Transcutaneous CO2 tension measurement as an indicator of severity of hemorrhagic shock.

This study was undertaken to evaluate whether transcutaneous CO2 tension (PtcCO2) could be used as an indicator of the global systemic severity of hemorrhagic shock. PtcCO2 levels in ten anesthetized mongrel dogs were measured during hemorrhage and during volume restoration and were correlated with mixed venous CO2 tension ([Formula: see text]). After withdrawal of 30ml·kg-1 blood, both PtcCO2 and[Formula: see text] increased significantly (from 43±7 to 70±27 torr (P<0.05) and from 48±6 to 59±12 torr (P<0.05), respectively). Throughout the experiments, PtcCO2 levels changed almost in parallel to[Formula: see text] levels. However, changes in PtcCO2 exceeded those in[Formula: see text] from the end of hemorrhage, at which time cardiac output decreased to 35% of the baseline value, until the end of volume restoration, and the changes in PtcCO2 showed a close logarithmic relationship with[Formula: see text] (r=0.78,n=110). Additionally, arterio-transcutaneous CO2 tension gradients[Formula: see text] showed a close exponential correlation with cardiac output per body weight (CO/BW) during the shedding phase (r=0.85,n=60), although the correlation with CO/BW lessened during the retransfusion phase (r=0.55,n=60). PtcCO2 was roughly correlated with[Formula: see text] during hemorrhagic shock, and levels of PtcCO2 higher than[Formula: see text] reflected critical tissue perfusion.