Microcirculation of striated muscle in closed soft tissue injury: effect on tissue perfusion, inflammatory cellular response and mechanisms of cryotherapy. A study in rat by means of laser Doppler flow-measurements and intravital microscopy

The authors investigated the effects of closed soft tissue injury (CSTI) and cryotherapy on microvascular perfusion by means of laser Doppler flowmetry. In a different protocol interactions between leukocytes and the microvascular endothelium of skeletal muscle, which are first steps in local inflammatory response were documented in an intravital microscopy model. Rats were chronically instrumented with dorsal skinfold chambers. Leukocyte rolling and adherence in postcapillary venules of striated muscle before and after standardized muscle contusion (group T: n = 6), cryotherapy following muscle contusion (TK: n = 6) or sham contusion (group N: n = 6) were quantitated prospectively and in random order using intravital microscopy. Tissue perfusion was assessed by laser Doppler flowmetry in the microvasculature of the flap over a period of 96 hours following CSTI (group T: n = 8), cryotherapy following CSTI (group TK: n = 8), sham trauma (group N: n = 8, control 1), or cryotherapy following sham trauma (group K: n = 8, control 2). 300 minutes after trauma the number of rolling and adherent leukocytes in striated muscle microvasculature was significantly reduced by cryotherapy. We found an acute effect of cryotherapy on perfusion of traumatized tissue (reduction of perfusion around 25 %). However, there was no long-term effect (96 hours evaluation) on microvascular perfusion of cryotherapy either in the presence or absence of CSTI. The effectiveness of ice application in reducing edema in striated muscle following contusion may be due in part to a reduction of the leukocyte/endothelial interactions accompanying CSTI.