Toxicology Flashcards
Ethylene Glycol
> 1ml/kg potentially lethal
Severe High Anion Gap Metabolic Acidosis Elevated Osmolar Gap Elevated Lactate Hypocalcaemia - calcium oxalate crystals AKI
Clinical:
CNS - EOTH like effects, coma, seizures
Cardiopulmonary - SOB, tachycardia, tachypnoea, HTN, shock
Renal - flank pain and oliguria
Mx: Sodium Bicarb Intubation and hyperventilation Treat seizures with IV BZD Ethanon - competitive inhibitor of ADH Haemodialysis if: -Large ingestion with Osmolar gap >10 -acidaemia pH <7.3 -AKI -Ethylene glycol level > 8mmol/L
Methanol
> 0.5ml/kg of 100% methanol is potentially lethal
metabolised to formic acid
Severe HAGMA
Elevated Osmolar Gap
elevated Lactate later due to inhibition of cellular oxidate metabolism
CT BRAIN may demonstrate ischaemic or haemorrhagic injury to basal ganglia
Clinical:
Initially ETOH like effects
Latent onset of headache, dizziness, vertigo, visual changes/blindness, Seizure/comas
Mx: Sodium Bicarb INtubation and Hyperventilation Seizures - IV benzos correct hypoglycaemia (cofactor therapy) Folic acid 50mg IV every 6 hours ETOH: 3x 40ml shots 40% vodka then 40ml shot per hour, aim BAL of 100-150mg/dL Haemodialysis: -if treating with ETOH -pH < 7.3 -visual symtpoms -renal failure -Methanol level > 16mmol/L
Amisulpride
Atypical Antipsychotic
Risk > 4g
QT Prolongation, Torsades
Bradycardia - increases risk of torsades
Hypotension
CNS depression
16 hours observation, cardiac monitoring if abnormal ECG
Amphetamines / Sympathomimetics
MDMA/ecstasy, speed/methamphetamines
Severe Hyperthermia ACS / APO / Hypertension Cardiac Dysrhythmias Aortic Dissection Intracranial haemorrhage/SAH Rhabdomyolysis, renal failure SIADH / Hyponatraemia / Cerebral oedema Seizures
mx: AVOID Betablockers titrated Benzodiazepines IV for aggitation/seizures/HTN Refractory HTN: -Phentolamine 1mg IV every 5 minutes -GTN or SNIP infusion -Treat hyponatraemia <120 with 3% saline Manage Hyperthermia with cooling
Children, One Pill Kills
Methamphetamines - agitation, hypertension, hyperthermia Opioids - resp depression, coma CCBs - hypotension, bradycardia BBs - hypoglycaemia TCAs - arrythmias, seizures Chloroquines - prolonged QRS/VT Sulfonylureas - hypoglycaemia Theophylline - SVT, seizures
Serotonin Syndrome - diagnostic criteria
The Hunter diagnostic criteria requires the presence of one of the following categories in the setting of ingested serotonergic medication:
- spontaneous clonus
- inducible clonus + (agitation or sweating)
- occular clonus + (agitation or sweating)
- tremor + hyper-reflexia
- hypertonia and T > 38C + clonus
Anticholinergic Syndrome
•warm, dry skin •mild hyperthermia •dry mucous membranes •mydriasis •tachycardia •urinary retention •absent bowel sounds •central anti-cholinergic syndrome -confusion -hallucinations - usually visual
Common sources •antimuscarinics -benztropine -hyoscine -scopolamine -Trumpet lily / Angel's trumpet / (Brugmansia) -Jimsonweed (Datura stramonium) •antihistamines •tricyclic antidepressants •amanita muscaria mushrooms
Neuroleptic Malignant Syndrome
•idiosyncratic reaction to neuroleptic drugs:
- haloperidol
- fluphenazine
- chlorpromazine
- metoclopramide
- prochlorperazine
Fever Generalised muscle rigidity •catatonia, stupor, coma •Parkinsonian rigidity present in > 90% •often with associated tremor •reflexes decreased or absent •characteristically unresponsive to anticholinergics Autonomic instability •tachycardia •sweating •sialorrhoea •labile BP -pupils usually normal Altered conscious state •ranging from confusion to coma •seizures uncommon
Treatment:
Supportive - cooling, hydration, I+V
Bromocriptine
•dopamine agonist
•2.5 mg orally or via NGT 8 hourly
•increase up to max of 5 mg every 4 hours according to response
