Poisoning Flashcards
Poison
Substance that causes disturbances to an organism when a sufficient amount is absorbed.
Toxin
Poison produced biologically
Venom
toxin injected by bite or sting
Toxicity
inherent capacity of a chemical, including drugs, to cause injury.
Nonselective actions
Local irritation
Site of exposure
Injury=denaturing macromolecules
Strong acids and alkali
Selective actions
Interferes with specific biochemical pathways
Chemical has to be absorbed and distributed to a specific pathway
Describe Organophosphate poisoning
Immediate action
Acetylcholinesterase inhibition can cause immediate symptoms
Paracetomol overdose
Selective action
depletion of glutathione needed for conjugating the toxic metabolite NAPQI
Rattex poisoning
Selective action
(rodenticide/”superwarfarins”) contains warfarin and interferes with the Vitamin K pathway
TCA overdose
coma
Describe and provide examples of TCAs.
Block the re-uptake of serotonin and noradrenaline from the synapse.
Amitryptiline, Imipramine and Clomipramine
Sign of Opiate overdose
Respiratory Depression
Hypoventilation.
Antidote for opiate overdose.
Naloxone- Attaches to opioid receptor and blocks/displaces it
Pharmocological antagonist
Criteria for emesis.
time since ingestion <1hr
children
charcoal not indicated.
Methods for emesis.
stimulation of pharynx
Ipecacuanha: Rarely used (lack of evidence)- considered in alert and conscious, early presentation.
Multiple drugs.
Contraindications to emesis.
Impaired level of consciousness
Corrosive substances
Hydrocarbons
Risk of seizures
Criteria for gastric lavage.
time since ingestion < 1-2 h
Large amount of toxic solid substance
Need to remove whole tablets.
Especially considered in patients who have ingested a toxin for which there isn’t an effective treatment once absorbed.
Explain the process of Gastric lavage.
Use LARGE-bore catheter (32-40)
200 – 300ml tap water in adults
10ml/kg body temperature saline in kids
Position head down and left lateral position. (Airway protection)
small amounts of water–> this minimise risk of gastric contents entering duodenum.
Contraindications for gastric lavage.
Corrosive substances and hydrocarbons
Risk of GI haemorrhage
Unprotected airway
Indications for Activated Charcoal.
Salicylates, paracetamol, barbiturates, digoxin, TCAs
Time since ingestion < 2 h
Longer if delayed gastric emptying
When would you consider a MDAC?
Severely poisoned patients
Sustained-release tablets
Enterohepatic cycling (estrogen, TCAs)
Drugs secreted into bile or intestine (digoxin)
Contraindications for activated charcoal.
Strong acids or alkalis
Iron salts
Lithium
Petroleum products
Cyanide
Endoscopy due
Antidote by mouth
Adverse effects of activated charcoal.
Vomiting
Constipation/diarrhea
Intestinal obstruction
Describe whole bowel irrigation.
PEG electrolyte solution orally (large volume)
Stimulates peristalsis
Useful in lethal doses iron, Body Packers
