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5 Cards in this Set
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Regarding different biological samples T/F
1. blood - usually only for specific drug levels 2. urine and sweat may be used for drug screening 3. hair / skin - usually only to diagnose chronic toxicity (e.g. arsenic) 4. saliva - concentrations of drugs are usually higher than in urine; may be able to estimate serum concentration if salivary concentration known 5. meconium - can detect intrauterine toxic exposure |
1. T
2. T 3. T 4. F - concentrations LOWER |
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What are the (formal blood) drug levels that may assist risk assessment or management? Which is the only one appropriate as a screening test in unknown ingestions??
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CBZ
Digoxin Ethanol, Ethylene glycol Iron Lithium Methanol, Methotrexate Paracetamol (can be used for screening), Phenobarb Salicylate Theophylline Valproate |
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Chemical urine spot tests - which drugs?
NB they are qualitative, provide results in <20/60, have low sens and spec. |
- paracetamol
• salicylates - trinders spot test • FPN test for phenothiazines • opioids • barbiturates • benzodiazepines • benzoylecgonine • phencyclidine • THC |
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What are the limitations of testing levels in the ED; what are the indications?
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ADDITIVE VALUE OF TESTS
• 95% of ingested drugs can be suspected by hx, exam, other ix • the frequency of useful unexpected results is only 0.9% in paediatric patients • may assist with decision for antidotes - rarely indicated without: - specific clinical features being present - measurement of blood levels LIMITATIONS OF TESTS • does not confirm detected agent is responsible for toxicity • results usually take too long to be useful in the ED • expensive • few clinical decisions made as a result • may detect metabolites from previous non relevant ingestion e.g. THC metabolites excreted for 2 weeks, cocaine • false negatives common following ingestions of clonazepam and lorazepam - neither metabolised to oxazepam which most toxicology testing depends on for detection INDICATIONS • rarely indicated in ED • severe toxicity and unknown ingestion • most useful in - patients with unexplained behavioural disorders - new onset seizures - covert ingestions (e.g. diuretic use in eating disorders) |
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Check out Dunn 1324 - lots of data on different methods of lab analysis of toxins, but I'm unsure of what value this is to our exam.
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