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134 Cards in this Set
- Front
- Back
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Which toxic agent is a colorless, odorless, tasteless gas that is a product of incomplete combustion of carbon-based material? |
carbon monoxide |
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This toxic agent can come from cigarette smoke, gasoline engines, and improperly ventilated home-heating units. |
carbon monoxide |
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The affinity of carbon monoxide for hemoglobin is 250 times that of oxygen and forms what? |
carboxyhemoglobin |
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Why does carbon monoxide cause hypoxia? |
It increases oxygen affinity of remaining subunits so less oxygen is released to the tissues. |
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If there's 10% carboxyhemoglobin, what is the body's response? |
shortness of breath on vigorous muscular exercise |
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If there's 20% carboxyhemoglobin, what is the body's response? |
shortness of breath on moderate exertion and a slight headache |
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If there's 30% carboxyhemoglobin, what is the body's response? |
headache, irritation, ready fatigue, and disturbance of judgment |
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If there's 40-50% carboxyhemoglobin, what is the body's response? |
Headache, confusion, collapse and fainting |
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If there's 60-70% carboxyhemoglobin, what is the body's response? |
unconsciousness, respiratory failure and death if exposure |
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If there's 80% carboxyhemoglobin, what is the body's response? |
rapid fatality |
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If there's greater than 80% carboxyhemoglobin, what is the body's response? |
immediate fatality |
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What is the treatment for carbon monoxide? |
exposure to oxygen |
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The half life of carboxyhemoglobin is what when the patient breathes room air? |
5 to 6 hours |
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The half life of carboxyhemoglobin is what when the patient breathes 100% oxygen? |
1.5 hours |
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The half life of carboxyhemoglobin is what when the patient is placed in hyperbaric oxygen at 2 to 3 atmospheres? |
25 mins |
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What is recommended when carboxyhemoglobin concentration exceeds 25%? |
hyperbaric oxygen |
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How is carbon monoxide detected? |
gas chromatography and spectrophotometric |
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What is the gold standard in detecting carbon monoxide? |
gas chromotography |
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Why do neonates have a falsely high CO readings?
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fetal hemoglobin has different spectral properties from adult hemoglobin |
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What specimens will cause errors when detecting CO? |
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Which toxic agent is colorless, odorless gas when substance ionically bound or complexed with CN- is exposed to acid? |
cyanide |
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What does cyanide do to the body? |
readily crosses all biological membranes and binds to heme iron (Hgb, cytochromes in the mitochondria) and causes uncoupling of oxidative phosphorylation and rapid depletion of ATP |
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What are the clinical symptoms of cellular hypoxia due to cyanide? |
flushing, headache, tachypnea, dizziness and respiratory depression, rapidly to coma, seizure, complete heart block and death if dose is sufficiently large |
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What is the treatment for cyanide poisoning? |
administration of sodium nitrite which results in formation of methemoglobin, which binds and clears CN- thiosulfate can also be administered to enhance clearance via metabolism |
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How is whole blood cyanide analyzed? |
photometric methods: generate hydrocyanic acid, add pyridine, barbituric acid and chloramine T to generate a red complex proportional to CN- concentration ion-selective electrode |
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What is the normal CN- concentration? |
<0.2 ug/mL |
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Individuals become comatose when CN- becomes greater than what dosage? |
>2 ug/mL |
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Concentrations of greater than what of CN- are lethal?
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> 5 ug/mL |
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Chronic low-level exposure to CN- concentrations are evaluated by determining what? |
urinary thiocyanate (SCN-) |
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When the iron of hemoglobin goes from the ferrous (2+) to the ferric (3+) state, it forms what? |
methemoglobin |
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What is wrong with methemoglobin? |
it doesn't bind oxygen |
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Normally, what two enzymes help keep heme iron in the reduced state? |
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What can cause someone to be forming methemoglobins? |
congenital or acquired methemoglobin and drugs |
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How can you treat methemoglobin? |
administration of methylene blue |
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What can cause interference with co-oximeter methods? |
methylene blue and sulfhemoglobin |
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T/F: Spectrophotometric methods are interfered by methylene blue |
False (they don't) |
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Methemoglobin is not stable at ____________, so samples should be _______________. |
Methemoglobin is not stable at room temperature, so samples should be kept on ice.
