Toxicology

Question 1

Anticholinergic Toxidrome

Answer 1

“Red as a beat. Dry as a bone. Hot as a hare. Blind as a bat. Mad as a hatter. Full as a flask.”
Clinical presentation of anticholinergic toxicity
- Anhidrosis
- Anhidrotic hyperthermia/
- Nonreactive mydriasis. Dilated pupils and blurred vision.
- Delirium and hallucinations\
- Agitated
- Seizures
- Reduced urination
- Sinus Tachycardia (May have prolonged QRS and in some cases progress to Torsades De Pointes, VT or VF)
- Decreased or absent bowel sounds

Question 2

Anticholinergic Toxidrome - Pre-hospital Management

Answer 2

Pre Hospital

• Begin by stabilizing airway, breathing and circulation (DRABC). If necessary ventilate and commence CPR.
• Vital Signs – ECG, SpO2, HR, RR, Temp, EtCO2, BP (Monitor ECG and SpO2)
• IV Access
• Supplemental Oxygen
• Sodium Bicarbonate for prolonged QRS
• Magnesium Sulphate for Torsades De Pointes
• Active cooling – Ice packs, exposing, fluids – for severe hyperthermia
• IV fluids in boluses of 250-500mL for hypotension

Question 3

Anticholinergic Toxidrome - Definitive Management

Answer 3

Antidote - Physostigmine. Dose 0.5-2mg IV

• Usually not required. Most cases can be managed well with supportive cares
• Other Hospital management: Benzodiazepines and GI decontamination with activated charcoal

Question 4

Cholinergic Toxidrome

Answer 4

SLUDGE: Salivation, lacrimation, urination, defecation, gastric emesis (vomiting)
BBB: Bronchorrhea, bronchospasm, bradycardia
- Nicotinic effects - muscle weakness, paralysis
- Cardiac issues - arrhythmias such as heart block and QTc prolongation, ST changes
- Respiratory failure, CNS depression, seizures, lethargy, coma

Question 5

Cholinergic Toxidrome - Managemetn

Answer 5

Benzodiazepines
Supportive cares
Atropine
Cooling
Sedaton

Question 6

Serotonergic Toxidromes

Answer 6

• Altered mental status
• Increased muscle tone
• Hyperthermia
• Hyperreflexia
• Rigidity
• Tremors

Question 7

Serotonergic Toxidromes - Management

Answer 7

• Benzodiazepines – to control seizures
• Supportive care
• Cooling
• Sedation

Question 8

Serotonergic Toxidromes - Pathophysiology

Answer 8

• Either increase serotonin production/release or inhibit serotonin reuptake
• SSRIs block reabsorption of serotonin into the pre-synaptic nerve leading to increase of circulating serotonin in the synapse

Question 9

Serotonergic Drugs

Answer 9

MAOIs, SSRIs, TCAs and some migraine medications

Question 10

Anticholinergic Drugs

Answer 10

Atropine, Tricyclic antidepressants antihistamines, antispasmodics, typical antipsychotics, some parkinsons medications

Question 11

Cholinergic Drugs

Answer 11

Nerve gas
Some pesticides (organophosphates)
Can be found in some household products

Question 12

Sympathomimetic Drugs

Answer 12

Adrenaline
Cocaine
MDMA (ecstacy)
Ritalin
Caffeine
Pseudoephedrine
Moclobemine
Venlafaxine
Amphetamines

Question 13

Sympathomimentic Toxidrome

Answer 13

Sympathetic activation - agitation, mudriasis (dilated pupils), diaphoresis, tremor, tachycardia, hypertension
Cardiovascular - arrhythmias, ACS, aortic dissection, pulmonary oedema
Neurological - intracranial haemorrhage, seizures, psychiatric, agitation, aggression, psychosis
Psychiatric - agitation, aggression
Other - multi-organ fialure, hyperthermia, rhabdomyolysis, hyponataemia

Question 14

Sympathomimentic Toxidrome - Pathophysiology

Answer 14

Release of dopamine, epinephrine, norepinephrine and serotonin

• Norepinephrine causes vasoconstriction by stimulation of alpha-adrenergic receptors on smooth muscle
• Epinephrine increases myocardial contractility and heart rate by stimulation of beta1-adrenergic receptors
• Reuptake of stimulatory neurotransmitters inhibited
• Local anaesthetic - slow nerve impulses by blocking sodium across cell membranes into neuronal pain fibres

Question 15

Sympathomimentic Toxidrome - Management

Answer 15

• Manage ACS, seizures and hyperthermia accordingly
• Oxygen
• IV access
• Midazolam (benzodiazepines very effective) for severe agitation and to sedate
• Consider analgesia
• Options for further management: (not pre-hospital protocol as of yet) Sodium bicarbonate for QRS widening, GTN for hypertension and diazepam for hypertension

Question 16

Sympathomimetic Toxidrome - key points

Answer 16

rapid sedation with benzodiazepines manages most symptoms
hyperthermia is a high-risk sign
DO NOT give beta-adrenergic agonists as they can cause hypertension

Question 17

Opioid Toxidrome

Answer 17

o	Constricted pupils
o	Sedation/ CNS depression
o	Respiratory depression
o	Hypothermia
o	Skin necrosis
o	Compartment syndrome
o	Aspiration
o	Bradycardia and hypotension
o	Decreased bowel sounds

Question 18

Opioid Drugs

Answer 18

	Heroin 
	Morphine
	Fentanyl 
	Pethidine
	Oxycodone
	Codeine
	Tramadol
	Benzodiazepines

Question 19

Opioid Toxidrome - Management

Answer 19

Oxygen
IPPV
Naloxone (1.6mg single dose, IV 50 mcg PRN)