting on laser doppler imaging of a standardized cutaneous injury model

Dr Alan Pham1, Dr Erik La Hei1,2, Associate Professor John Harvey1,2, Professor Andrew Holland1,2,3

1The Children’s Hospital at Westmead Burns Research Institute, The Burns Unit and the NSW Severe Burns Injury Service, The Children’s Hospital at Westmead, 2Department of Paediatric Surgery, The Children’s Hospital at Westmead, 3Discipline of Paediatrics and Child Health, The Children’s Hospital at Westmead Clinical School, The University of Sydney

Objective: The aim of this study was to investigate the potential confounding effects of four different types of ambient lighting on the results of Laser Doppler Imaging (LDI) of a standardized cutaneous injury model.

Methods: After applying a mechanical stimulus to the forearm of a healthy volunteer and inducing a wheal and arteriolar flare (the triple response), we used a Laser Doppler Line Scanner to image the forearm under four different types of ambient lighting: light-emitting-diode (LED), compact fluorescent lighting (CFL), halogen, sunlight, and darkness as a control. A spectrometer was used to measure the intensity of light energy at 785nm, the wavelength used by the scanner for measurement under each type of ambient lighting.

Results: Neither the LED nor CFL bulbs emitted detectable light energy at a wavelength of 785nm. The graphical representation of perfusion unit values of the triple response measured by the scanner was similar between darkness, LED, and CFL light. Sunlight emitted 2mW at 785nm, with a slight variation tending more towards lower perfusion unit values compared to darkness. Halogen lighting emitted 6mW of light energy at 785nm rendering the graphical representation extremely difficult to interpret.

Conclusions: Based on our results, LED and CFL lighting does not appear to interfere with the results of LDI of cutaneous injuries. Both sunlight and especially halogen lighting have the potential to confound results. Any potential sources of sunlight should be reduced and halogen lighting completely covered or turned off prior to wound imaging.

Dr Alan Pham is currently the burns registrar at The Children’s Hospital at Westmead, which is the referral center for all paediatric burns in New South Wales, Australia. His interests include safe, efficient, and consistent burns care delivery in both an inpatient and outpatient setting as well as the long-term care of patients with significant hypertrophic scarring as a result of their burn injuries. Current research interests include RCT’s comparing Suprathel, Biobrane, and Acticoat in the mid-dermal burn as well as the use of PDL and CO2 lasers to treat problematic scars in pediatric burns patients.


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