Diminished reactive hyperemia in the skin of critically ill patients

Reactive hyperemia (RH) in the forearm skin after an arterial occlusion of 5 min was investigated in 29 ICU patients and 17 age-matched healthy control subjects using a transcutaneous Po2/Pco2 electrode heated to 37°C. There was no difference in preocclusive baseline Ptco2 between patients (8 ± 5 torr) and control subjects (8 ± 4 torr). Patients exhibited a significantly decreased RH (16 ± 9 torr) in comparison with control subjects (26 ± 8 torr) and a diminished CO2 elimination. There was no correlation between the RH response and the oxygen extraction ratio, Hgb concentration, and hemodynamic and blood gas variables in patients. In contrast with control subjects, there was a significant correlation between CO2 elimination from the skin and the amount of RH in patients. The finding of a diminished RH in the patients was not related to a specific disease but correlated with the degree of physiologic derangement as assessed by the APACHE II score.