Subcutaneous and intramuscular hemodynamics and oxygenation after cold-spray application as monitored by near-infrared spectroscopy

Abstract

Context: Vapocoolant spray, commonly known as cold spray (CS), is a cryotherapy modality used in sports medicine, athletic training, and rehabilitation settings. Proposed physiologic effects of cryotherapy modalities include reductions in tissue blood flow, oxygenation, and cell metabolism in addition to attenuation of pain perception attributed to reduced superficial nerve conduction velocity. Objective: To examine the effects of CS on subcutaneous and intramuscular blood flow and oxygenation on the thigh muscle using near-infrared spectroscopy, an optical method to monitor changes in tissue oxygenated (O2Hb), deoxygenated (HHb), and total (tHb) hemoglobin. Design: Cross-sectional study. Setting: Muscle Biophysics Laboratory. Patients or Other Participants: Participants were 13 healthy adults (8 men, 5 women; age=37.4 6 6 years, body mass index = 27.4 6 2.6, adipose tissue thickness = 7.2 6 1.8 mm). Intervention(s): Conventional CS was applied to the vastus medialis muscles. Main Outcome Measure(s): Changes in chromophore concentrations of O2Hb, HHb, and tHb at superficial and deep layers were monitored for 5 minutes using a 2-channel nearinfrared spectroscopy. Results: Thirty seconds after CS application, we observed a decrease from baseline in O2Hb and tHb only in the superficial layer that was maintained for 3 minutes. Conclusions: Application of CS induced a transient change in blood flow and oxygenation of the superficial tissues with no change in deeper tissues over the healthy vastus medialis muscle. The limited physiologic effect of CS on the superficial hemodynamics and oxygenation of limb muscles may limit the therapeutic benefit of this cryotherapy modality to a temporary analgesic effect, a hypothesis that warrants a clinical trial on traumatized muscles.