Q: Simply the notes A: Treatment of Poisoning: Simplified Notes Forensic Medicine & Toxicology, pp. 446-449 Overall plan 1. Resuscitate: airway intubate if needed, oxygen, circulation IV fluids and drugs, and correct CNS depression. 2. Remove the poison: gastric lavage, emetics, or removal of clothing and washing the body for skin poisons. 3. Give antidotes. 4. Enhance excretion: forced alkaline diuresis, dialysis, hemoperfusion. 5. Give symptomatic care: maintain electrolytes, pulse, BP and breathing. --- 1. Gastric lavage stomach wash - Timing: most useful within 3 hours of ingestion. Earlier is better. - Tube: Ewald's or Boa's tube. - Red rubber, 1.5 m long, 1 cm diameter. - Funnel at the upper end. - Blunt, round lower end with 1 or 2 side holes. - Suction bulb at the midpoint. - Mark at 50 cm from the lower end. Procedure - Position: left lateral decubitus, head lower than the larynx Tendelenburg. - Use a mouth gag with a central hole to stop the patient biting the tube. - Pass the tube to the 50 cm mark. Do not use force, and make sure it does not enter the trachea. - Pour about 250 ml of warm water through the funnel. - When the funnel is empty, lower it and press the bulb to drain the stomach. - Keep the first wash for chemical analysis. - An antidote can be added to the wash water. Contraindications and special cases Situation What to do ------ Convulsions Wash only after the convulsions are controlled Corrosive acids and alkalies not phenol Acid: no lavage, but carefully aspirate with a soft rubber tube to prevent perforation. Concentrated alkali: no tube at all risk of oesophageal perforation Unconscious patient Wash only after endotracheal intubation Children Use a Ryle's tube or a 22-28 F orogastric tube to aspirate Volatile poisons kerosene, petrol Contraindicated aspiration pneumonia. Intubation protects the lungs Oesophageal varices, hypothermia Contraindicated 2. Emetics - No longer recommended. Use only if lavage is not available. - Avoid in unconscious patients because of aspiration risk. - Ipecacuanha syrup is the safe emetic. - Mustard powder and common salt are not recommended. - Apomorphine cannot be used orally. - Tickling the fauces is not advisable. - For skin-absorbed poisons, remove clothing and wash the body. --- 3. Antidotes 4 types A. Mechanical physical Activated charcoal - Fine black odourless powder from distillation of organic material. - Action: adsorbs the poison in its pores. - Dose: 60-100 g in adults, 15-30 g in children. - Useful in: - Barbiturates - Benzodiazepines - Opiates - Nicotine - Strychnine - Phenothiazines - Digitalis - Anti-epileptics - Salicylic acid - Alcohol - Phenol - Not useful in: corrosives, heavy metals, cyanide, hydrocarbons. - Side effects: nausea, vomiting, diarrhoea, constipation. Demulcents - Form a protective coating on the gastric mucosa. - Examples: milk, starch, egg white, milk of magnesia. B. Chemical They react with the poison to form harmless precipitates. - Albumin precipitates mercuric chloride. - Copper sulphate precipitates phosphorus. - KMnO₄ is an oxidiser. It is used in the wash for opium, strychnine, phosphorus and atropine. - Tannic acid is used in strychnine, nicotine, cocaine, aconite, lead, silver, aluminium, cobalt, copper, mercury and zinc poisoning. - The "universal antidote" charcoal 2 parts, magnesium sulphate 1 part, tannic acid 1 part is no longer used. Tannic acid reduces charcoal's adsorption. C. Physiological pharmacological These have effects opposite to the poison. - Atropine for organophosphorus poisoning. - Diazepam for strychnine poisoning. D. Specific antidotes These inactivate the poison directly or block its receptor. - Chelating agents for metals. - Oximes for organophosphates. --- 4. Chelating agents Chelators bind metals more strongly than the body's enzymes do. They form a water-soluble ring complex that is excreted