Toxiciology Flashcards
What are the features of salicylate poisoning? (6)
- Increased RR
- Tinnitus
- Deafness
- Sweating
- Vasodilation
- Acid base disturbance
What metabolic disturbance do adults presenting with salicylate poisoning predominates?
Reps alkalosis > metabolic acidoses
What metabolic disturbance do children presenting with salicylate poisoning predominates?
Metabolic acidosis > resp alkalosis
What is mild salicylate poisoning and how should it be managed?
- < 300mg/L
- Asymp and normal VBG then home at 6 hours
What is moderate salicylate poisoning and how should it be managed?
- 300-700mg/L
- Urinary alkalization - PH 7.5-8.5 using sodium bicarbonate
What is severe salicylate poisoning?
1, CNS features, acidosis or > 700mg/L
2. Consider HD and I+V
What is the pathophysiology of paracetamol poisoning?
Metabolite of paracetamol (NAPQI) binds glutathione in the liver and causes hepatic necrosis when glutathione stores are depleted.
What are the features of TCA OD in conscious patients? (7)
Anti-cholinergic toxidrome
- Tachycardia
- Dry skin
- Dry mouth
- Dilated pupils
- Urinary retention
- Ataxia
- Jerky limb movements
What signs do unconscious patients developed following TCA OD? (7)
- Divergent squint
- Hypertonia
- Hyper-reflexia
- Myoclonus
- Upgoing plantars
If comatose - areflexia and muscle facciditiy
What ECG changes will be seen in TCA OD and which is the most sensitive?
- Increased QRS (most sensitive)
- Increased PR
- Tachy
- P waves can be lost in T - looks like VT
What is the tx for TCA overdose? (5)
- If under 1 hour activated charcoal
- 50-100ml 8.4% bicarbonate
- Aim PH 7.5-7.55 (excessive is fatal) and normal QRS
- Avoid routine use anti-arrhythmics
- Severe consider glucagon or intralipid
What is the antidote to benzo OD?
Flumazenil
How long does flumezanil last?
1 hour
What are the risks of using flumazenil and when is it particularly high risk?
Can lead to convulsions and arrhythmias
With concurrent TCA OD - can lead to arrest
What signs/symptoms feature in haloperidol + chlorpromazine (and related drugs)?
Oculogyric crisis
Muscle spasms - torticollis/opisthonus
What ECG changes will you see in haloeridol/chlorpromazine/similar drugs in OD? (2)
- Increased QRS
- Arrhythmias
What is the treatment for haloperiol/chlorpromazine OD? (3)
- Proycylidine
- Diazepam
- Bicarbonate if QRS >120ms
What are the features of lithium toxicity? (6)
- n/v
- diarrhoea
- ataxia
- confusion
- increased tone
- clonus
What is the treatment for lithium toxicity?
Supportive
Dialysis
What are the effects of sulfanylurea overdose?
- Low glucose
- Low potassium
What is the treatment for sulfanylurea overdose?
Octreotide
What are the features of unique to propanolol OD? (2)
- Bronchospasm in asthmatics
- Hypoglycaemia in children
What does sotalol OD cause in particular?
Torsades des pointes
What are the treatments of beta blocker OD without severe hypotension?
- Consider activated charcoal
- Atropine may work (pacing probably not)
- Glucagon 5-10mg IV (anticipate vomiting)
In severe beta-blocker OD with low BP what are 3 treatment options?
- High dose Insulin Euglycaemic Therapy (HIET)
- Intralipid
- Ionotropes/vasopressors
What are the features of CCB OD? (6)
- Bradycardia
- AV block
- Profound vasolidation
- Metabolic acidosis
- Hyperkalaemia
- Hyperglycaemia
What is the treatment for CCB OD? (3)
- Consider activated charcoal
- Atropine +/- pacing
- Calcium chloride 10% over 10 mins and consider repeating up to x 4
What are the treatment options for severe CCB OD? (4)
- Glucagon
- Intralipid
- HIET
- Vasopressors/ionotropes
What are the features of digoxin toxicity? (4)
- Xanthopisa- yellow flashes/discolouration
- Hyperkalaemia
- Brady, increased PR/QRS
- Arrhythmias
What is the treatment for digoxin toxicity? (3)
- Digiblind/Digifab
- Insulin/dex for increased K+ (rapid decrease with Digibind)
- Atropine/pacing
What are the biochemical changes in acute methanol poisoning? (3)
- Acidosis
- Hypergylcaemia
- Raised amylase
What are survivors of methanol poisoning at risk of? (2)
- Blindness
- Parkinsonian features
What is the treatment for methanol poisoning? (4)
Ethanol
Fomepizole
Folinic acid
Bicarbonate if acidotic
What are the early (<12 hours) features of ethylene glycol poisoning?
Appear drunk, no smell alcohol
What are the late features of ethylene glycol poisoning? (6)
- CCF
- Acidosis
- Tachy/arrhythmias
- Hypocalcaemia (can be profound)
- Acute tubular necrosis
- CN palsies`
What are the treatment options for ethylene glycol poisoning? (5)
- Fomepizole
- Ethanol
- Sodium bicarbonate for acidosis
- Calcium chloride only if seizures or QTc >500 as can lead to calcium oxolate stones
- HD + I+V
What can occur in petrol ingestion?
