Los Angeles DUI Blood Tests: Artery Versus Vein

When a driver is arrested on suspicion of driving under the influence in Los Angeles, he or she will be given the option of taking either a breath or blood test. Neither test is perfect and there may be ways of challenging the results of both the breath and blood test. There may be ways to challenge the results of the blood test, especially if there were issues with how the sample was stored or whether the sample tested was whole blood or plasma. Another issue that may ultimately affect the results of the blood analysis is whether the blood sample was drawn from an artery or a vein.

In most DUI cases, the blood draw comes from a vein instead of an artery. Studies have shown that BAC results from venous blood can be substantially different from the results from arterial blood when compared. Arterial blood sends alcohol to the brain and thus it is this blood that may actually provide a stronger indication regarding whether or not a person is impaired.

Researchers have found that the blood alcohol content of arterial blood is higher than the BAC in venous blood during the initial absorption phase that occurs after a person first consumes alcohol and it is being absorbed and distributed throughout the body. The opposite is also true and a person’s BAC from venous blood is higher than a sample taken from an artery during the elimination phase that occurs as the body breaks down and eliminates alcohol.

When a person consumes alcohol, there are three phases that will affect the person’s measured blood alcohol content. The first phase is the absorption phase in which alcohol is distributed throughout the body and during which the person will have a rising blood alcohol level. There is the peak or plateau phase that occurs after drinking has ceased where a person’s BAC will level off as the alcohol is distributed evenly throughout the body. And finally there is the elimination phase, as the alcohol consumed passes through the liver and is eliminated. A person’s BAC will drop during the final phase.

A blood sample taken from a vein may be unreliable because it will provide lower than usual results during the absorption phase and higher than usual results in the elimination phase. In fact, during the elimination phase a blood sample taken from a vein can have a BAC result that is .05 percent higher than a sample taken from an artery. This can be a huge difference in determining whether or not the driver’s BAC exceeded the 0.08 percent legal threshold.

Even if a driver has waited a substantial amount of time after drinking, a venous blood sample may provide results that do not correlate with the driver’s actual level of impairment. The driver’s attorney may be able to challenge the BAC results from the venous blood sample and show that the results were elevated and do not reflect the driver’s true BAC or level of impairment.

In many cases, the technician or nurse who was responsible for performing the blood draw may not be able to recall whether or not the blood sample was taken from the defendant’s artery or vein. If this is the case, there may be serious questions about the accuracy and reliability of the blood sample used as evidence against the defendant.

If the prosecution is introducing the defendant’s blood sample as evidence of his or her blood alcohol content, it may be necessary for the defense to call an expert witness to explain the difference between arterial and venous blood and show how the defendant’s BAC results were elevated and the true BAC at the time of driving may have been lower when considering absorption and elimination rates.

If you have been arrested for DUI and have provided a blood sample for testing, it is crucial that you speak with a Los Angeles DUI Attorney right away. As a former Deputy District Attorney with over 14 years of prosecutorial experience, Lawyer Michael Kraut works with the top experts and understands how best to challenge prosecution evidence in DUI cases.

For more information about venous versus arterial blood analysis in Los Angeles DUI cases, and to schedule your free consultation, contact Michael Kraut at the Kraut Criminal & DUI Lawyers located at 6255 Sunset Boulevard, Suite 1520, Los Angeles, CA 90028. Mr. Kraut can be reached 24/7 at 888-334-6344 or 323-464-6453.