Alcohol in the Circulatory System

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Alcohol in theCirculatory System

• Forensic Science
• Toxicology Unit

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• Two ways to measure alcohol in the blood
• 1. Direct chemical analysis of blood
• 2. Measure alcohol content of the breath

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Pathway of Blood

• 20 of alcohol ingested is absorbed thru stomach
  walls into the portal vein
• Remaining alcohol passes into the small intestine
• Once in the blood the alcohol goes to the liver
  and moves up to the heart
• Eventually, blood makes its way to the lungs

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Alveoli

• 250 million in lungs, located at the terminal
  ends of bronchial tubes
• It is the surface of these alveolar sacs that
  blood flowing through the capillaries comes into
  contact with fresh oxygenated air in the sacs

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• CO2, alcohol, or any other volatile substance
  will move from the capillaries into the air sacs
  to be exhaled
• Oxygen moves into the air sacs

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Henrys Law

• When a volatile liquid (alcohol) is dissolved in
  a liquid (blood) and is brought to equilibrium
  with air (alveolar breath) there is a fixed ratio
  between the concentration of the volatile
  compound (alcohol) in the air (alveolar breath)
  and its concentration in the liquid (blood) and
  this reaction is constant for a given temperature
  (34C)

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• What ?????

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• The ratio of alcohol in the blood to alcohol in
  alveolar air is approx. 2100 to 1..in other
  words 1 mL of blood will contain nearly the same
  amount of alcohol as 21 mL of alveolar breath.
• Thus..

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• Henrys Law becomes a basis for relating breath
  to blood alcohol concentration!

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Meanwhile..
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• The blood from the lungs will go back to the left
  side of the heart and then back out to the
  systemic (body) circulation.
• Arterial blood alcohol level is around 41 higher
  than the venous level 30 minutes after the last
  drink.

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• Blood
• Brain
• Barrier

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• A breath test results obtained during the
  absorption phase may be higher than results
  obtained from a simultaneous direct analysis of
  venous blood.

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• However,
• Once absorption is complete the difference
  between a blood test and a breath test should be
  minimal

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Breath Test Instruments

• The breathalyzer first developed in 1954

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• I t is a spectrophotometer that has been designed
  to measure the absorption of light passing thru
  the K2Cr2O7 solution at a single wavelength

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• Collects and measures alcohol content of alveolar
  breath
• The amount of breath collected is 52.5 mL
• Switch to analyze and the air is pushed through
  a glass ampule containing potassium dichromate
  and silver nitrate in sulfuric acid and water

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• Any alcohol present in the breath dissolves in
  the dichromate and is oxidized into acetic acid
• The dichromate is destroyed.

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• It is the extent of this destruction that is
  measured by the Breathalyzer and is related to
  the quantity of alcohol passed in the ampule

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IR absorption and/or with fuel cell

• Alcohol present is captured in breath chamber
• a beam of infrared light is aimed through the
  chamber
• A filter is used to select a wavelength of IR
  light at which alcohol will absorb

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Fuel Cell breath tester
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• Information is processed by a microprocessor and
  the percent blood-alcohol concentration is
  displayed on a digital readout
• It is also printed on a card to produce a
  permanent record of the test results

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Field Sobriety Testing

• Performed to ascertain the degree of the
  suspects physical impairment and whether or not
  an evidential test is justified.

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Psychophysical tests

• Horizontal gaze nystagmus
• Refers to an involuntary jerking of the eyes as
  they move to the side
• When bac is 0.10 the jerking will begin before
  the eyeball has moved 45 degrees to the side

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• Higher bac will cause jerking at smaller angles
• Barbituates/depressants can cause nystagmus

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Walk TurnOne-Leg Stand

• Tasks test the subjects ability to comprehend
  and accomplish two or more simple instructions at
  one time

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Drug Recognition Expert (DRE)

• Incorporates standardized methods for examining
  suspects to determine whether they have taken one
  or more drugs
• Ensures that each subject has been tested in a
  routine fashion
• Requires 30-40 minutes
• 3-5 month training program for police officers
• Must complete a Drug Influence Evaluation form

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Drug Influence Evaluation

• 1. Breath Alcohol Test
• 2. Interview of the Arresting Officer
• 3. Preliminary Examination
• 4. Examination of the Eyes
• 5. Divided Attention Tasks
• 6. Vital Signs Examination
• 7. Dark Room Examination
• 8. Examination of Muscle Tone
• 9. Examination for Injection Sites
• 10. Interview Other Observations
• 11. Opinion of the Evaluator
• 12. Toxicological Examination

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The Role of theToxicologist

• Complications
• Knowing what poison/drug without any precursory
  symptoms
• Not dealing with original concentrations (nano
  and micrograms)
• Has the body metabolized a lot of the drug? And
  how does it act in the system? For example,
  heroin is transferred into morphine almost
  immediately
• The drugs toxicity could be very different for
  different people

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• When possible, (with an alive victim) collect a
  urine/blood sample.

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Techniques Used in Toxicology

• Isolate remove drugs and other toxic agents
  from biological materials submitted as evidencee
• Most drugs fall into either the acid or base
  category, so

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• Controlling the pH of the water solutions can
  control the type of blood that can be removed
  from blood, alcohol, or tissues
• Ex acid drugs can be extracted from an acidic
  water solution with chloroform
• Acid drugs aspirin, barbituates
• Bases methadone, amphetamines, cocaine

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Identify a 2-step approach

• 1. screening
• Allows for examination of a large amount of
  specimens within a short period of time for a
  wide range of drugs
• TLC, GC and immunoassay (specific drug-antibody
  interactions) are used
• Must be confirmed

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• 2. Confirmation
• GC/MS is generally accepted as the confirmation
  test of choice
• The GC separates the sample into parts
• The MS bombards the sample with electrons which
  breaks it up into fragments which are analyzed (a
  unique fingerprint)

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Poisons
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Heavy Metals

• Arsenic
• Bismuth
• Antimony
• Mercury
• Thallium