Muscle Blood Flow and Oxygen Utilization Measured by Near-Infrared Spectroscopy during Handgrip Exercise in Chronic Respiratory Patients

[Purpose] The purpose of this study was to evaluate tissue oxygen utilization and blood flow in patients with chronic respiratory failure (CRF). [Subjects] The subjects were divided into three groups: twelve subjects with chronic respiratory failure, twelve healthy older subjects, and thirteen healthy young subjects. [Method] A near infrared spectrometer was used to monitor tissue oxygenation, and the probe was placed over the flexor muscle. The subjects performed 3min rhythmic handgrip (HG) exercise at 10 and 30% of maximum voluntary contraction force in a random order. Forearm blood flow was estimated by the rate of increase in the sum of oxy-hemoglobin (OxyHb) and deoxy-hemoglobin (DeoxyHb) during venous occlusion, and muscle oxygen utilization by the rate of decrease in the difference between OxyHb and DeoxyHb during arterial occlusion. [Results] Forearm blood flow in the CRF group was significantly lower compared to the older group during 10% HG and the younger group in 30% HG. Muscle oxygen utilization in the CRF group was significantly higher than the older and young groups in 10% HG. [Conclusion]We conclude that the CRF patients desaturate their muscles more than normal control subjects at a lower work level due to insufficiency of blood flow to the exercising muscles.