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Freezing samples results in an increase in what? |
methemoglobin concentration |
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What is the normal concentration of methemoglobin? |
<1.5% |
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If there is about 20% of methemoglobin, what is the body's response? |
blue tint to the skin |
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If there is 20-50% of methemoglobin, what is the body's response? |
dyspnea, exercise intolerance, fatique, weakness and syncope (not enough oxygen) |
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If there is 50-70% of methemoglobin, what is the body's response? |
dysrhythmia, seizure and metabolic acidosis and coma |
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If there is greater than 70% of methemoglobin, what is the body's response? |
lethal |
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What substance is the most often used and abused chemical substance? |
alcohols |
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What are the most common alcohols that are tested for? |
ethanol, methanol, isopropanol and acetone |
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What is the metabolite of isopropanol? |
acetone |
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What is ethanol's pharmacologic action on the body? |
depresses the CNS |
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At less than 50 mg/dL, whatis ethanol's pharmacologic action on the body? |
euphoria and decreased inhibitions |
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At 100-300 mg/dL, whatis ethanol's pharmacologic action on the body? |
disorientation and incoordination |
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At >400 mg/dL, what is ethanol's pharmacologic action on the body? |
coma and death |
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CNS actions influenced by ethanol is more pronounced in what phase? |
absorptive phase |
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What is the statutory limit for operation of a motor vehicle? |
80-100 mg/dL |
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How is ethanol metabolized? |
Ethanol is metabolized by the liver alcohol dehydrogenase to form acetaldehyde which is further metabolized to acetic acid. |
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Males metabolize ethanol at about ____________ whereas females metabolize about ____________. |
males: 15 mg/dL/hr females: 18 mg/dL/hr |
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What is the average elimination rate of ethanol for alcoholics? |
30 mg/dL/hr |
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Ethanol is a teratogen...which means what? |
it affects the fetus development (physical, mental, behavioral and/or learning disabilities) |
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How can methanol be consumed since it's not normally found in alcoholic drinks?
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How is methanol metabolized?
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It is oxidized by liver alcohol dehydrogenase at about 1/10th the rate of ethanol to form formaldehyde, which is rapidly metabolized to formic acid. |
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What can formic acid cause? |
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What is the treatment for methanol? |
administration of ethanol (preferential metabolism), and the methanol will be excreted instead of metabolized. |
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What substance inhibits metabolism of methanol? |
4-methylpyrazole |
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What therapy is used to help alleviate the metabolic acidosis? |
sodium bicarbonate therapy |
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What is administered to enhance metabolism of formate? |
folate administration |
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What is used to enhance the clearance of methanol and formate? |
hemodialysis |
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Which alcohol is sold as rubbing alcohol (70%)? |
isopropanol |
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Compare isopropanol to ethanol
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It has twice the CNS-depression activity of ethanol |
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Compare isopropanol to methanol |
Isopropanol is not as toxic as methanol |
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How is isopropanol metabolized? |
It is metabolized rapidly by alcohol dehydrogenase to form acetone |
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Severe isopropanol intoxication is similar to the effects of what? |
ethanol (coma/death) |
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How is isopropanol intoxication treated? |
hemodialysis (NOT therapeutic ethanol administration) |
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What are the requirements for drawing blood from someone for blood alcohol analysis?
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What is a head space analysis? |
Measure the alcohol in the air above the specimen (blood) because alcohol is volatile and will volatilize sufficiently in the air space above the specimen which allows for analysis by GC. |
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Briefly describe how enzymatic analysis is used to detect alcohol |
Alcohol dehydrogenase converts NAD+ to NADH which can be measured at 340 nm |
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Ethanol measurements is used with what to identify presence of methanol, isopropanol or ethylene glycol? |
osmolal gap (sodium, chloride and bicarbonate) determinations |
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List the alcohols in order of shortest retention times to longest
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What are analgesics? |
pain relievers |
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Which analgesics do tylenol belong to? |
acetaminophen |
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What happens when there is an acetaminophen overdose? |
severe liver damage (toxicity or death) |
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What is another less common finding with acetaminophen overdose?
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nephrotoxicity (kidney damage) |
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What is the initial clinical findings for acetaminophen overdose?
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nausea, vomiting and abdominal discomfort |
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Hepatic necrosis does not occur until how many days after ingestion? |
3-5 days |
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What is measured to assess severity of the overdose? |
serum acetaminophen levels |
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Why does acetaminophen overdose take a long time to cause damage? |
It's not the acetaminophen itself that causes the damage, it's the metabolites |
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How is acetaminophen metabolized? |
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How is acetaminophen detected?
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assays (photometric and immunoassays) |
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What are the two major analgesics analyzed in the laboratory? |
acetaminophen and aspirin |
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What is the metabolite of aspirin? |
salicylate |
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Aspirin interferes with what? |
platelet aggregation (prolongs bleeding time) |
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What is acetylsalicylic acid?
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aspirin |
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What is the half life of aspirin? |
15 minutes |
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How is aspirin metabolized?
