Comparison of arterialized venous with arterial blood propofol concentrations during sub-anaesthetic infusions in volunteers

We have compared propofol concentrations in arterial and arterialized venous blood (from the radial artery at the wrist and a vein in the opposite forearm) in five volunteers during a sub-anaesthetic increasing infusion regimen designed to produce pseudo-steady-state arterial concentrations of 0.06, 0.17 and 0.43 micrograms ml-1. As in a previous study, we found no statistically significant difference between sampling sites (P = 0.66). However, changes in the method of arterialization yielded a reduction in the observed variability, with the arterialized venous propofol concentration lying within +/- 23% (95% reference interval) of the corresponding arterial concentration compared with 1 +/- 43%, as reported previously.