10.5 Notes10.5 Notes

Analysis of bloodAnalysis of blood

ObjectivesObjectives

► List and contrast laboratory procedures for List and contrast laboratory procedures for measuring the concentration of alcohol in measuring the concentration of alcohol in the blood.the blood.

► Relate the precautions to be taken to Relate the precautions to be taken to properly preserve blood in order to analyze properly preserve blood in order to analyze its alcohol content.its alcohol content.

► Understand the signification of implied-Understand the signification of implied-consent laws and the Schmerber v California consent laws and the Schmerber v California case to traffic enforcement.case to traffic enforcement.

Analysis of Blood for AlcoholAnalysis of Blood for Alcohol

►Gas chromatographyGas chromatography Most widely used approach for Most widely used approach for

determining alcohol levels in the determining alcohol levels in the blood blood

Separates alcohol from other volatile Separates alcohol from other volatile substance in the bloodsubstance in the blood

High degree of accuracyHigh degree of accuracy Used in most forensic labsUsed in most forensic labs

Another approachAnother approach

►SpectrophotometerSpectrophotometer measures conversion of alcohol to measures conversion of alcohol to

acetaldehyde in the oxidation process acetaldehyde in the oxidation process that is mediated by a coenzyme NAD to that is mediated by a coenzyme NAD to NADHNADH

Nicotin-amide-adenine-dinucleotideNicotin-amide-adenine-dinucleotide The NADH is measured and is related to The NADH is measured and is related to

alcohol consumption alcohol consumption Used in hospital settingsUsed in hospital settings

Blood Collection and Blood Collection and PreservationPreservation

►Drawn by qualified individual Drawn by qualified individual ►Procedure must be sterile with Procedure must be sterile with

nonalcoholic disinfectantsnonalcoholic disinfectants Negates any argument about false readingNegates any argument about false reading

►Sealed in airtight container with an Sealed in airtight container with an anticoagulant (EDTA or potassium anticoagulant (EDTA or potassium oxalate) and preservative (sodium oxalate) and preservative (sodium fluoride) fluoride)

►Stored in refrigerator Stored in refrigerator

►Anticoagulant prevents blood from Anticoagulant prevents blood from clottingclotting

►Preservative inhibits microorganisms Preservative inhibits microorganisms from destroying the alcoholfrom destroying the alcohol

►Signification factors to consider:Signification factors to consider: Storage temperatureStorage temperature Presence of preservativePresence of preservative Time of storageTime of storage

PostmortemPostmortem

►Ethyl alcohol can be generated as a Ethyl alcohol can be generated as a result of bacterial productionresult of bacterial production

►Samples collection from several body Samples collection from several body sitessites heart, femoral vein and cubital veinheart, femoral vein and cubital vein Also, vitreous humor fluids and urine Also, vitreous humor fluids and urine

should also be collected because they should also be collected because they don’t suffer from ethyl alcohol production don’t suffer from ethyl alcohol production

Alcohol and the LawAlcohol and the Law

►States have uniform blood alcohol States have uniform blood alcohol standards using the AMA and NSC standards using the AMA and NSC recommendation recommendation

►1992, Department of Transportation 1992, Department of Transportation recommended 0.08 as legal measurerecommended 0.08 as legal measure Became federal law in 2000Became federal law in 2000 States that don’t follow lose States that don’t follow lose

transportation fundingtransportation funding Commercial drivers = 0.04 legal limitCommercial drivers = 0.04 legal limit

Alcohol and the LawAlcohol and the Law

►Other countries have similar or Other countries have similar or standards less than .08standards less than .08

►1973 1973 –– Implied consent law Implied consent law –– submit to submit to the test or lose your license for 6 mo. the test or lose your license for 6 mo. to 1 yr. to 1 yr. Prevents a person’s refusal to take a test Prevents a person’s refusal to take a test

for intoxication on the constitutional for intoxication on the constitutional grounds of self-incriminationgrounds of self-incrimination

Standard is Standard is Schmerber v. CaliforniaSchmerber v. California

10.5 Questions10.5 Questions1. What analytical technique is the most widely used approach for

determining alcohol levels in blood?2. What type of disinfectant must be applied to a subject’s skin before

drawing blood? Why must such a disinfectant be applied?3. What type of container best ensures the preservation of blood

samples?4. What two substances should be added to a blood sample after

collection and why?5. How does each of the following factors affect alcohol’s stability in

blood: storage temperature, the presence of a preservative, and the time of storage?

6. When collecting postmortem blood samples for alcohol determination, why is it best to collect a number of blood samples from different body sites?

7. What blood-alcohol concentration is the current legal measure of drunk driving in the US as established by the National Highway Traffic Safety Administration?

8. What is an implied consent law? Why were such laws implemented?