Blood Alcohol Content

Blood Alcohol Content (BAC), also called blood alcohol concentration, blood ethanol concentration, or blood alcohol level is most commonly used as a metric of alcohol intoxication for legal or medical purposes. The definition of blood alcohol content is the concentration of alcohol in one's bloodstream, expressed as a percentage. It is used to determine whether a person is legally intoxicated, especially under a driving while intoxicated law. In the field of traffic safety, BAC is expressed as the percentage of alcohol in deciliters of blood–for example, 0.10 percent. A 160-pound man, for instance, will have a BAC of approximately 0.04 percent 1 hour after consuming two 12-ounce beers or two other standard drinks on an empty stomach. Laws have specific driver BAC limits, which vary from place to place.

A blood alcohol test measures the amount of alcohol (ethanol) in your body. Alcohol is quickly absorbed into the blood and can be measured within minutes of having an alcoholic drink. The amount of alcohol in the blood reaches its highest level about an hour after drinking. But food in the stomach may increase the amount of time it takes for the blood alcohol to reach its highest level. About 90% of alcohol is broken down in the liver camera.gif. The rest of it is passed out of the body in urine and your exhaled breath.

Alcohol has a noticeable effect on the body, even when consumed in small amounts. In large amounts, alcohol acts as a sedative and depresses the central nervous system. A blood alcohol test is often used to find out whether you are legally drunk or intoxicated. If this test is being done for legal reasons, a consent form may be required, but refusing to take the test may have legal consequences.

A test for blood alcohol level is done to:

• Check the amount of alcohol in the blood when a person is suspected of being legally drunk (intoxicated). Symptoms of alcohol intoxication include confusion, lack of coordination, unsteadiness that makes it hard to stand or walk, or erratic or unsafe driving.
• Find the cause of altered mental status, such as unclear thinking, confusion, or coma.
• Check to see whether alcohol is present in the blood at times when the consumption of alcohol is prohibited—for example, in under-age people suspected of drinking or in people enrolled in an alcohol treatment program.

Many medicines may change the results of this test. Be sure to tell your doctor about all the nonprescription and prescription medicines you take. The blood sample is taken from a vein in your arm. An elastic band is wrapped around your upper arm. It may feel tight. You may feel nothing at all from the needle, or you may feel a quick sting or pinch.