Effect of cold air cooling on the incidence of postinflammatory hyperpigmentation after q switched nd:yag laser treatment of acquired bilateral nevus of ota like macules

Abstract

Objective To investigate the effect of cold air cooling on the incidence of postinflammatory hyperpigmentation (PIH) after laser treatment in Asian patients. Design Randomized, controlled, split-face study. Setting Skin laser center of a university hospital. Patients Twenty-three Thai women with acquired bilateral nevus of Ota\u96like macules. Interventions Patients were treated using a 1064-nm Q-switched Nd:YAG laser at an average fluence of 7.0 J/cm2 using a 3-mm spot size. The same laser fluence was used on both sides of the face in individual patients. One randomly selected face side of each patient was cooled using a cold air cooling device during and 30 seconds before and after laser irradiation, and the other side was irradiated without cooling. Main Outcome Measures Occurrence of PIH was objectively evaluated by measuring the melanin index using a spectrometer, and it was subjectively assessed by 2 nontreating physicians before treatment and once weekly for 4 weeks. Results Of the 21 patients who completed the study, 13 (62%) and 5 (24%) developed PIH on the cooled and uncooled sides, respectively. One patient (5%) had PIH on both the cooled and uncooled sides, and 2 (10%) did not experience PIH. The cooled sides were significantly more likely to become hyperpigmented after laser irradiation than the uncooled sides (relative risk, 2.6; 95% confidence interval, 1.13-6.00; P =3D .03). The clinical evaluation corresponded to the spectrometer reading. Conclusion Epidermal cooling with cold air is associated with an increased risk of PIH after Q-switched Nd:YAG laser treatmen