Skin blood flow measurements during heat stress: technical and analytical considerations

During heat stress, the skin vasculature can greatly increase conductance secondary to vasodilation. The subsequent increase in skin blood flow allows for convective heat transfer from the core to the skin and between the skin surface and the surrounding environment. Measurement of skin blood flow, therefore, provides valuable information regarding heat exchange between the body and the environment. In addition, assessment of skin blood flow can be used to study vascular control mechanisms. Most often, skin blood flow is measured by venous occlusion plethysmography, Doppler ultrasound, laser-Doppler flowmetry, and, more recently, optical coherence tomography. However, important delimitations to each of these methods, which may be dependent on the research question, must be considered when responses from these approaches are interpreted. In this brief review, we discuss these methods of skin blood flow measurement and highlight potential sources of error and limitations. We also provide recommendations to guide the interpretation of skin blood flow data.