Potential errors in the measurement of anesthetic partial pressure in blood.

ALTHOUGH it is easy to measure anesthetic partial pressures in gas mixtures, it is not straightforward in blood. A single-step technique has been described,' but more commonly the sample is equilibrated in a water bath with a similar amount of air, and the partial pressure of the anesthetic in the gas phase is measured. The equilibration reduces the partial pressure of anesthetic in the Factor. We report a simple way to prepare vials so that blood is oxygenated during equilibration, the vials are sampled at ambient pressure, and no correction factor is needed.