Management of Poisoning

Question 1

Carbon Monoxide

Answer 1

100% oxygen
hyperbaric oxygen

Question 2

Salicylate

Answer 2

IV bicarbonate
Haemodialysis

Question 3

Lead poisoning

Answer 3

Dimercaprol
Calcium edetate

Question 4

Ethylene glycol or methanol

Answer 4

1st Line: Fomepizole (inhibits alcohol dehydrogenase)

2nd Line: Ethanol

Haemodialysis

Question 5

Why does carbon monoxide poisoning cause tissue hypoxia?

Answer 5

binds readily to haemoglobin, forming carboxyhaemoglobin

→ reduced oxygen-carrying capacity

Question 6

Symptoms of carbon monoxide poisoning

Answer 6

headache: 90%
nausea + vomiting: 50%
vertigo: 50%
confusion: 30%
weakness: 20%

severe toxicity:
‘pink’ skin and mucosae, hyperpyrexia
arrhythmias
extrapyramidal features

Question 7

What level of carboxyhaemoglobin on a blood gas would make you worry about carbon monoxide poisoning?

Answer 7

10 - 30% = symptomatic
> 30% = severe toxicity

Normal levels:
< 3% non-smokers
< 10% smokers

Question 8

Management of corrosive substance ingestion

Answer 8

ABCDE
- ?airway swelling/ compromise
- look for peri-oral oedema

• High dose IV PPI
• do not try to neutralise with other substance
• Surgical ref if ?perforation
• Upper GI scope if symptomatic
• Oral fluids and observation if asymptomatic

Question 9

Mechanism of action of cyanide

Answer 9

inhibits cytochrome c oxidase
=> cessation of mitochondrial electron transfer chain

Question 10

Features of cyanide poisoning

Answer 10

‘classical’ features:
- brick-red skin
- smell of bitter almonds

ACUTE: hypoxia, hypotension, headache, confusion

CHRONIC: ataxia, peripheral neuropathy, dermatitis

Question 11

Management of cyanide poisoning

Answer 11

Supportive measures:
- 100% oxygen

Definitive:
- hydroxocobalamin IV
- combination of amyl nitrite (inhaled), sodium nitrite (IV), and sodium thiosulfate (IV)

Question 12

What is the chemical name for coolant/anti-freeze?

Answer 12

Ethylene glycol

Features of toxicity are divided into 3 stages:

Question 13

Stages of ethylene glycol toxicity

Answer 13

Stage 1: similar to alcohol intoxication: confusion, slurred speech, dizziness

Stage 2: metabolic acidosis with high anion gap.
Also tachycardia, hypertension

Stage 3: acute kidney injury

Question 14

Features of Mercury poisoning

Answer 14

paraesthesia
visual field defects
hearing loss
irritability
renal tubular acidosis

Question 15

Features of methanol poisoning

Answer 15

similar to alcohol - intoxication, nausea

visual problems - blindness.
?secondary to accumulation of formic acid

Question 16

Management of methanol poisoning

Answer 16

1. Fomepizole (competitive inhibitor of alcohol dehydrogenase)
2. Ethanol
3. Haemodialysis

Question 17

Mechnanism of organophosphate poisoning

Answer 17

inhibition of acetylcholinesterase

=> upregulation of nicotinic and muscarinic cholinergic neurotransmission

Question 18

Features of oragnosphosphate poisoning

Answer 18

Accumulation of ACh
=> opposite of ANTIcholinergic symptoms

Salivation
Lacrimation
Urination
Defecation/diarrhoea
hypotension/ bradycardia
small pupils
muscle fasciculation