Temperature-Controlled 830-nm Low-Level Laser Therapy of Experimental Pressure Ulcers

Abstract

This study was performed to evaluate the effectiveness of near-infrared low-level laser therapy (LLLT) treatment of pressure ulcers under temperature-controlled conditions. Little information is available regarding the potential thermal effects of near-infrared photo-radiation during LLLT. Pressure ulcers were created in C57BL mice by placing the dorsal skin between two round ceramic magnetic plates (12.0 x 5.0 mm, 2.4 g, 1 K Gauss) for three 12-h cycles. Animals were divided into three groups (n = 9) for daily light therapy (830 nm, CW, 5.0 J/cm(2)) on days 3-13 post ulceration in both groups A and B. A special heat-exchange device was applied in Group B to maintain a constant temperature at the skin surface (30 degrees C). Group C served as controls, with irradiation at 5.0 J/cm(2) using an incandescent light source. Temperature of the skin surface, and temperature alterations during treatment were monitored. The wound area was measured and the rate and time to complete healing were noted. The maximum temperature change during therapy was 2.0 +/- 0.64 degrees C in Group A, 0.2 +/- 0.2 degrees C in Group B and 3.54 degrees C +/- 0.72 in Group C. Complete wound closure occurred at 18 +/- 4 days in Groups A and B and 25 +/- 6 days in Group C (p </= 0.05). The percentage of the wound closure at 14 days was 75. 4 +/- 7.2% and 77.7 +/- 5.6% for Groups A and B, respectively (NS differences). However, animals in Group C demonstrated a wound closure of 36.3 +/- 4.8% (p < 0.05). These results demonstrate that the salutary effects of LLLT on wound healing are temperature independent in this model.