Volume 21, Issue 2 (April 1976)
Concentrations of Ethanol in Two Segments of the Vascular System
The determination of ethanol is probably one of the most frequently requested tests in the forensic or clinical toxicology laboratory . Large differences in ethanol distribution between whole blood and various human tissue have been reported  as well as ethanol concentration gradients within human and animal vascular systems [3–8]. Forney  reported that during the absorption-distribution phase, after the oral administration of ethanol, the “concentration of alcohol in arterial blood may be 50 to 100 percent higher than it (is) in venous blood.” During this time blood from an arm vein will not truly reflect the concentration of ethanol supplied to the brain, where its effects are produced. These vascular ethanol concentration gradients generally have been ignored, possibly because the reports of other authors [3–6] have indicated that the arteriovenous (A/V) equilibrium of ethanol is attained rapidly in man when ethanol is administered by rapid intravenous infusion. Dundee et al  stated that after oral administration the A/V ratio reaches unity much more slowly than when alcohol is given intravenously. Harger  pointed to errors from using venous blood during the absorption phase after oral administration of ethanol. This work substantiates and extends the capillary-venous ethanol concentration differences reported in the literature and illustrates that equal capillary and venous ethanol concentration may not be achieved readily after the oral administration of ethanol to man.