Microcirculatory Response to Photobiomodulation-Why Some Respond and Others Do Not: A Randomized Controlled Study

Area of Science:

• Biomedical Engineering
• Photomedicine
• Microcirculation Research

Background:

• Photobiomodulation (PBM) therapy is used for wound healing and pain relief, with known effects on blood flow.
• Individual responses to PBM vary, necessitating investigation into influencing factors.
• Advanced noninvasive methods are crucial for monitoring microcirculatory activity during PBM.

Observation:

• A randomized controlled trial involved 20 healthy volunteers receiving red or near-infrared light PBM.
• Microcirculatory blood volume, blood flow, and skin temperature were monitored using photoplethysmography, laser Doppler flowmetry, and thermal imaging.
• Responders were defined as those with a skin temperature change of ≥0.5°C from baseline.

Findings:

• Near-infrared PBM significantly increased microcirculatory flow by 27%, rising to 54% during follow-up (p<0.05).
• Red light PBM did not significantly increase median flow.
• Responders (skin temperature 33-37.5°C) showed rapid increases in blood flow and volume within 2.5 minutes.

Implications:

• PBM induces arteriolar vasodilatation, leading to increased tissue perfusion.
• The therapeutic effect of PBM is wavelength-dependent and influenced by baseline skin temperature.
• Understanding these physiological parameters can guide patient-specific PBM treatment strategies.