Principles of managing poisoned patients

Question 1

What are the key stages of managing poisoned patient?

Answer 1

history
examination
investigations 
diagnosis 
management

Question 2

What are some key clinical features to look for in the eye of a poisoned patient?

Answer 2

small pupils (miosis) from opiates
Large pupils (mydriasis) from sympathomimetics and anticholinergics
conjunctival haemorrhage - protracted vomiting (or trauma)
jaundice - late presentation of paracetamol od / alcoholic liver disease

Question 3

What are some other key features to look out for in a poisoned patient?

Answer 3

self-harm - slashing injuries
track marks - from IV drug use
injuries suggestive violence/abuse
extensive bruising from long lie - risk of rhabdomyolysis

Question 4

What are the characteristics of rhabdomyolysis ?

Answer 4

hypoxic muscle damage
release of muscle cell contents - creatine kinase, myoglobin, potassium
myoglobin precipitation in the kidney causes renal failure
coca cola urine (due to myoglobin)

Question 5

What investigations are important to carry out in poisoned patients?

Answer 5

oxygen sats - only ABG can tell if hypercapneoa 
12 lead ECG / cardiac monitor
Temp - drugs causing hyperthermia
- cocaine
- amphetamines
- ecstasy
- serotonergic drugs 
- dinitrophenol

Question 6

What blood tests would you check in a poisoned patient?

Answer 6

urea, electrolytes, creatine
glucose
LFTs
clotting - INR
creatine kinase activity
specific drug assays - always save blood and urine
Always important to get these samples early so you don’t miss what drug they’ve taken

Question 7

Why is urine toxicological analysis important?

Answer 7

useful for drugs of abuse screening
unknown overdose in comatose or delirious patient
must be plain sample tube

Question 8

Why is it important to carry out imaging?

Answer 8

aspiration pneumonia

ingested objects - body packers, body stuffers

Question 9

What are the feature clusters / toxidromes of opiates?

Answer 9

coma, miosis, reduced respiratory rate

Question 10

What are the feature clusters / toxidromes of stimulants?

Answer 10

agitation, delirium, mydriasis (pupil dilation), hyperthermia, tachycardia, arrhythmias

Question 11

What are the feature clusters / toxidromes of salicylates?

Answer 11

nausea, vomiting, tinnitus, deafness, sweating, hyperventilation, metabolic acidosis
- symptoms often confused with sepsis

Question 12

What are the feature clusters / toxidromes of TCA (antidepressants)?

Answer 12

coma, hypertonia, mydriasis, tachycardia

convulsions and cardia arrhythmias with severe TCA

Question 13

What are the feature clusters / toxidromes of methanol/quinine?

Answer 13

blindness, also N+V and tachycardia

Question 14

What are the aims of managing poisoned patients?

Answer 14

symptomatic relief and support
reducing absorption
enhancing elimination
specific antidotes

Question 15

What is involved in gastric lavage?

Answer 15

very rarely undertaken
potential benefit only within 1 hour of ingestion
1-2L of tepid water into stomach and aspiration of fluid out of the stomach

Question 16

What is involved in single dose activated charcoal ?

Answer 16

for patients presenting within one hour of a substantial overdose
not used for alcohol, glycols, acids/alkalis, iron or lithium

Question 17

What is involved in whole bowel irrigation?

Answer 17

body packers
it is a means of reducing absorption
occasionally sustained release preparations
2L per hour orally until bowel effluent clear for 3-4 consecutive hours

Question 18

What is involved in multiple dose activated charcoal?

Answer 18

Enhances elimination of absorbed drug by gastrointestinal dialysis
totally distinct to single dose AC for reducing absorption
evidence of benefit in patients poisoned with carbamazepine, quinine, theophylline and dapsone

Bind drug to maintain low concentration of free drug - drug moves from capillaries down concentration gradient into small intestinal lumen

Question 19

What is useful for the treatment of salicylate poisoning?

Answer 19

urine alkalinisation - admin of IV sodium bicarbonate to achieve pH of 7.5-8.5 - promotes salicylate excretion

Question 20

What is extracorporeal elimination?

Answer 20

haemodialysis /haemodiafiltration
poisoning complicated by renal failure
enhances elimination of ethanol, ethylene glycol, methanol, salicylates and lithium
enhances removal of toxins as it can cross semi-permeable

Question 21

What is useful for heavy metal poisoning ?

Answer 21

chelating agents

sodium calcium edetate for Pb

Question 22

What are some specific antidotes?

Answer 22

acetylcysteine - glutathione precursor for paracetamol poisoning
naloxone - opiate antagonist
flumazenil - GABA antagonist for benzodiazepine poisoning