Muscle Near-Infrared Spectroscopy Signals versus Venous Blood Hemoglobin Oxygen Saturation in Skeletal Muscle.

Purpose: The study aimed to examine the relationship between near-infrared spectroscopy (NIRS) signals and venous hemoglobin oxygen saturation (O2Hb%) and venous oxygen concentration (CvO2).

Methods: Gastrocnemius muscles (GS) in six dogs were surgically isolated and pump perfused. NIRS signals were recorded, and venous blood samples were collected at constant flow rates (control flow, high flow, and low flow) at rest as well as during electrically stimulated tetanic muscle contractions at rates of one contraction per 2 s (1/2 s) and two contractions per 3 s (2/3 s).