Quantification of ischemic muscle deoxygenation by near infrared time-resolved spectroscopy

The purpose of this study was to quantify muscle deoxygenation in human ske letal muscles using near infrared time-resolved spectroscopy (NIRTRS) and c ompare NIRTRS indicators and blood saturation. The forearm muscles of five healthy males (aged 27-32 yrs,) were monitored for changes in hemoglobin sa turation (SO2) during 12 min of arterial occlusion and recovery. SO2 was de termined by measuring the temporal profile of photon diffusion at 780 and 8 30 nm using NIRTRS, and was defined as SO2-TRS. Venous blood samples were a lso obtained for measurements of SvO2, and PvO2. Interstitial PO2(PintO2) w as monitored by placing an O-2 electrode directly into the muscle tissue. U pon the initiation of occlusion, all parameters fell progressively until re aching a plateau in the latter half of occlusion, It was observed at the en d of occlusion that SO2-TRS (24.1 +/- 5.6%) agreed with SvO2(26.2+/-6.4) an d that PintO2 (14.7+/-1.0 Torr) agreed with PvO2 (17.3+/-2.2 Torr). The res ting O-2 store (oxygenated hemoglobin) and O-2 consumption rate were 290 mu M and 0.82 mu M s(-1), respectively, values which reasonably agree with th e reported results. These results indicate that there was no O-2 gradient b etween vessels and interstisium at the end of occlusion. (C) 2000 society o f Photo-Opical Instrumentation Engineers. [S1083-3668(00)01301-0].