title: Effect of an oxygen pressure injection (OPI) device on the oxygen saturation of patients during dermatological methyl aminolevulinate photodynamic therapy.
abstract: Methyl aminolevulinate photodynamic therapy (MAL-PDT) (a topical treatment used for a number of precancerous skin conditions) utilizes the combined interaction of a photosensitizer (protoporphyrin IX (PpIX)), light of the appropriate wavelength, and molecular oxygen to produce singlet oxygen and other reactive oxygen species which induce cell death. During treatment, localized oxygen depletion occurs and is thought to contribute to decreased efficacy. The aim of this study was to investigate whether an oxygen pressure injection (OPI) device had an effect on localized oxygen saturation levels and/or PpIX fluorescence of skin lesions during MAL-PDT. This study employed an OPI device to apply oxygen under pressure to the skin lesions of patients undergoing standard MAL-PDT. Optical reflectance spectrometry and fluorescence imaging were used to noninvasively monitor the localized oxygen saturation and PpIX fluorescence of the treatment area, respectively. No significant changes in oxygen saturation were observed when these data were combined for the group with OPI and compared to the group that received standard MAL-PDT without OPI. Additionally, no significant difference in PpIX photobleaching or clinical outcome at 3 months between the groups of patients was observed, although the group that received standard MAL-PDT demonstrated a significant increase (p<0.05) in PpIX fluorescence initially and both groups produced a significant decrease (p<0.05) after light irradiation. In conclusion, with this sample size, this OPI device was not found to be an effective method with which to improve tissue oxygenation during MAL-PDT. Further investigation is therefore required to find a more effective method of MAL-PDT enhancement.
authors.affiliation: Clinical Photobiology, European Centre for Environment and Human Health, Peninsula College of Medicine and Dentistry, University of Exeter, Knowledge Spa, Royal Cornwall Hospital, Truro, Cornwall, TR1 3HD, UK. eeblakey@hotmail.com
authors.forename: E
authors.initials: E
authors.lastname: Blake
authors.forename: J
authors.initials: J
authors.lastname: Allen
authors.forename: C
authors.initials: C
authors.lastname: Thorn
authors.forename: A
authors.initials: A
authors.lastname: Shore
authors.forename: A
authors.initials: A
authors.lastname: Curnow
mesh_terms: D000622:Aminolevulinic Acid / Q000031:analogs & derivatives* / Q000627:therapeutic use; D001913:Bowen's Disease / Q000097:blood / Q000188:drug therapy; D002280:Basal Cell Carcinoma / Q000097:blood / Q000188:drug therapy; D006801:Humans; D055623:Keratosis, Actinic / Q000097:blood / Q000188:drug therapy; D010100:Oxygen / Q000008:administration & dosage* / Q000097:blood; D010778:Photochemotherapy / Q000379:methods*; D017319:Photosensitizing Agents / Q000627:therapeutic use*; D011230:Precancerous Conditions / Q000097:blood / Q000188:drug therapy*; D011312:Pressure; D011524:Protoporphyrins / Q000627:therapeutic use; D012878:Skin Neoplasms / Q000097:blood / Q000188:drug therapy*
chemical_list: D017319:Photosensitizing Agents; D011524:Protoporphyrins; C475457:methyl 5-aminolevulinate; D000622:Aminolevulinic Acid; C028025:protoporphyrin IX; D010100:Oxygen