Decontamination and enhanced elimnation Flashcards
Which drugs can be dialysed (IHD or CRRT)?
Metals
- Lithium (rebound effect), potassium
Antiepileptics
- Carbamezepine, Valproate
Toxic alcohols
- Ethanol, methanol, ethylene glycol
Miscellaneous
- Salicylates
- Methotrexate (rebound effect)
- Metformin
- Theophylline
- Paraquat
What are the different types of decontamination?
- Single Dose Charcoal
- Multi dose (MDAC)
- Whole bowel irrigation
- External decontamination ie a shower
What are the different types of enhanced elimination?
MDAC (Decontamination + enhanced elimination)
Urinary alkalinisation
Extracorporeal elimination
- RRT
- Haemoperfusion
- Charcoal haemoperfusiojn
Exchange transfusion
- form of extracoporeal but very specific ie methhaemglobinaemia
What are the indications and contraindications to MDAC?
Indications
- Amitryptiline
- Carbamezapine
- Digoxin
- dapsone
- quinine
- theophylline
- phenytoin
- phenobarbitone
- colchicine
- Sotalol
- Amatoxin (Amanita Phalloides)
Contraindications
- Airway not protected
- bowel obstruction
- Unco-operative patient
Useless overdoses
- Too rapid (ethanol, paraquat)
- Metals (iron, lithium etc)
- Corrosive substances
Works by interrupting entero-hepatic recirculation
What are the indications and contraindications to urinary alkalinisation?
Indications- Phenobarbitone and salicylates
Contraindications- Fluid overload
Alkaline urine promotes the ionisation of highly acidic drugs
Complications- Alkalaemia, hypokalaemia, hypocalcaemia
How is urinary alkalisation performed?
1-2mmol/kg bolus of sodibic
then infusion 37.5mmol/hr
Dipstick urine aiming pH >7.5
What is the indication for exchange transfusion in toxicology?
Refractory Methaemglobinaemia
When is CRRT better than IHD?
- Haemodynamically unstable (less rapid fluid shifts)
- Substance prone to rebound phenomenon (lithium, methotrexate)
- Very long plasma half life
- Large volume of distribution and highly protein/tissue bound
What are the indications for dialysis with valproate overdose?
- Serum VPA level >6000umol/L
- Severe toxicity (pH <7.1, cerebral oedema, CVS collapse)
- Empiric if ingestion >1000mg/kg
End point- clinical improvement and serum conc <700umol/L
How is whole bowel irrigation (WBI) performed?
Large amounts of Poly-ethylene glycol based isoosmotic agents
- Movicol, glycoprep etc
Usually via an NGT even in awake patients
- May benefit from 10-20mg Maxalon
Adults 1-2L/hr, kids 25mls/kg/hr
End point is when rectal effluent is clear +/- absence of toxin on xrays (ie iron tablets)
What are the indications for WBI?
Metals
- Iron, lithium, potassium, lead
SR preparations
- CC blockers (ie verapamil_
- Venlafaxine
- Body packers/stuffers
Needs to be started within 4hrs of ingestion
What are the indications for Haemoperfusion (charcoal, resins, drug specific antibodies)?
Some charcoal susceptible drugs for charcoal haemoperfusion
- Carbamezepine
- theophylline
- amanita phylloides
- Digoxin
- Paracetamol
- Diltiazem
Others
- Metoprolol, Colchicine, Promethazine
Complications
- Hypoelectrolytes
- Depletion of coagulation factors, DIC, thrombocytopaenia
- Depletion of WCC + immune mediators
- Haemolysis
- Charcoal embolization
What is the main indication for Plasmapharesis in toxicology?
Amanita phylloides
- Reduces mortality from 20% to 5%
What special precuations and decontamination is required for Organophosphate poisoning?
- Standard bodily fluid contact precautions
- ideally well ventilated room
- No risk of nosocomial toxicity, however the solvents fumes may cause headache and nausea (making people panic)
Remove patients clothes and wash their body with soap/water. NG can be placed to both aspirate imbibed organophosphates and give charcoal
What are the indications for activated charcoal with paracetamol overdose?
- Acute IR ingestion >10gm or 200mg/kg <2hrs post ingestion
OR - Massive acute IR ingestion >30gm or >500mg/kg <4hrs post ingestion
OR - Acute SR ingestion >10gm or 200mg/kg <4hrs post ingestion
