Effect of low-level laser therapy on blood flow and oxygen- hemoglobin saturation of the foot skin in healthy subjects: a pilot study

Abstract

Background and aims: This study on healthy test subjects intends to show whether one-off Low-Level Laser Therapy (LLLT) has an instant effect on the perfusion or the oxygenation of the skin tissue. These possible instant effects may have an influence on the accelerated wound healing which is often observed after application of LLLT, in addition to the usual postulated effects of LLLT which occur with a time delay normally.

Study design/materials and methods: The study was carried out double-blind and placebo-controlled in two batches of testing. The test subjects received one-off LLLT on a defined area of the arch of the foot. Simultaneously a placebo treatment was carried out on the corresponding contralateral area. In the first batch of tests, the blood flow was measured immediately before and after treatment using thermography and LDI. In the second batch of tests, the blood flow and the oxygen saturation were determined immediately before and after the treatment using an O2C device.

Results: No evidence that the LLLT has a significant instant effect on the circulation or the oxygen saturation could be found.

Conclusion: No immediate effect of an LLLT on the perfusion or oxygenation situation is to be expected with physiologically normal starting conditions. An additional investigation should be carried out in which either the radiation dose is varied or the starting conditions are pathological (e.g. chronic wounds) in order to rule out immediate effects on circulation or oxygen saturation as the cause of the improved wound healing which is often observed.

Keywords: Laser-doppler flowmetry; Low-power laser therapy; Oximetry; Oxygen to see; perfusion.

Figures

Fig 1

Area 1 (placebo area/RF) on the right foot and area 2 (LLLT area/LF) on the left foot are the radiation areas. Area 3 (placebo reference area/RR) and area 4 (LLLT reference area/LR) are the reference areas for the relevant radiation areas on the arch of the foot. In these areas, the O2C measurements were carried out (circulation) and the regions for the evaluation of the thermography and the LDI images were defined.

Fig 2

DMean temperatures of the various areas before and after radiation. Error bars represent SEM.

Fig 3

Temperature differences (radiation area minus the corresponding reference area) before and after radiation. Error bars represent SEM.

Fig 4

Mean blood flow as measured by Laser Doppler imaging before and after radiation. Error bars represent SEM.