Toxicology Flashcards
What are the 4 principles of toxicology?
1) Resuscitation (ABCs)
2) Screening (toxidrome? clinical clues?)
3) Decrease absorption of drug
4) Increase elimination of drug
History features to elicit in toxicology work up?
- Age / weight / PMHx/ Rx
- Substance and quantity
- Time since exposure (determines prognosis and need for decontamination)
- Symptoms since
- Route
- Intention ?suicidality
Exam features of toxicology work up?
- ABCs
- LOC/GCS
- Vitals
- Pupils
General approach to toxicology? (ABCs of toxicology)
- 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
What are the universal antidotes?
DONT
- Dextrose
- Oxygen
- Naloxone
- Thiamine (give BEFORE dextrose)
When should dextrose be given as universal antidote?
To any pt presenting w/ altered LOC.
What is the exception to oxygen as a universal antidote?
Usually give O2 to any pt ?tox (even COPD CO2 retainer).
EXCEPT paraquat / diquat (herbicides) ==> O2 radicals increase morbidity.
What is naloxone?
Central u-receptor competitive antagonist.
Opioid antidote: both therapeutic and diagnostic with onset
Which populations are at risk for thiamine deficiency?
- Alcoholics
- Anorexics
- Hyperemesis of pregnancy
- Malnutrition states
What is thiamine?
necessary cofactor for glucose metabolism. Give before dextrose / glucose!!
Toxicology screen bloods?
-FBE
-UEC
-BSL
-INR/APTT
-LFTs
-Osmolality
-ABGs
-ASA
-Paracetamol
-EtOH levels
-CMP
Other as per clinical picture
Gastrointestinal decontamination?
- SDAC: adsorption of drug/toxin to AC prevents availability
- Whole bowel irrigation (polyethylene glycol)
CIx SDAC?
- Caustics
- SBO
- Perforation
- Risk of aspiration
Which drugs respond to urine alkalisation?
- Aspirin / ASA
- Methotrexate
- Phenobarbital
- Chlorpropramide
Rationale for urine alkalinisation in toxicology?
Weakly acidic substances can be trapped in alkali urine (pH >7.5) to increase elimination.
Treatment paracetamol overdose?
- Decontaminate (SDAC)
- N-acetylcysteine
What is the toxic dose of paracetamol?
> 200mg/kg (adult >7.5g)
Monitoring in paracetamol overdose?
- LFTs
- Coags
- UEC
Signs of poor prognosis in paracetamol overdose?
- Hypoglycemia
- metabolic acidosis
- Encephalopathy
Timeline of paracetamol toxicity?
- 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
What are the toxidrome?
- Anticholinergic
- Cholinergic
- Sympathomimetic
- Opiate
- Sedative hypnotic
Mx and Rx snake toxicity?
-Neurotoxic
-Myotoxic
-Coagulopathic
Rx = antivenoms
Mx and Rx blue ringed octopus toxicity?
-Tetrodotoxin - muscle paralysis
Rx: respiratory support; no antidote
Mx and Rx box jellyfish toxicity?
-Multicomponent venom: cardiotoxic
Rx: vinegar as 1st aid; antivenom
