Noninvasive monitoring of human muscle oxygenation during exercise by near-infrared spectroscopy

Describes an instrument, based on near infrared spectroscopy and measuring the muscle reflectance of the deoxygenated (Hb) and oxygenated (HbO2) components of hemoglobin-myoglobin. The light generated by two laser diodes operating at 750 nm for Hb and at 810 nm for both Hb and HbO2 is transmitted to the tissue. The backscattered light is conveyed to a sensitive photon detector. The instrument is connected to a PC for data collection and storage. The system has been tested in 20 CAD patients performing a bicycle exercise test. A second exercise test was repeated in the same conditions. The measurement reproducibility was evaluated comparing the computed 750/810 parameter in the two trials with: (A) regression analysis for different exercise loads. (B) t test analysis carried out on 12 parameters extracted from the 750/810 waveform; no significant differences were found in any parameter. (C) Intraclass reliability correlation computed on the above defined parameters, which showed excellent scores.<>