Abstract: 【Abstract】 Objective To evaluate the efficacy of medical cold patches in relieving burning pain and restoring skin homeostasis after hematoporphyrin monomethyl ether-based photodynamic therapy （HMME-PDT） for the treatment of port-wine stains. Methods Forty patients with port-wine stains in the middle face, who met the inclusion and exclusion criteria, were collected from Department of Dermatology, the Seventh Medical Center of Chinese PLA General Hospital from November 2019 to April 2021, and randomly and equally divided into test group and control group. Patients in the test group received cold compress with medical cold patches at treatment sites for 1 hour immediately after HMME-PDT, and then once a day for 3 consecutive days, while those in the control group received no special treatment and experienced a spontaneous recovery. Pain numeric rating scale （NRS） scores were recorded immediately, 0.5, 1 and 12 hours after HMME-PDT. Skin surface temperature was measured 10 minutes before, and immediately, 30 minutes and 1 hour after HMME-PDT. Transepidermal water loss （TEWL） and water content of the stratum corneum （WCSC） were measured 10 minutes before, and immediately, 24, 48 and 72 hours after HMME-PDT. The scabbing rate was calculated at weeks 1, 2 and 3 after HMME-PDT. Two-way repeated measures analysis of variance was used for comparisons of observation indicators at different time points before and after treatment, and Bonferroni or Sidak′s test was used for comparisons between groups and within groups. Results There were no significant differences in age, gender composition, TEWL or WCSC between the test group and control group before HMME-PDT （all P > 0.05）. Immediately after HMME-PDT, no significant difference in the NRS score was observed between the test group and control group （8.00 ± 1.17 vs. 8.20 ± 1.06, F = 0.30, P = 0.592）; at 0.5 and 1 hour after HMME-PDT, the NRS score was significantly lower in the test group （6.25 ± 1.29, 4.80 ± 0.77, respectively） than in the control group （7.15 ± 0.99, 6.50 ± 0.69, respectively, both P < 0.05）. Immediately after HMME-PDT, the skin surface temperature in the test group and control group increased to 35.21 ± 1.333 ℃ and 35.64 ± 0.832 ℃, respectively, and there was no significant difference between the two groups （P = 0.062）; at 30 and 60 minutes after HMME-PDT, the skin surface temperature in the test group was 29.11 ± 1.59 ℃ and 32.46 ± 1.07 ℃ respectively, which were significantly lower than those in the control group （35.01 ± 0.91 ℃, 34.86 ± 0.74 ℃, F = 212.63, 100.20, respectively, both P < 0.001）. At 48 and 72 hours after HMME-PDT, the TEWL in the test group was 12.44 ± 0.67 g·h-1·m-2 and 10.85 ± 0.81 g·h-1·m-2 respectively, which were significantly lower than those in the control group （14.61 ± 0.34 g·h-1·m-2, 14.93 ± 0.24 g·h-1·m-2, F = 195.87, 520.54, respectively, both P < 0.001）, while the WCSC was significantly higher in the test group （57.83 ± 9.29 AU, 52.64 ± 8.09 AU, respectively） than in the control group （43.87 ± 4.82 AU, 38.68 ± 5.33 AU, F = 24.41, 49.22, respectively, both P < 0.001）. At 1 week after HMME-PDT, scab formation was observed in 3 cases in the test group, as well as in 6 cases in the control group, and there was no significant difference in the scabbing rate between the two groups （P = 0.451）. Conclusion The application of medical cold patches after HMME-PDT for the treatment of port-wine stains can reduce skin surface temperature, exert analgesic effects, shorten duration of postoperative pain, and promote the recovery of skin permeability barrier function.

Key words: Port-wine stain, Photochemotherapy, Medical cold patch, Pain, Skin homeostasis