Does the Alcohol Pretreatment Change Blood Ethanol Level in Blood Test?

ABSTRACT

PURPOSE: Ethanol is the most common toxic substance encountered clinically and is becoming increasingly important in forensic medicine. Generally, pre-treatment with an alcohol disinfectant such as isopropyl alcohol for blood sampling could influence evaluations and affect legal evidence. This study was performed to determine whether isopropyl alcohol affects the serum ethanol level. METHODS: Volunteers were prohibited from drinking alcohol and taking medication for 48 hours prior to participating. Pregnant volunteers and volunteers with abnormal liver enzymes or abnormal kidney function were excluded. Enrolled subjects had their blood collected from each arm to measure the alcohol concentration, one side was disinfected with povidone iodine and the other with isopropyl alcohol. After waiting one hour, they ingested 20g of alcohol and waited. After one hour, the serum ethanol levels were measured using the same method as the first sampling. RESULTS: Ten volunteers enrolled for this study. Without the alcohol intake, all serum ethanol levels were in the nondetectable range(<3 mg/dL) for both samples with either isopropyl alcohol or povidone iodine. After drinking alcohol, the serum ethanol level varied among individuals; the mean value of the serum ethanol levels in the alcohol preparation group was 21.08+/-4.85 mg/dL, which was significantly greater than that of the povidone iodine preparation group (19.71+/-5.47 mg/dL) (p=0.006). However, the Bland-Altman analysis showed that the precision of both groups was 1.230 mg/dL, which was less than the measurement error of the equipment (3.48 mg/dL). Therefore, there was no significant difference between the two groups with regard to the measurement error. CONCLUSION: Before alcohol intake, there was no influence on the blood alcohol concentration from the alcohol disinfection, and the result was reliable. After alcohol intake, the possible influence of pre-treatment alcohol on the serum ethanol level was less than the measurement error of the equipment used.