Effects of photobiomodulation therapy combined with static magnetic field (PBMT-sMF) in patients with severe COVID-19 requiring intubation: a pragmatic randomized placebo-controlled trial

Background: Photobiomodulation therapy (PBMT) when used isolated or combined with static magnetic field (PBMT−sMF) has been proven benefits on skeletal muscle increasing performance and reducing fatigue, increasing oxygen saturation, and modulating inflammatory process. However, it is unknown whether the effects observed with this therapy on respiratory muscles will be similar to the effects previously observed on skeletal muscles. Objective: We aimed to investigate whether PBMT−sMF is able to decrease the length of stay in the intensive care unit (ICU) and to reduce the mortality rate of patients with severe COVID−19 requiring invasive mechanical ventilation, increasing the respiratory function and modulating the inflammatory process. Methods: We conducted a prospectively registered, pragmatic, triple−blinded (patients, therapists and outcome assessors), randomized, placebo−controlled trial of PBMT−sMF in patients with severe COVID−19, requiring invasive mechanical ventilation, admitted to the ICU. Patients were randomly assigned to receive either PBMT−sMF (6 sites at the lower thorax − 189 J total, and 2 sites at the neck area − 63 J total) or placebo PBMT−sMF daily during all the ICU stay. The primary outcome was length of stay in the ICU defined by either discharge or death. The secondary outcomes were survival rate, muscle function of diaphragm, change in blood tests, change in mechanical ventilation parameters and change in arterial blood gas analysis. Results: A total of 30 patients underwent randomization (with 15 assigned to PBMT−sMF and 15 to placebo) and were analyzed. The length of stay in the ICU for the placebo group was 23.06 days while for the PBMT−sMF group was 16.26. However, there was no statistically difference between groups for the length of stay in the ICU (mean difference − MD = − 6.80; 95 ‰CI = − 18.71 to 5.11). Regarding the secondary outcomes were observed statistically differences in favor of PBMT−sMF for diaphragm thickness, fraction of inspired oxygen, partial pressure of oxygen/fraction of inspired oxygen ratio, C−reactive protein, lymphocytes count, and hemoglobin (p<0.05). Conclusion: Among patients with severe COVID−19 requiring invasive mechanical ventilation, PBMT−sMF was not statistically different than placebo to the length of stay in the ICU. However, it is important to highlight that our sample size was underpowered to detect statistical differences to the primary outcome. In contrast, PBMT−sMF increased muscle function of diaphragm, improved ventilatory parameters, decreased C−reactive protein levels and hemoglobin count, and increased lymphocytes count. Trial registration number (Clinical Trials.gov): NCT04386694.