Blood alcohol concentration and psychomotor effects

This study assessed the effect of intravenous alcohol infusions on psychomotor impairment and compared it with that of alcohol administered orally. Comparisons were made between three European drink-driving limits of blood alcohol concentration (BAC) (20, 50 and 80 mg 100 ml(-1)) and an oral dose of alcohol 0.75 mg kg(-1). Twelve volunteers, aged 22-34 yr, were recruited. At targets of 20, 50 and and 80 mg 100 ml(-1), the mean (SD) BAC was 22.1 (3.7), 51.5 (3.3) and 80.5 (4.2) mg 100 ml(-1), respectively. The peak BAC following an oral dose of alcohol 0.75 mg kg(-1) ranged from 19 to 68 mg 100 ml(-1). In psychomotor testing, choice reaction time deteriorated with increasing BAC and showed significant differences between baseline and the 50 (P<0.05) and 80 mg 100 ml(-1) (P<0.01) conditions. Dual-task secondary reaction time deteriorated with increasing BAC and showed a statistically significant difference between all groups and baseline (oral and 20 mg groups, P<0.05; 50 and 80 mg groups, P<0.01). Dual-task tracking in the 50 and 80 mg groups was significantly different from baseline (P<0.05 and P<0.01, respectively). Oral dosing resulted in widely variable BACs, making it difficult to assess psychomotor impairment reliably. An intravenous infusion enables the BAC to be maintained within a narrow range. This allows precision when investigating the effects of alcohol on psychomotor performance.