Laser research: Microcirculation, abstract and studies
Photomedicine and Laser Surgery Volume 30, Number 4, 2012
Michael C.H. Mak, M.Sc.,1,2 and Gladys L.Y. Cheing, Ph.D.1
Objective: The purpose of this study was to evaluate the influence of monochromatic infrared energy (MIRE) on the microcirculation of the skin surface of the feet in healthy subjects. Background data: Near-infrared energy was shown to increase microcirculation in an animal study. In humans, only one case study demonstrated that MIRE increases microcirculation in the skin of the lower limbs.
Methods: Thirty healthy volunteers were recruited and randomly allocated into three groups to receive either: (1) active MIRE; (2) sham MIRE (placebo group); or (3) warm packs (control group) on the feet. The MIRE device comprised an array of 60 x 890nm LEDs attached to flexible pads (3 Ã�Â· 7.5 cm). Each diode spot size was 0.2 cm2, and each LED power was 12mW with a power density of 60 mW/cm2. The arrays were placed in direct contact with the skin for 30min delivering a total fluence of 108 J/cm2 over an area of 22.5 cm2. Capillary blood cell velocity (CBV) and superficial skin blood flow (flux) were recorded before and after intervention.
Results: Significant differences among the three groups were recorded in both CBV and flux (both p < 0.05). Post-hoc comparisons indicated that a significantly greater increase in both CBV and flux occurred in the active MIRE group than in the placebo group and control group (all p < 0.05).
Conclusion: A 30-min MIRE produced a significantly greater increase in the CBV and flux of the feet in the active MIRE group than in the placebo and control groups.
The present study was conducted to explore the effects of LLLI on microcirculation. We investigated the effects of LLLI on rat mesenteric microcirculation in vivo, and on cytosolic calcium concentration ([Ca2+]i) in rat vascular smooth muscle cells (VSMCs) in vitro. LLLI caused potent dilation in the laser-irradiated arteriole, which led to marked increases in the arteriolar blood flow. The changes were partly attenuated in the initial phase by the superfusion of 15 microM L-NAME, but they were not affected by local denervation. Furthermore, LLLI caused a power-dependent decrease in [Ca2+]i in VSMCs. The circulatory changes observed seemed to be mediated largely by LLLI-induced reduction of [Ca2+]i in VSMCs, in addition to the involvement of NO in the initial phase.
Six healthy volounteers were irradiated on their right pianta pedis with 5J/cm2 and a fluence rate of 100 mW/cm2. T1-weighted MRI was used to quantify the time-dependent local accumulation of Gadolinium DPTA, which semi-quantitatively reflects local blood flow. Images were obtained before and after laser application. LLLT resulted in an increase of signal to noise ratio of more than 0.34 (range 0.23-0.63) after irradiation according to contrast enhanced MRI. Increased blood flow offers an explanation for the clinical observation of improved wound healing and reduced pain after LLLT. The effect might complete and improve the outcome of other therapeutic modalities such as tumor ionizing radiation therapy and local chemotherapy.
Laserneedles represent a new non-invasive optical stimulation method which is described for the first time in this paper. We investigated 27 healthy volunteers (mean age+/-SD: 25.15+/-4.12 years; range: 21-38 years; 14 female, 13 male) in a randomised cross-over trial to study differences between laserneedle acupuncture and manual needle acupuncture in specific cerebral parameters. Mean blood flow velocity (v(m)) showed specific and significant increases in the ophthalmic artery during laserneedle stimulation (p=0.01) and during manual needle stimulation ( p<0.001) at vision-related acupoints. At the same time insignificant alterations in v(m) were found in the middle cerebral artery for both acupuncture methods. The eight laserneedles used in this study were arranged at the end of the optical fibres. Each fibre was connected to a semiconductor laser diode emitting at 685 nm with a primary output power of about 55 mW. Optical stimulation using properly adjusted laserneedles has the advantage that the stimulation can hardly be felt by the patient and the operator may also be unaware of whether the laserneedle system is active, and therefore true double blind studies in acupuncture research can be performed.
Was Studied Through Laser Speckle Flowgraphy (LSF) 40 rats were divided into four groups. Two groups had random pattern flaps, two had axillary pattern flaps with the dominant vessels intact. Flaps were raised and peripheral blood flow assessed through LSF. Laser irradiation was performed in two groups, either directly on the dominant vessel or at one point on the distal part of the flap. The blood flow directly after irradiation was higher than before irradiation. At day 5 there was a clear difference between the irradiated and the non-irradiated flaps. The flaps irradiated at the dominant vessels had a slightly better outcome than those irradiated at the Kobayashi M et al. Studies of the diode laser therapy on blood supply in the rat model. Proc. 2nd Congress World Assn for Laser Therapy, Kansas City, September 1998; p. 70-71.