•has been useful when combined with dantrolene
Dantrolene
•2-3 mg/kg per day IV up to 10 mg/kg maximum total dose
•probably of little use in neuroleptic malignant syndrome (controversial)
Sympathomimetic Toxidrome
•CNS excitation -agitation -tremor -seizures •hypertension •tachycardia •sweating •mydriasis
Common sources
- amphetamines
- cocaine
- LSD
- caffeine
- theophylline
- phencyclidine
- methylphenidate
Drugs with toxicity on withdrawal
•ethanol •benzodiazepines / barbiturates -tremor -sleep disturbance -depression -seizures •opioids •amphetamines •GHB •beta blockers -hypertension -angina •clonidine -hypertension •SSRIs (short acting only) •valerian •steroids -adrenocorticoid deficiency
Drug Withdrawal toxidrome
•diarrhoea •mydriasis •piloerection -“cold turkey” •tachycardia •lacrimation •abdominal pain •agitation •hallucinations
Serotonin Syndrome Causes
Drugs most commonly responsible
•sertraline (the most common) •other SSRIs •lithium •moclobemide and other MAOI -including methlyene blue and linezolid •LSD •imipramine
Other agents associated with serotonin toxicity
- amphetamines and synthetic stimulants
- pethidine
- fentanyl
- tramadol
- sumatriptan
- dextromethorphan
- chlorpheniramine (chlorphenamine)
- sibutramine (anti-obesity agent)
- citalopram
- tryptophan
- St John’s wort
Serotonin Syndrome Clinical Features
Early features
•agitation
•akathisia
•tremor
•hyper-reflexia
•shivering
•inducible clonus
-especially ocular clonus (distinguishable from nystagmus as no fast component)
- includes a variety of abnormal involuntary fine or coarse oscillations of gaze in all directions (examples (external link))
-can be continuous or triggered by rapid eye movement
-includes “ping pong gaze” (short cycle, periodic, alternating lateral gaze)
-prominent in lower limbs
•repetitive rotation of the head with the neck held in moderate extension
•altered mental state
•sialorrhoea
•active bowel sounds
•diarrhoea
Late features
•tachycardia •mydriasis •sweating •hypertension •hyperthermia •myoclonic jerks •muscular rigidity -mainly in lower limbs -rhabdomyolysis or increase in CK not common
Serotonin Syndrome Treatment
•cyproheptadine
-8 mg initial oral dose then 4 mg 4 hourly
or Phenothiazines:
- olanzapine 5 mg orally / IM
- chlorpromazine 50-100 mg IM/IV then 50-100 mg 6 hourly
•severe hyperthermia
- barbiturates, neuromuscular paralysis for intubation and thermal control
- dantrolene and bromocriptine have been reported to increase CNS serotonin levels and may cause clinical deterioration
Corrosive Airway Injury
Alkalis
Acids
Glyphosate (herbicide)
Paraquat (herbacide)
Ventricular Tachycardia, Fast Sodium channel blockade causes
Chloroquine / Hydroxychloroquine cocaine Flecanide Local Anaesthetics Procainamide Propranolol Quinine TCAs
Prolonged QRS Duration - fast Na channel blockade
Chloroquine / Hydroxychloroquine cocaine Flecanide Local Anaesthetics Procainamide Propranolol Quinine TCAs
Contraindications to Activated Charcoal
Resuscitation not yet complete non toxic ingestion / dose uncooperative patient ALOC without airway protection likely to progress to ALOC / seizure Corrosive ingestion Agent does not bind AC
Dose is 50 g for adults, 1g/kg children
Useful Drug Levels
Carbamazepine Digoxin Ethanol Ethylene Glycol Iron Lithium Methanol Methotrexate Paracetamol Phenobarbitol Salicylate Theophylline Sodium Valproate
Whole Bowel Irrigation
Indications:
- Iron OD > 60 mg/kg
- Slow Release KCL > 2.5 mmol / kg
- Life threatening Slow Release Verapamil or Diltiazem
- Symptomatic arsenic
- Lead ingestion
- Body Packers
Contraindications:
- unable to place NGT
- ileus or bowel obstruction
- ALOC/not ventilated/seizures etc
Dose - PEG
2l/hr adult
25/ml/kg hr child
