Toxicology

Question 1

What are the 4 principles of toxicology?

Answer 1

1) Resuscitation (ABCs)
2) Screening (toxidrome? clinical clues?)
3) Decrease absorption of drug
4) Increase elimination of drug

Question 2

History features to elicit in toxicology work up?

Answer 2

• Age / weight / PMHx/ Rx
• Substance and quantity
• Time since exposure (determines prognosis and need for decontamination)
• Symptoms since
• Route
• Intention ?suicidality

Question 3

Exam features of toxicology work up?

Answer 3

• ABCs
• LOC/GCS
• Vitals
• Pupils

Question 4

General approach to toxicology? (ABCs of toxicology)

Answer 4

• A/B/C as per usual
• D1: Drugs (universal antidotes, as need to resuscitate pt)
• D2: draw bloods
• D3: Decontamination (decrease absorption
• Examine (specific toxidrome)
• Full vitals, ECG, Foley, Xrays
• Give specific antidotes /Rx

Question 5

What are the universal antidotes?

Answer 5

DONT

• Dextrose
• Oxygen
• Naloxone
• Thiamine (give BEFORE dextrose)

Question 6

When should dextrose be given as universal antidote?

Answer 6

To any pt presenting w/ altered LOC.

Question 7

What is the exception to oxygen as a universal antidote?

Answer 7

Usually give O2 to any pt ?tox (even COPD CO2 retainer).

EXCEPT paraquat / diquat (herbicides) ==> O2 radicals increase morbidity.

Question 8

What is naloxone?

Answer 8

Central u-receptor competitive antagonist.

Opioid antidote: both therapeutic and diagnostic with onset

Question 9

Which populations are at risk for thiamine deficiency?

Answer 9

• Alcoholics
• Anorexics
• Hyperemesis of pregnancy
• Malnutrition states

Question 10

What is thiamine?

Answer 10

necessary cofactor for glucose metabolism. Give before dextrose / glucose!!

Question 11

Toxicology screen bloods?

Answer 11

-FBE
-UEC
-BSL
-INR/APTT
-LFTs
-Osmolality
-ABGs
-ASA
-Paracetamol
-EtOH levels
-CMP
Other as per clinical picture

Question 12

Gastrointestinal decontamination?

Answer 12

• SDAC: adsorption of drug/toxin to AC prevents availability

- Whole bowel irrigation (polyethylene glycol)

Question 13

CIx SDAC?

Answer 13

• Caustics
• SBO
• Perforation
• Risk of aspiration

Question 14

Which drugs respond to urine alkalisation?

Answer 14

• Aspirin / ASA
• Methotrexate
• Phenobarbital
• Chlorpropramide

Question 15

Rationale for urine alkalinisation in toxicology?

Answer 15

Weakly acidic substances can be trapped in alkali urine (pH >7.5) to increase elimination.

Question 16

Treatment paracetamol overdose?

Answer 16

• Decontaminate (SDAC)

- N-acetylcysteine

Question 17

What is the toxic dose of paracetamol?

Answer 17

> 200mg/kg (adult >7.5g)

Question 18

Monitoring in paracetamol overdose?

Answer 18

• LFTs
• Coags
• UEC

Question 19

Signs of poor prognosis in paracetamol overdose?

Answer 19

• Hypoglycemia
• metabolic acidosis
• Encephalopathy

Question 20

Timeline of paracetamol toxicity?

Answer 20

• STAGE1 (0-24h): asymptomatic / GI upset
• STAGE2 (24-48h): RUQ pain and tenderness, progressive elevation of LFTs, bilirubin, pt
• STAGE3(48-96h): hepatic failure
• STAGE4: death from hepatic failure / normalisation of LFTs and complete resolution of hepatic architecture by 3/12

Question 21

What are the toxidrome?

Answer 21

• Anticholinergic
• Cholinergic
• Sympathomimetic
• Opiate
• Sedative hypnotic

Question 22

Mx and Rx snake toxicity?

Answer 22

-Neurotoxic
-Myotoxic
-Coagulopathic
Rx = antivenoms

Question 23

Mx and Rx blue ringed octopus toxicity?

Answer 23

-Tetrodotoxin - muscle paralysis

Rx: respiratory support; no antidote

Question 24

Mx and Rx box jellyfish toxicity?

Answer 24

-Multicomponent venom: cardiotoxic

Rx: vinegar as 1st aid; antivenom

Question 25

Mx and Rx stonefish toxicity?

Answer 25

-Neurotoxic, myotoxic, cardiotoxic

Rx: antivenom

Question 26

Mx and Rx funnel web spider toxicity?

Answer 26

Stimulation of nerves

Rx: antivenom