in urine. Agent Used for Dose and route Key points ------------ BAL dimercaprol Arsenic, mercury, lead, bismuth, copper, gold 3-4 mg/kg. 50 mg IM every 4 h for 2 days, then twice daily for 10 days Has 2 SH groups. Give within 4 h. IM only, never IV oil base, risk of fat embolism. Comes as 100 mg/ml, 2 ml ampoule EDTA calcium disodium versenate Lead, mercury, cobalt, manganese, cadmium 25-35 mg/kg. 1 g in 250-500 ml of 5% glucose or saline IV drip, twice daily for 5 days Better than BAL for lead Penicillamine Copper, zinc, lead, mercury 30 mg/kg orally, up to 2 g/day in 4 divided doses for 7 days Stable SH group. Side effects: hypersensitivity, pyridoxine deficiency, thrombocytopenia, drug fever, nephrotic syndrome Desferrioxamine Iron 8-12 g/day orally in divided doses. Can also be given IM or IV Water soluble Succimer DMSA Lead 10 mg/kg orally every 8 h for 10 days Oral. Less toxic and better than EDTA for lead. Safe in G6PD deficiency BAL side effects: anorexia, nausea, vomiting, restlessness, salivation, lacrimation, body ache, raised temperature, fall in BP, chest tightness, burning eyes. BAL contraindications: - Pre-existing liver damage - Severe kidney damage - Cadmium or iron poisoning nephrotoxic combinations EDTA side effects: anorexia, nausea, vomiting, hypersensitivity, fall in BP, vertigo. EDTA contraindications: raised intracranial tension, renal damage. --- 5. Enhancing elimination Forced alkaline diuresis - Raises urine pH to 7.5-9. - Used for salicylates, barbiturates, chlorpropamide and methotrexate. - Give 50-100 mEq sodium bicarbonate in 1 L of 0.45% saline at 250-500 ml/h IV. Diaphoretics alcohol, ipecac, pilocarpine, salicylates: usefulness is doubtful. Peritoneal dialysis - Removes alcohols, long-acting barbiturates, chloral hydrate, lithium, salicylates, bromide, inorganic mercury, quinidine, theophylline and sodium chlorate. - Exchange volume is 2 L in adults and 200 ml in children under 5. - It is only 10-25% as effective as hemodialysis. - Exchange transfusion is useful for barbiturates, CO and salicylates, especially in children. Hemodialysis: useful in - Methanol - Ethanol - Ethylene glycol - Chloral hydrate - Lithium - Acetaminophen - Bromides - Phenobarbital - Salicylates - Fluorides - Sodium chlorate - Methaqualone - Boric acid - Thiocyanates - Oxalic acid - Heavy metals possibly Hemodialysis: NOT useful in - Organophosphates - Kerosene oil - Digitalis - Copper sulphate - Benzodiazepines - Amphetamine Hemoperfusion blood passes through a charcoal or resin filter, for severe poisoning with: - Barbiturates - Meprobamate - Methaqualone - Paraquat - Salicylates - Mushrooms amatoxin - Carbon tetrachloride --- 6. Coma cocktail Given IV to a comatose patient when the poison is unknown. 1. Dextrose 50%, 100 ml. 2. Thiamine Vit B1, 100 mg. 3. Naloxone, 2 mg. - It covers hypoglycaemia, alcohol thiamine and opiate poisoning. - It is harmless even if the patient has not taken these. - In children, omit thiamine and reduce dextrose to 25%. --- Quick exam hooks - Lavage within 3 h, tube to 50 cm, 250 ml warm water, left lateral. - No lavage in corrosives, volatile poisons kerosene, petrol, varices or hypothermia. Intubate first if the patient is unconscious. - Charcoal does not bind corrosives, heavy metals, cyanide or hydrocarbons. - BAL: IM only. Desferrioxamine: iron. Succimer: lead. Penicillamine: copper. Penicillamine is also marked with an asterisk for mercury in the text. - Coma cocktail: Dextrose, Thiamine, Naloxone. Caveats: - I could not read the faint text in the page margins. - The book's emetic and universal antidote sections are old-style teaching. Current practice has largely dropped ipecac. - Gastric lavage and forced alkaline diuresis are now used selectively. Urinary alkalinisation is mainly kept for salicylate poisoning. - I did not run a PubMed check for newer evidence on these points.
