Hemodynamic variations measured with near-infrared spectroscopy in

human forearm muscles in response to venous occlusion:

An electrical model

Vo Van Toi*, Matthew L. Hoimes, Shalini Nadgir, and Sergio Fantini

Department of Biomedical Engineering, Bioengineering Center,

Tufts University, 4 Colby Street, Medford, MA 02155

ABSTRACT

We present data collected with near-infrared spectroscopy on the human forearm (brachioradialis muscle) to characterize the hemodynamic response to venous occlusion in muscle. Venous occlusion was achieved in the upper arm by inflating a pneumatic cuff to a pressure of 60 mmHg. We performed absolute measurements of concentration and oxygen saturation of hemoglobin on six healthy adult human subjects. On all six subjects, we consistently found that during a 40-s venous occlusion the hemoglobin concentration increases (by 5.6±2.3 mM), while the oxygen saturation of hemoglobin decreases (by 2.1±0.7%). This accumulation and desaturation of blood in the forearm in response to the upper arm occlusion can be described with an electrical model in which the charge stored by a capacitor represents the local blood volume, and the electrical current represents blood flow.

Keywords: Near-infrared spectroscopy, hemoglobin concentration, oxygen saturation, venous occlusion, circulatory system, vascular compliance, electrical modeling.