RESUMO
Objective: We aimed to evaluate the effects of photobiomodulation therapy on the respiratory function and laboratory parameters in COVID-19 participants with respiratory involvement. Methods: A randomized, double-blind controlled design was used. This study was conducted at Koosar Hospital. Thirty participants with COVID-19 who were hospitalized met the inclusion criteria and were randomly assigned to two groups. Patients were treated with a program of five sessions of high-power photobiomodulation (intervention group) and placebo photobiomodulation (control group). Both groups received standard treatment. Outcomes were assessed before and after the intervention (two sessions), according to the immune system function and laboratory tests for the respiratory rate (RR), oxygen saturation, and inflammatory factors, including C-reactive protein (CRP), white blood cells, and interleukin-6 (IL-6), as well as complete blood count (CBC), hematocrit, hemoglobin, and ferritin. Results: Findings indicated that the values of ferritin, erythrocyte sedimentation ratio, CRP, IL-6, O2 saturation, and RR were significantly improved after the intervention in both groups (p < 0.05). Independent T-test analyses also indicated significant differences in the CRP, IL-6, and O2 saturation in the photobiomodulation group compared with the control group after the five-session intervention (p < 0.05). Conclusions: Application of photobiomodulation is recommended for treatment of respiratory problems in patients with COVID-19 to improve clinical signs and control inflammatory factors. Clinical Trial Registration: IRCT2017070934969N1.