Toxicology

Question 1

What are the King’s College criteria for liver transplant in paracetamol overdose? (5)

Answer 1

1. PH <7.3
2. Cr>300
3. Lactate >3.5 on admission or >3 24 hours post-ingestion or after adequate fluid resus
4. PT>100 seconds
5. Encephalopathy grade 3 or 4 (stupor or coma respectively)

Question 2

How do you calculate an anion gap?

Answer 2

Na - (Cl + HCO3) = 4-12

Question 3

How do you adjust an anion gap in hypoalbuminaemia?

Answer 3

Reduce anion gap by 0.25 per 1g of albumin <40

Question 4

What is the SNAP regimen?

Answer 4

100mg/kg in 200mls 5% dextrose over 2 hours
Then: 200mg/kg in 1L 5% dextrose over 10 hours

Question 5

Normal anion gap met acidosis causes:

Answer 5

CAGE
Chloride
Addisons/Acetazolamide
GI losses - stoma/GI/diarrhoea
Extras - RTA, DKA recovery, oral acidifying salts

Question 6

Raised anion gap met acidosis

Answer 6

CAT MUDPILES
CO/cyanide/CHF
Aminoglycosides (gent etc)
Toluene (glue sniffing), Teophylline
Methanol
Uraemia
DKA/EtOH/starvation Ketosis
Paracetamol/Paraldehyde/Pyroglutamic acidosis
Iron/Isoniazid/Inborn errors of met
Lactic acidosis
Ethylene glycol, Ethanol
Salicylates

Question 7

What are the features of serotonin syndrome?

Answer 7

Tremor, diarrhoea and restlessness are most common.
Others:
Autonomic - tachycardia, hyperthermia, dilated pupils, sweating ++
Neuromuscular - tremor, increased tone, hyperreflexia
D - agitation, confusion

Question 8

What are the common features of TCA OD?

Answer 8

Onset within 1-2 hours:
- anticholinergic
- divergent squint
- increased tone
- up going planters
- acidosis
- seizures/coma

Question 9

What are the ECG changes in TCA OD?

Answer 9

Progressive from:
1. Sinus tachycardia
2. Prolonged PR & QRS
3. Ventricular arrhythmia and Heart block

Note a dominant R wave in aVR and a slurring of the terminal QRS

Question 10

What is the antidote for TCA OD?

Answer 10

Sodium bicarbonate 8.4% 100mls