Reproducibility of parameters of postocclusive reactive hyperemia measuredby near infrared spectroscopy and transcutaneous oximetry

The purpose of this study was to investigate post occlusive hyperemic respo nse using near infrared spectroscopy (NIRS) and transcutaneous oximetry (Tc pO(2)). Five minute arterial occlusion on the calf muscle was performed in six healthy volunteers (mean age 29, range 23-34 years, mean TcpO(2) at res t 53 mm Hg, range 47-58 mmHg, and ankle brachial index between 1 and 1.2). Oxygen partial pressure at rest. oxygen consumption (VO2) during ischemia, recovery times and resaturation rates after arterial occlusion were determi ned and new parameters for evaluation of the level of vascular disorders of lower limbs are suggested. The reproducibility of the signals was studied by repeating the same protocol on each subject four to six times. Repeated measurements showed no significant difference among trials, indicating that the measurements were reproducible. The mean values of the coefficient of variability for suggested parameters varied between 6% and 30% (mean value 17%). Interindividual variations of parameters are higher and can be explai ned by differences in fat/muscle ratio and in the measured tissue volume of the NIPS signal. Simultaneous measurements of NIRS and TcpO(2) showed diff erent responses to ischemic conditions, due to the different physiological levels of oxygen assessment. The combined use of both methods yields deeper insight into conditions of blood flow and tissue oxygenation. (C) 2000 Bio medical Engineering Society. [S0090-6964(00)00302-7].