Toxicology Flashcards
How is acute paracetamol overdose managed when less than 1 hour since time of ingestion?
- Activated charcoal
- Measure serum paracetamol level within 4-8 hours of ingestion
- Plot serum paracetamol level on normogram
- If UNDER normogram line - no medical rx required
- If OVER normogram line - Commence NAC infusion (usu. over 20 hours)
How is acute paracetamol overdose managed when between 1-8 hours since time of ingestion?
- Measure serum paracetamol level within 4-8 hours of ingestion
- Plot serum paracetamol level on normogram
- If UNDER normogram line - no medical rx required
- If OVER normogram line - Commence NAC infusion (usu. over 20 hours)
How is acute paracetamol overdose managed when more than 8 hours since time of ingestion?
- Commence NAC infusion immediately
- Measure serum paracetamol level and ALT
- Plot serum paracetamol level on normogram
- If UNDER normogram line/more than 24 h post OD and ALT normal - stop NAC. If UNDER normogram line/and ALT abnormal - continue NAC infusion until ALT normal
- If OVER normogram line, continue NAC infusion, and check ALT at end of infusion - if not normal, continue NAC, if normal, no further things to do.
How is paracetamol overdose treated when the time of ingestion is unknown?
Follow more than 8 hours scenario
- Commence NAC infusion immediately
- Measure serum paracetamol level and ALT
- Plot serum paracetamol level on normogram
- If UNDER normogram line/more than 24 h post OD and ALT normal - stop NAC. If UNDER normogram line/and ALT abnormal - continue NAC infusion until ALT normal
- If OVER normogram line, continue NAC infusion, and check ALT at end of infusion - if not normal, continue NAC, if normal, no further things to do.
How are multiple/”staggered” paracetamol overdoses treated?
Treat according to time of ingestion of first dose
What should be considered when administering NAC in a paracetamol overdose?
NAC anaphylactoid reactions are common!
Slow infusion + antihistamine if flushing, urticaria occurs
If significant anaphylactic reaction (angioedema, hypotension), cease infusion
List 6 signs of clinical envenomation
Muscle paralysis Coagulopathy Hypotension Rhabdomyolysis/renal failure Vomiting Abdo pain
What first aid measures should be instigated when dealing with a snake bite? (3)
- Pressure immobilisation bandaging - start distally, note location of bite (don’t wash venom) and mark bandage at this point so swabs can be taken later. +/- splint
- Keep patient still
- Call ambulance
What lab tests should be ordered for a suspected snake bite? (7)
- FBE for anaemia, thrombocytopaenia
- UEC
- Coag profile - INR, APTT, fibrinogen, fibrinogen degradation products, D-dimer
- CK for rhabdomyolysis
- Blood group and cross match
- Urinalysis for myoglobin
- Sample for venom detection kit
How is a sample for a snake venom detection kit taken?
Swab at the bite site (cute a window in bandage) and urine sample
What is the role of a snake venom detection kit?
Helps to indicate correct monovalent antivenom to use in an envenomed patient - does NOT help to determine whether or not a patient is envenomed
When should a bandage be removed (snakebite)?
Only once antivenom has been administered - clinical signs of improvement. Re-apply if patient’s condition worsens.
What test results do you see in venom-induced consumptive coagulopathy and which snakes can cause this? (3)
Immeasurably high INR and aPTT with an unmeasurable fibrinogen and positive D-dimer. Brown snakes, tiger snakes and taipans.
What does alcohol withdrawal look like? (3)
- CNS hyperactivity syndrome: tremor, sweating, anxiety and agitation and distractibility
- Tonic-clonic fits
- Severe: delirium tremens
What occurs in delirium tremens? (4)
Hyperactivity
Fluctuating confusion
Paranoid ideation
Visual hallucinations
How would you manage alcohol withdrawal syndrome? (4)
- Diazepam
- Thiamine
- Haloperidol if required
- Non-pharmacological: low-stimulus environment, put patient closer to nurse’s station, re-orient regularly, safety mats under bed
What are the features of opiate intoxication and overdose? (3)
- Presents as stupor or coma - respiratory depression, bradycardia and hypotension
- Pupillary constriction characteristic
- Traumatic muscle necrosis due to prolonged recumbency –> rhabdomyolysis-like picture –> renal failure potentially
What are the features of opiate withdrawal? (4)
- Overwhelming craving for 2-3 days
- Restlessness and symptoms resolving influenza (nasal stuffiness, rhinorrhoea, lacrimation, hot and cold flushes, muscle aching and cramps)
- Later - N&V, abdo cramps and diarrhoea
- Pupillary dilatation characteristic
What are the features of cocaine intoxication?
COCAINE = PSYCHOSTIMULANT
Sympathetic overdrive: tachy, hand tremor, HTN, fever, pale sweating skin
DILATED PUPILS
What are the features of cocaine withdrawal?
Lethargy, inanition and depression
Psychosis can occur after acute and chronic use
How is opioid dependence managed? (2)
- Substitution therapy - methadone, administered once a day under supervision at a clinic/pharmacy OR buprenorphine
OR
- Abstinence-oriented therapy (initial detoxication followed by rehabilitation) - naltrexone
How can opiate withdrawal symptoms be controlled? (4)
- Clonidine
- Octreotide
- Anti-emetics
- Analgesics
List 3 drugs that can be used in alcohol detoxification therapy.
- Naltrexone - blocks euphoric effects of alcohol
- Acamprosate - suppresses craving
- Disulfiram - Aldehyde dehydrogenase inhibitor - causes ‘Asian flush’ symptoms BUT can be potentially fatal!
What are the signs of acute lithium toxicity?
- GI: nausea, vomiting, diarrhoea
- Cardiac: arrhythmias
- Neurologic: ataxia, confusion, neuromuscular excitability, seizures if severe
DIABETES INSIPIDUS IN CHRONIC TOXICITY
How is lithium toxicity managed?
No antidote
- Supportive therapy - fluids, electrolyte imbalance correction
- Haemolysis - reserved for those with established renal failure and those with signs of neurotoxicity
How is cocaine intoxication treated?
- IV sodium bicarb for arrhythmias
- IV diazepam
- phentolamine/vasodilators for severe hypertension
- cooling
Which two Australian spiders are capable of causing death or significant systemic illness?
Red-back and funnel-web spiders
Tick bite clinical signs
Resembles Guillain - Barre syndrome - ticks inject a toxin that causes flaccid paralysis after 3-5 days of feeding in humans
First aid involve in box jellyfish sting
Remove victim from water, douse tentacles with vinegar, remove them
Clinical signs box jellyfish sting
immediate intense pain and envenomation from which death can occur in minutes (probably due to neurotoxic effects causing apnoea and direct cardiotoxicity)
