Description
Alcohol, Ethyl - Ethanol is the most often abused substance whose primary effect on the CNS varies with blood concentration.This test to measure the quantity of ethanol in the blood for the assessment of recent ethanol ingestion. Not all individuals experience the same effects at a given blood level. Other CNS depressants have an additive effect when taken in combination with ethanol. At high concentrations, ethanol elimination is relatively constant (zero order). Fatal concentration typically exceeds 0.4 g/dL. Blood concentrations of 0.3 g/dL are associated with coma. Ethyl alcohol is present in many medicinal liquids and mouthwashes.
Normal findings: 0-50 mg/dL or 0%-0.05%
Critical Values: 300 mg/dL or 65 mmol/L (SI units) (Note: chronic alcoholics can commonly have levels 300 mg/dL and begin to show signs of alcohol withdrawal even at elevated levels).
Suspected alcohol intoxication - the blood ethanol level is typically elevated to 100 to 300 mg/dL (32.6 to 65.2 millimol/L) in acute intoxication. Most fatalities occur with levels 400 mg/dL (86.8 millimol/L). The lethal dose is variable, depending in part on chronic versus sporadic ethanol use. Minimal lethal exposure in a nontolerant adult is 5 to 6 g/kg of body weight taken orally. In the pediatric population, minimum lethal exposure is 3 g/kg of body weight taken orally.Submersion - blood ethanol levels 100 mg/100 dL have been reported in about one-third of adolescent and adult submersion victims. Others have reported that 30% to 70% of submersion victims aged 15 years or older have alcohol in their blood.
Ethanol depresses the CNS and may cause reduced alertness, coma, and death.
Physiologic effects at specific ethanol concentrations:
Slowing of reflexes, impaired visual activity: 50 to 100 mg/dL (10.9 to 21.7 mmol/L)
CNS depression: 100 mg/dL ( 21.7 mmol/L)
Potentially fatal: 400 mg/dL ( 86.8 mmol/L)
The rate, but not extent, of alcohol absorption is affected by several factors, including the presence of food (particularly high-fat foods), amount of alcohol ingested, time frame for consumption, and metabolic differences among individuals. On an empty stomach, peak blood ethanol level may occur in 30 to 75 minutes; on a full stomach or when large amounts of food have been consumed, peak level may not occur until 3 hours after ethanol ingestion. Alcohol is metabolized in the liver. A 70-kg person with normal liver function can metabolize about 15 mg of alcohol per hour.
The universally accepted blood alcohol concentration results for legal purposes are reported in percent weight/volume units or g/dL truncated to 2 decimal places.
The level of ethanol in blood equating to intoxication differs by state and country statute.
Proper collection, handling, and storage of blood alcohol are important for medicolegal cases involving sobriety testing. The blood test is the specimen of choice for legal purposes.
When you drink alcohol, more than 90% of it is processed by your liver. The rest leaves your body in your urine, sweat, and breath. Ethanol moves quickly from your digestive tract–mostly your stomach–and is absorbed into your bloodstream. Your blood alcohol level continues to rise for 30 to 90 minutes after you have taken your last alcoholic beverage.
