Common intoxications Flashcards
Induction of emesis
may remove up to 40-80% of the ingested materia
most effective within 1 hour of ingestion, limited benefit more than 4 hours after ingestion
Requires presence of food in the stomach
CONTRAINDICATED FOR CORROSIVE/CAUSTIC TOXINS AND FOR PETROLEUM DISTILLATES OR IN PATIENTS WITH DEPRESSED MENTAL STATUS OR SEIZURES
Options for inducing emesis
Apomorphine (poorly effective in cats)
Xylazine (useful in cats, effective in only 40-75% of cases)
Dexmedetomidine (sedation and resp depression can occur)
Syrup of ipecac and hydrogen peroxide (uncommonly used, irritant effects on gastric mucosa)
Gastric lavage
Useful for patients where emesis is ineffective or contraindicated, although requires the patient to be unconscious or anesthetised
CONTRAINDICATED IN FOR CORROSIVE/CAUSTIC TOXINS AND FOR PETROLEUM DISTILLATES and may be ineffective for congealed or “chunky” material.
Potential complications for gastric lavage
aspiration, increased transit of the toxin into the small intestine, or potentially electrolyte disturbances or oesophageal trauma.
Activated charcoal administration
Acts by adsorption
Most beneficial when given <2h after toxin ingestion, may still be useful up to 24h,
should not be given to patients at risk for aspiration pneumonia or if GI perforation suspected
Cathartics
Less commonly used
Enhance elimination of substances - promotes movement through GI tract
Contraindicated if patient is dehydrated or has diarrhoea, ileus, or intestinal obstruction
Types of cathartics
Bulk cathartics (metamucil, pumpkin)
Osmotic cathartics (sorbitol)
Lubricant cathartics (mineral oil - reduced efficacy of activated charcoal)
Intralipid infusion
treatment of lipophilic toxins
20% fat emulsion for IV infusion
oil in water emulsion, including long-chain and medium chain triglycerides and egg phospholipids
Essentially acts as a “lipid sink” for lipophilic toxins
expected to cause hyperlipidaemia and may cause other adverse effects e.g. pancreatitis and “fat overload syndrome”
Toxin in chocolate
Methylxanthines - particularly theobromine and caffeine
Mechanism of chocolate toxicity
Inhibit cellular phosphodiesterase
- increase in cyclic AMP
- release of catecholamines
Clinical signs of chocolate toxicity
20 mg/kg -> clinical signs,
40-50 mg/kg -> severe signs,
60 mg/kg can cause seizures
CNS/muscle stimulation (hyperactivity, restlessness, incoordination, seizures, tachycardia, and arrhythmias),
diuresis,
vomiting and diarrhoea,
excessive urination,
arrhythmias,
hyperthermia,
incoordination.
Timeframe for chocolate toxicity
clinical signs begin within 12h of ingestion and can last up to several days with large ingestions (long half-life)
Treatment of chocloate toxicity
Emesis/gastric lavage if recent + activated charcoal (activated charcoal every 3 to 8 hours for up to 72 hours)
Diazepam/phenobarbital may be needed to control seizures and management of arrhythmia may be necessary (lidocaine, propanolol)
Toxin in anticoagulant rodenticides
First-generation (e.g., warfarin, pindone),
or
more potent, longer-lasting second-generation (e.g., brodifacoum, bromadiolone, diphacinone, chlorophacinone).
Mechanism in anticoagulant rodenticide toxicity
Competitively inhibits vitamin K epoxide reductase which is essential for the formation of coagulation factors II, VII, IX, and X.
Clinical signs in anticoagulant rodenticide toxicity
Clinical signs relate to haemorrhage, esp exercise intolerance, lethargy, haemoptysis, intracavitary bleeding.
Mucosal bleeding, petechiation/ecchymosis etc may occur but less common than disorders of primary haemostasis (e.g. immune-mediated thrombocytopaenia)
TImeframe of anticoagulant rodenticide toxicity
Whilst absorption is rapid, prolongation of PT/APTT is not observed or measurable for 36-48 hours due to the half-life of factor VII. Clinical signs typically do not develop for 3-5 days.
Treatment of anticoagulant rodenticide toxicity
If recent ingestion, reasonable to induce emesis and assess PT/APTT at 36-48h.
If prolonged at that time, vitamin K1 should be administered for 7 (first generation) to 30 (second generation) days and PT/APTT should be reassessed after stopping treatment.
For patients with clinical evidence of haemorrhage, Vit K1 +/- plasma or blood transfusion, and intensive care may be required.
Mechanism of NSAID toxicity
Inhibits the activity of cyclooxygenase (COX, mainly COX-1 and -2), reducing conversion of arachidonic acid to prostaglandins, prostacyclins and thromboxane.
COX-1 appears generally has more role in autoregulation/homeostasis whereas COX-2 is more important in the production of inflammatory mediators but COX selectivity is often lost following overdose.
Clinical signs of NSAID toxicity
Gastric ulceration (vomiting, haematemesis, melena, abdominal pain) and/or acute kidney injury (PUPD/oliguria/anuria, anorexia, lethargy, and vomiting).