Drug Overdose Flashcards
What are some clinical features of opiate overdose (heroin and prescribed opiates)?
Pinpoint pupils
Reduced HR
Reduced RR
Reduced GCS
What are some clinical features of anticholinergic overdose (tricyclics)?
Hyperthermia
Agitated/hypervigilant
Dilated pupils
Drug flushed skin
Tachycardia
Hypertension
Urinary retention
What are some clinical features of cholinergic overdose (organophosphate pesticides and some mushrooms)?
Confusion
Miosis
Bradycardia or tachycardia
SLUDGE (salivation, lacrimation, urination, diarrhoea, GI upset, emesis)
What are some clinical features of sympathomimetic overdose (cocaine, amphetamines, MDMA, caffeine)?
Tachycardia
Hypertension
Hyperthermia
Agitation
Mydriasis
Diaphoresis
What are some clinical features of sedative/hypnotic overdose (benzodiazepines, barbiturates, anxiolytics/sleeping tablets)?
Bradycardia
Hypothermia
Reduced RR
Reduced GCS
What amount of ingested paracetamol is considered at risk?
> 75mg/kg
What 3 factors predispose to paracetamol toxicity?
1) Quantity ingested
2) Glutathione deficiency
3) Enhanced cytochrome p450 system
What is the pathophysiology of paracetamol overdose?
Toxicity caused by toxic metabolite N-acetyl-P-benzoquine imine (NAPQI)
Insufficient quantities of glutathione to conjugate NAPQI causes hepatic necrosis, failure and death
N-actylcysteine (antidote) maintains glutathione levels
What are some clinical features of paracetamol overdose?
Nausea
Vomiting
Abdominal pain
What amount of ingested aspirin causes salicylate poisoning?
125mg/kg = mild toxicity
>250mg/kg = moderate toxicity
500mg/kg = severe/fatal toxicity
What is the pathophysiology of aspirin/salicylate overdose?
Aspirin is absorbed from stomach and small intestine and converted by plasma enterases to active metabolite salicylic acid
Salicylic acid causes respiratory alkalosis and metabolic acidosis
What are some clinical features of salicylic/aspirin poisoning?
Nausea and vomiting
Tinnitus
Epigastric pain
Sweating
Haematemesis
Tachypnoea
Tachycardia
Pyrexia
Sweating
Non-cardiogenic pulmonary oedema
Reduced conscious level/seizure
What are some clinical features of carbon monoxide poisoning?
Shortness of breath
Tachycardia
Neurological signs
Reduced consciousness
Seizures
Headache
Malaise
Lethargy
Nausea
Cherry red discolouration of lips and mucous membranes (terminal poisoning)
What are some investigations for suspected drug toxicity?
A-E approach
ECG (prolonged QTc/arrhythmia)
Bloods
- Paracetamol done at least 4 hours after ingestion
- Salicylate levels checked at least 2 hours post ingestion if symptomatic or 4 hours is asymptomatic
ABGs (raised anion gap metabolic acidosis)
What is the management of drug toxicity?
Usually conservative management
IV fluids for hypotension
Supplementary O2 (especially CO poisoning)
Airway support
Treat seizures
Specific antidotes
Activated charcoal solution given within 1 hour of ingestion (50g adults 1g/kg for children)
Urinary alkalinisation, haemodialysis, haemofiltration
