Outline the differences in the assessment and management of poisoning from substance ingestion in the following clinical scenarios, compared with a healthy young adult:
a) 2-year-old child. (30% marks)
b) 30-week gestation pregnant female. (35% marks)
c) 75-year-old adult with chronic kidney disease. (35% marks)
- Ingested agent likely to be non-pharmaceutical
- Vast majority of ingestions are benign
- Other children may be affected (siblings, playmates)
- Doses ingested likely to be small (2-3 tablets or small handful) and toxic effects mg/kg the same as adults but some agents can be potentially lethal for a toddler if even 1-2 tablets taken (e.g. amphetamines, Ca channel blockers, sulphonylureas) or a mouthful (e.g. organophosphate insecticides, eucalyptus oil, one mothball)
- Unlikely to obtain accurate dosing history – risk assessment and management based on “worst-case scenario”
- Need admission to health care facility with resources for paediatric resuscitation
- Regular check of blood sugar levels
- Usual toxicology screening tests for adult patient not necessary
- GI decontamination with activated charcoal is not routine because of increased risks with aspiration – reserved for severe or life-threatening poisoning where supportive care or antidote treatment alone is inadequate
- If severe intoxication suggesting large, repeated or unusual exposure, consider NAI
30/40 pregnant female
- Risks to mother and foetus
- Pregnancy-induced physiological changes impact on drug pharmacokinetics
- Delayed gastric absorption and GI transit time slows drug absorption and increases period of potential benefit for decontamination
- Increased blood volume increases VD and decreases drug plasma levels
- Dilution of plasma proteins increases free drug levels
- Hepatic enzyme systems altered by circulating hormones
- Increased cardiac output increase renal blood flow and GFR
- Hypovolaemia and respiratory compromise may go unrecognised until at a late stage
- A few agents pose increased risk to foetus and treatment threshold is lowered (e.g.
- salicylates, CO, lead, MetHb-inducing agents)
- Excellence in supportive care for the mother ensures best outcome for foetus
- Obstetric and neonatal as well as toxicology input needed including decision for emergency delivery of baby.
75-year-old with CKD
- Limited physiological reserve, deteriorating cognition, multiple co-morbidities and polypharmacy lead to exaggerated and unpredictable response in poisoning
- More severe clinical course for same dose of same agent taken by healthy young adult
- Pharmacokinetic changes with ageing and CKD o Delayed GI absorption o Decreased protein binding and increased free drug levels o Reduced liver function with decreased drug metabolism o Reduced renal function and reduced elimination o Baseline CKD likely to be made worse o “Therapeutic” drug doses may be toxic
- Pharmacodynamic differences from drug effects on impaired organs e.g. poor ability to respond to CVS, respiratory and CNS depressant agents
- Greater incidence of complications e.g. delirium, pneumonia, thrombo-embolism
- Longer ICU and hospital stay
This is another one of the questions in this paper which had a 0% pass rate. Locally available resources include the following chapters:
- Pharmacology and toxicology of childhood
- Pharmacology and toxicology of pregnancy
- Pharmacology and toxicology of old age
The answer would probably work better as a table:
|Pattern of poisoning||
|Differences in approach||
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Barry, J. Dave. "Diagnosis and management of the poisoned child." Pediatric annals 34.12 (2005): 937-946.
Reid, David HS. "Treatment of the poisoned child." Archives of disease in childhood 45.241 (1970): 428.
Henretig, Fred M. "Special considerations in the poisoned pediatric patient." Emergency medicine clinics of North America 12.2 (1994): 549-567.
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Goldfranks Manual of Toxicologic Emergencies: 2007 Edition, Ch. 30: "Reproductive and Perinatal Principles"
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Jansen, Paul AF, and Jacobus RBJ Brouwers. "Clinical pharmacology in old persons." Scientifica 2012 (2012).
Sotaniemi, Eero A., et al. "Age and cytochrome P450-linked drug metabolism in humans: an analysis of 226 subjects with equal histopathologic conditions." Clinical pharmacology and therapeutics 61.3 (1997): 331-339.
Mitchell, Rebecca J., et al. "Dementia and intentional and unintentional poisoning in older people: a 10 year review of hospitalization records in New South Wales, Australia." International Psychogeriatrics 27.11 (2015): 1757-1768.
Rogers, Jody J., and Kennon Heard. "Does age matter? Comparing case fatality rates for selected poisonings reported to US poison centers." Clinical toxicology 45.6 (2007): 705-708.
Doak, Martin W., et al. "Self-poisoning in older adults: patterns of drug ingestion and clinical outcomes." Age and ageing 38.4 (2009): 407-411.