Poisoning And Overdose Flashcards
Opiates - reversal agent
Naloxone
- competitively binds to opioid receptors causing a blockade
- IV fastest action
- half life of naloxone is much less than that of opioids, so overdose can return once naloxone wears off
Opioids - who is most likely to overdose
Heroin users who have recently been incarcerated/gone ‘cold-turkey’ and return to heroin use
- take the same dose they were on before cessation, but in the absence of tolerance
Benzodiazepines - clinical features of overdose
Agitation Euphoria Blurred vision Slurred speech Ataxia Slate-grey cyanosis
Benzodiazepines - management
Flumazenil - can act as a reversal agent, but is not always recommended
- reduces sedative/drowsy effect
- half-life much less than that of the benzo’s, so overdose can continue after the reversal agent has worn off
- competitively binds to benzodiazepines
Causes dangerous withdrawal in long-term abusers
Beta-blockers - management
Glucagon
- positively inotropic agents are not in effective management
Correct hypocalcemia with calcium
Cannabis - signs and symptoms of overdose
Dry cough Increased appetite Social withdrawal Paranoia Altered perception of time
Sympathomimetics e.g. cocaine - clinical features of overdose
Tachycardia Mydriasis Euphoria Formication - insects crawling on my skin Agitation Tremor Arrhythmias
Sympathomimetics e.g. cocaine - treatment
Benzodiazepines
Antidotes - common overdoses
Anti-freeze (ethylene glycol) - ethanol Cyanide - dicobalt edetate Lead poisoning - sodium calcium edetate Organophosphate poisoning - atropine Heparin - protamine sulphate
Carbon monoxide - signs and symptoms
Inebriation Coma Hyporeflexia Tachycardia Pulmonary oedema Shock Metabolic acidosis Headache
Carbon monoxide - management
Hyperbaric oxygen
Paracetamol overdose - clinical features
Nausea Vomiting Renal failure - oliguria and metabolic acidosis Hepatic necrosis - jaundice and RUQ pain - encephalopathy - hypoglycaemia Asymptomatic until acute liver failure occurs (24-72 hours later)
Paracetamol overdose - investigations
Paracetamol levels (and salicylate) - accurate over 4 hours after ingestion Bloods - LFTs - PT (indication of acute liver failure) - U&Es - glucose - INR ABG for metabolic acidosis
Paracetamol overdose - management <8 hours after ingestion
Activated charcoal
- if >12g or >150mg/kg ingested
- most effective within an hour of overdose
Acetylcysteine
- promotes conjugation of circulating paracetamol
- only given if plasma paracetamol levels are known, and are above the treatment line
- best effect <12 hours after ingestion
- administration continued for 24 hours regardless of levels
Paracetamol overdose - management >8 hours after ingestion
Acetylcysteine
- if >12g or 150mg/kg ingested (don’t wait for plasma paracetamol levels)
- administer with 5% dextrose
- 5% of patients have an allergic rash
Paracetamol overdose - management >24 hours after ingestion
Consult toxbase and seek expert advice
Aspirin overdose - clinical features
>125mg/kg is not toxic 250mg/kg is mildly toxic - tinnitus - lethargy - dizziness - nausea/vomiting >500mg/kg - dehydration - sweating/warm extremities - bounding pulse - deafness - hyper/hypoglycemia - confusion and disorientation - coma (rare)
Aspirin overdose - life threatening features
Pulmonary oedema
Metabolic acidosis
Salicylate concentration >700mg/l
Aspirin overdose - investigations
Bloods - salicylate concentration (not an indicator of severity - accuracy best >4 hours) - U&Es - glucose - plasma potassium (hypokalaemia likely) Urine pH ABG - metabolic acidosis
Aspirin overdose - measuring severity
Stage 1 - alkalotic blood and alkalotic urine Stage 2 - alkalotic blood and acidotic urine Stage 3 - acidotic blood and acidotic urine
Aspirin overdose - management
Activated charcoal (>125mg/kg ingested <1 hour ago)
Gastric lavage (>500mg/kg ingested <1 hour ago)
Aggressive rehydration
Consider glucose
- intracellular glucose often deplete even when blood glucose is normal
Sodium bicarbonate
- to increase the alkalinity of the urine (increases excretion of salicylate)
- if >500mg/kg ingested
- be aware hypokalemia reduces effectiveness of urine alkalinity
Haemodialysis - for severe cases
Aspirin overdose - indications for haemodialysis
Plasma salicylate >700mg/kg Renal failure Heart failure Coma Convulsions Severe metabolic acidosis (pH <7.2) CNS symptoms continue despite correction of acidosis
