Background:Many treatments have been tried in therapy systemic sclerosis (SSc) patients but use of hyperbaric oxygen therapy (HBOT) is very limited.Objectives:To assess the effects of HBOT to quality of life and state of microcirculation in SSc patients.Methods:18 female patients aged 29-68 years (mean 57 years) with limited SSc and digital or leg ulcers were included in this work. The HBOT protocol comprised 20 sessions 5 day/weekly, 60 min, 100% oxygen at 2.2 ATA. The treated patients were evaluated at baseline and after 20 HBOT sessions. Evaluation consisted of physical examination, capillaroscopy, pulmonary function tests, biochemical analyses, socio-demographic and clinimetric questionnaires: Systemic Sclerosis Questionnaire (SySQ) and Health Assessment Disaability index Questionnaire (HAQ-DI).Results:Mean value [before: after, mean (range)] for SySQ [15.5 (4-48) vs 9.0 (3-31)], HAQ-DI [0.60 (0-2.88) vs 0.35 (0 -1.75)], erythrocyte sedimentation rate [21 (4-42) vs 12 (3-27)], forced vital capacity (96.61±14.44% vs 115.94±16.69%), diffusing lung capacity of carbon monoxide (73.61±6.63% vs 87.33±9.30%) significantly improved after HBOT sessions (p<0.001). There was no significant changes in the total number of capillaries (325 vs 338, p=0.235), mean number of enlarged capillaries (21 vs 27, p=0.182), giant capillaries (14 vs 14, p=0.235) and ramified/bushy capillaries (14 vs 13, p=0.178) before and after HOBT. All patients had digital ulcers, and 5 patients had bilateral lesions (digital and leg ulcers). Mean size of ulceration before HBOT was 12x11mm, and after therapy was 4x4mm (p<0.001). Three patients had digital gangrene. Amputation was not require for any.Conclusion:Our data confirm the efficacy of HBOT in treating SSc patients. Further studies are required to evaluate the protocol and to understand the durattion of the clinical effect.References:[1]Mirasoglu B, Bagli BS, Aktas S. Hyperbaric oxygen therapy for chronic ulcers in systemic sclerosis - case series. Int J Dermatol. 2017;56(6):636-640.[2]Gerodimos C, Stefanidou S, Kotsiou M, et al. Hyperbaric oxygen treatment of intractable ulcers in a systemic sclerosis patient.Aristotle Un Med J. 2013;(40)3:19-22.[3]Wallace DJ, Silverman S, Goldstein J, Hughes D. Use of hyperbaric oxygen in rheumatic diseases: case report and critical analysis. Lupus. 1995;4(3):172-5.Disclosure of Interests:Slavica Pavlov-Dolijanovic: None declared, Vesna Koletic: None declared, Nada Vujasinovic Stupar: None declared, Nemanja Damjanov Grant/research support from: from AbbVie, Pfizer, and Roche, Consultant of: AbbVie, Gedeon Richter, Merck, Novartis, Pfizer, and Roche, Speakers bureau: AbbVie, Gedeon Richter, Merck, Novartis, Pfizer, and Roche