JNL: Oxygen saturation and perfusion changes during dermatological methyl-aminolevulinate photodynamic therapy.

 

 

Br J Dermatol. 2011 Aug 1. doi: 10.1111/j.1365-2133.2011.10554.x. [Epub ahead of print]

Oxygen saturation and perfusion changes during dermatological methyl-aminolevulinate photodynamic therapy.

Tyrrell J, Thorn C, Shore A, Campbell S, Curnow A.

Source

Clinical Photobiology, European Centre for Environment and Human Health, Peninsula Medical School, University of Exeter, Knowledge Spa, Royal Cornwall Hospital, Truro, Cornwall, TR1 3HD, UK. Diabetes and Vascular Medicine, Peninsula NIHR Clinical Research Facility and Peninsula Medical School, University of Exeter, Royal Devon and Exeter Hospital, Barrack Road, Exeter, EX2 5AX.

Abstract

Background:   Methyl-aminolevulinate photodynamic therapy (MAL-PDT) is a successful topical treatment for a number of (pre)cancerous dermatological conditions. In combination, light of the appropriate wavelength, the photosensitiser, protoporphyrin IX (PpIX) and tissue oxygen result in the production of singlet oxygen and reactive oxygen species inducing cell death. This study investigates real-time changes in localised tissue blood oxygen saturation and perfusion in conjunction with PpIX fluorescence monitoring for the first time during dermatological MAL-PDT. Methods:  Oxygen saturation, perfusion and PpIX fluorescence were monitored non-invasively utilising optical reflectance spectroscopy, laser Doppler perfusion imaging and a fluorescence imaging system respectively. Patients attending for standard dermatological MAL-PDT were recruited to this ethically approved study and monitored prior to, during and after light irradiation. Results:  Significant reductions in mean blood oxygen saturation (P<0.005) and PpIX fluorescence (P<0.001) were observed within the first minute of irradiation (4.75 Jcm(-2) ), whilst in contrast perfusion was observed to significantly increase (P<0.01) during treatment. The changes in oxygen saturation and PpIX fluorescence were positively correlated during the initial phase of treatment (r(2) =0.766). Conclusion:  Rapid reductions in the localised blood oxygen saturation have been observed to occur clinically for the first time within the initial minutes of light irradiation and positively correlate with the concurrent PpIX photobleaching. Furthermore perfusion increases suggesting that the microvasculature compensates for the PDT induced oxygen depletion.

Copyright © 2011 British Association of Dermatologists.

PMID:

21801159

[PubMed - as supplied by publisher]

 

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