Can be fine but aspiration lead to severe pneumonitis requiring steroids + resp support
What is the pathophysiology of organophosphate poisoning?
Inhibit cholinesterases which leads to build up of acetylcholine at nerve endings (cholinergic affect)
What are the features of organophosphate poisoning (cholinergic toxidrome)? (8)
S- alivation
L - acrimation
U - rination
D - efecation
G - I upset
E - mesis
M - iosis
M - muscle twitching
Bradycardia, paralysis and resp failure
What is the treatment for organophosphate poisoning and what is its mechanism
Atropine - blocks affect of acetylcholine at muscarinic receptors
Eases smooth muscle constriction and dries up secretions
What is the atropine dose in organophosphate poisoning?
2mg IV adult
0.02mg/kg children
Every 5 mins double dose until atropinisation
What is the mechanism of pralidoxime?
Reactivate acetylcholinesterase inhibited by organophosphates allowing metabolisation of acetylcholine.
What can lead to cyanide poisoning? (3)
- Polyurethane burning
- Fruit kernels
- Finger polish remover
What are the features of cyanide poisoning? (4)
- Metabolic acidosis
- Seizures
- Pulmonary oedema
- Arrhythmias
What is the initial management of cyanide poisoning? (2)
- Remove clothes
- Wash exposed skinW
What is the antidote for severe cyanide poisoning and what is the risk of giving it?
- Dicobalt edetate - Kelocyanor
- If no cyanide can be fatal
What are the treatments for mild cyanide poisoning? (2)
- Sodium thiosulphate
- Sodium nitrate
What is the best treatment for inhaled cyanide poisoning?
5g hyroxycobalamin IV (Cyanokit)
What is the max dose of lidocaine?
3mg/kg
max 200mg
What is the maximum dose of lidocaine with adrenaline?
7mg/kg
max 500mg
What is the maximum dose of bupivicaine?
2mg/kg
150mg
What is the management of LA toxicity including dose?
Intralipid
1.1.5mg/kg bolus and 15mg/kg/hr infusion
5 mins no response:
2. 2nd bolus and increase infusion to 30mg/kg/hr
3.Continue to 3rd and 4th bolus which is maximum
In arrest may need 1 hour for intralipid to take effect
How are hydrofluric burns managed? (4)
- Irrigate normal saline ++
- Calcium gluconate gel
- Tx low Ca2+
- In arrest - 60ml x 10% calcium chloride
What drugs can cause methaemoglobinaemia?(7)
benzene derivatives
chloroquine
dapsone
prilocaine
metoclopramide
nitrites (nitroglycerin, NO, sodium nitroprusside)
sulphonamides
What are the features of methaemoglobinaemia?
1.cyanosis
2. symptoms and signs of decreased oxygen delivery e.g. chest pain, dyspnea, altered metal state, end organ damage
3. SpO2 reading 85-90%
4. blood samples typically have a chocolate brown hue
5. Normal PaO2
What is the treatment for methaemoglobinaemia?
Methylene blue
What is the triad of symptoms in serotonin syndrome?
- Change in mental staus
- Autonomic hyperactivity
- Neuromuscular manifestations
What are the 3 major and 5 minor symptoms suggestive of neuroleptic malignant syndrome?
Major
1. Fever
2. Rigidity
3. Elevated CK
Minor
1. Tachycardia
2. Abnormal arterial pressure
3. Altered consciousness
4. Diaphoresis
5. Leucocytosis
Describe an anticholinergic toxidrome (8)
- Altered mental status, confusion, restlessness, seizures, coma
Symptoms resulting from peripheral muscarinic receptor blockade:
2. Impaired sweat gland function
3. Dry mouth
4. Dry axillae
5. Mydriasis
6. Tachycardia
7. Flushing
8. Urinary retention
In cases of serotonin syndrome where other management options have failed, what is the treatment?
Cryoheptadine
What are the tx options for NMS? (2)
- Bromocriptine (first line)
- Dantrolene
What are the commonly used drugs in ED that might cause methaemaglobinaemia? (4)
- Metoclopramide
- Nitrites (including ‘poppers’ and GTN)
- Local anaesthetics
- Abx including dapsone
What level of methaemagobinaemia should be treated? (2)
- > 30% methaemaglobin
- Any evidence of tissue hypoxia
If initial management of beta blocker OD with low BP doesn’t success (i.e. glucagon) what does toxbase suggest as second line?
HIET
How is the toxicity of something calculated?
From the Lethal Dose 50 (LD50) = concentration required to kill 50% of exposed individuals
How do cholinergic drugs act?
Class of medication that increase/mimic activity of acetylcholine and lead to parasympathetic activity increase
Name anticholingergic medication? (7)
- Tricyclic antidepressants (amitryptyline)
- oxybutynin
- olanzepine
- quetiapine
- clozapine
- chlorpromazine
- prochlorperazine
What type of toxidrome does Sarin gas cause?
Cholinergic
Over what level does acute radiation syndrome?
> 0.5 Sv (Sievert)
What are the paeds ‘one pill killers?’ (8)
- Beta blockers
- Calcium channel blockers
- Opiates
- Amphetamines
- Theophylline
- Sulfonyureas
- TCAs
- Chloroquines