Overdose

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Overdose

Epidemiology

  • 100,000 hospital admissions a year
  • 5% of all acute admissions
  • higher prevalence among females
  • 50% of cases also involve alcohol

Risk factors

  • chronic illness
  • unemployed
  • widowed, divorced or separated
  • alcoholism or drug addiction

Presentation

  • pyrexia
    • anti-cholinergics
    • tricyclics
  • coma
    • alcohol
    • benzodiazepines
    • opiates
    • barbiturates
    • tricyclics
  • constricted pupils
    • opiates
    • amphetamines
  • dilated pupils
    • heroin
    • cocaine
    • tricyclics
    • phenothiazines
  • blisters
    • non-specific
  • arrythmias
    • antiarrythmics
    • anticholinergics
    • tricyclics
    • quinine
    • phenothiazines
  • abnormal movement
    • dopamine receptor antagonists
    • phenytoin
    • carbamazepine
    • tricyclics
  • upper motor neurone signs
    • tricyclics

Urgent assessment

  1. clear airway and assess gag reflex; intubate if needed
  2. assess breathing: RR, cyanosis, SaO2,  ABGs, give oxygen
  3. assess circulation: pulse, BP, JVP (CVP), urine output, ECG
  4. cannulate: BM stix, bloods
  5. rapid clinical assessment
  6. Consider diagnostic trial of antidote e.g. naloxone

Investigations

  1. U+Es
  2. Glucose
  3. Plasma osmolarity
  4. Blood drug levels e.g. paracetamol or salicylate levels
  5. Prothrombin time
  6. ABGs
  7. CXR
  8. ECG

Possible results of investigations

  • metabolic acidosis
    • paracetamol
    • salicylates
    • tricyclics
    • ethanol
  • elevated plasma osmolarity
    • ethanol
    • methanol
    • ethylene glycol
  • low PaCO2
    • aspirin
  • low K+
    • beta agonists
    • theophylline
  • high K+
    • digoxin

General management

  • Hypothermia: Space blanket
  • Seizures: correct acidosis, hypoxia, metabolic abnormalities
  • Hypokalaemia: K+ replacement
  • Acidosis: correct hypoxia, NaHCO3
  • Hypoglycaemia: 10% or 50% dextrose

Specific Management: Reduce Absorption

  • Induced emesis: No longer recommended
  • Gastric lavage: If patient presents within 1-2 hours of ingestion (perhaps longer if ingestion of aspirin or tricyclic antidepessants which delay gastric emptying). Do NOT use if ingestion of corrosives or acids.
  • Activated Charcoal: Given orally or via nasogastric tube (give 10 times the amount of drug ingested). Adsorbs drug in the gut. Evidence for efficacy.

Specific management: Enhanced Elimination

  • Multiple dose activated charcoal: Several drugs are eliminated in bile and then reabsorbed in small intestine. Activated Charcoal adsorbs drug in gut and therefore prevents reabsorption and enhances faecal elimination. Can also cause diffusion of drug into gut lumen from circulation by setting up a concentration gradient. Considered for: aspirin, carbamazepine, dapsone, phenobarbitone, quinine, theophyline.
  • Alkaline Diuresis: Rarely considered for salicylates, phenobarbitone.
  • Acid diuresis: Rarely used
  • Peritoneal dialysis, haemodialysis, amd charcoal haemoperfusion: Used  rarely

 Specific Management: Antidotes

  • arsenic
    • dimercaprol
  • benzodiazepines
    • flumazenil
  • beta-blockers
    • atropine
    • isoprenaline
    • dobutamine
    • glucagon
  • cyanide
    • dicobalt
    • editate
    • sodium nitrite
    • sodium thiosulphate
  • digoxin
    • digoxin-specific antibodies
  • Ethylene glycol / methanol
    • ethanol
  • Iron
    • desferrioxamine
  • Lead
    • dimercaprol
    • penicillamine
  • Opiates
    • naloxone 400mg
  • organophosphates
    • atropine
    • pralidoxime mesylate
  • paracetamol
    • N-acetylcysteine
    • methionine
  • thallium
    • prussian blue
  • warfarin
    • FFP
    • vitamin K
    • cholestyramine
 

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