Abstract
Vasomotor reactivity, which is important to estimate neurogenic regulation of blood vessels in patients with different pathologies, is still assessed by occlusion plethysmography using sensors contacting the limbs. Recently we proposed a contactless approach for measuring blood flow changes during venous occlusion using imaging photoplethysmography [Kamshilin et al., Sci. Rep.7, 4642017]. In this work, the response of the vascular system on the occlusion was studied simultaneously by contact air-plethysmography system and remote optical system under illumination by incoherent polarized green light. A high correlation (r > 0.93) between the waveforms measured by both system was observed. Moreover, we found that the response of the optical system on the venous occlusion is uniform at the whole area of the forearm. The new optical technique is more convenient for assessment of the blood flow dynamics because it can be used for measurements in any part of the body. Method of imaging photoplethysmography is very promising for use in equipment intended for evaluation of neurogenic mechanisms of regulation of vascular blood flow.
Highlights
Assessment of the muscle blood flow and studying of the reactivity of blood vessels in response to various physiological impacts is an important approach for diagnosis of vasomotor regulation disorders in a wide range of patients
We study the properties of the imaging photoplethysmography (IPPG) signal using matrix singular value decomposition (SVD) [23] when applying venous occlusion tests
A significant excess of the first principal components (PCs) over all other PCs was found in all 14 experiments
Summary
Assessment of the muscle blood flow and studying of the reactivity of blood vessels in response to various physiological impacts is an important approach for diagnosis of vasomotor regulation disorders in a wide range of patients. More advanced metal-free electromechanical sensor with inelastic but flexible plastic line spanning around the limb [4,5] was proposed for measurements of forearm blood flow. All these methods require direct contact with a subject skin, which constrains their wide applications because of impossibility of measuring damaged limbs and necessity of proper selecting of the well-wrapping gauge. Nakano et al suggested assessment of venous compliance via measurements of skin-color changes nearby superficial veins caused by venous occlusion by digital color camera [9]. This technique has been validated only in the back of the hand
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