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It is hydrolyzed to salicylate and is then conjugated with glycine to form salicyluric acid with glucoronic acid to form phenol and acyl glucoronides and some are hydroxylated to form gentisic acid. |
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What is the physiological effect of salicylates? |
it stimulates the central respiratory center and causes hyperventilation and respiratory alkalosis enhances anaerobic glycolysis and inhibit TCA cycle and transaminases, resulting in a build up of organic acids, leading to metabolic acidosis |
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What happens when there is a salicylate overdose in children under 4? |
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What happens when there is a salicylate overdose in children over 4 to adults? |
respiratory alkalosis predominates (exept in severe toxicity), which progresses to metabolic acidosis |
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How is salicylate measured? |
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The initial effects of ethylene glycol resembles what? |
ethanol |
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How is ethylene glycol metabolized? |
It is metabolized to form acid metabolites, including oxalic acid and glycolic acid. |
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How does ethylene glycol cause toxicity in the body? |
It doesn't...it is the metabolites that are responsible for the toxicity. |
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What does ethylene glycol poisoning do to the body? |
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What is the half life of ethylene glycol?
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3 hours |
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What is used to measure ethylene glycol? |
GC |
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The patient has what type of poisoning if their serum osmolal and anion gaps are increased and a decreased serum calcium? |
ethylene glycol |
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Calcium oxalate crystals in the urine and tissues indicate what substance poisoning? |
ethylene glycol |
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Which toxic metal is the most commonly found in the laboratory?
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lead
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How is someone exposed to lead? |
paints (before 1970) |
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What can be seen in the blood if someone has lead poisoning? |
basophilic stippling |
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Lead poisoning in children significantly decreases what? |
intellectual ability |
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What are the methods used for toxic metal analysis? |
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How is drug screening tests performed? |
1. controls on test pad 2. urine goes in the sample wells 3. antibodies in the test bind to the drugs in urine (no line) so it wouldn't bind to the drugs attached to the pad |
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Which drugs are the CNS stimulants? |
amphetamines and cocaine |
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Which drugs are the CNS depressants? |
barbiturates, benzodiazepines and morphine |
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CNS stimulates __________ and depress ______. |
heart rate & respiration and depress appetite |
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CNS depressants ___________ and reduce ________. |
lower heart rate and respiration and reduce pain |
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Which drugs are hallucinogens? |
cannabinoids and PCP |
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Which drugs are antidepressants? |
lithium and tricyclic antidepressants |
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What does amphetamine/methamphetamine do to the body? |
produce initial euphoria, feeling of increased well-being, self-esteem and heightened mental and physical capacity, restlessness, irritability and paranoia |
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Which drugs are a muscle relaxant, anti-convulsant properties, sedative hypnotic, and more likely to occur in individuals who abuse other drugs or alcohol? |
benzodiazepines |
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Which drugs are sedative and hypnotic properties and have been replaced by safer benzodiazepines? |
barbiturates |
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Which drug is the most often used illegal drug? |
cannabinoids (marijuana) |
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Which drug is being used to treat anorexia and nausea in AIDS, chemotherapy and glaucoma patients? |
marijuana |
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What is the principal psychoactive cannabinoid? |
THC |
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How is marijuana metabolized? |
Absorbed rapidly in lungs, peaks in bloodstream within minutes, rapid decline in blood due to distribution into tissues (brain, fat and muscle). The metabolites slowly released from the tissue so may test positive for 2-10 days. |
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What can be a concern with testing for cannabinoids? |
Passive inhalation may produce a positive test but usually not due to a higher cutoff level |
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Which drug elicits a state of increased alertness and euphoria and produces tachycardia and hypertension, hyperthermia, agitation, seizures, coma and death? |
cocaine |
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Which drug produces perceptual distortion of colors, sound, distance, shape, depersonalization and loss of body image and rapidly changing emotions from ecstasy to depression or paranoia? |
LSD |
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Which drug's most common adverse effects are panic attacks? |
LSD |
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Which drug has morphine-like properties? |
opioids/opiates |
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Opium is the dried, milky jice from what plants? |
poppy plants |
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Heroin is a semi-synthetic derivative of morphine from what substance?
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opiates |
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What substance cause sedation, euphoria, respiratory depression, diminished intestinal motility, nausea and vomiting?
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opiates |
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It's not the heroin but its ______________ that rapidly converted to 6-acetylmorphine and then to morphine.
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metabolite |
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Which drug has stimulant, depressant, hallucinogic and analgesic properties with effects including euphoria, hypertension, tachycardia, muscle rigidity, hallucinations and related deaths are most often due to accidental or intentional trauma? |
PCP |
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10-15% of what drug is excreted unchanged in the urine? |
PCP |
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People will try to dilute their urine samples with what? |
detergent and bleach |
