- As with medicine the risk attempts to reduce absorption need to be considered in light of the potential toxicity of the ingested substance. In some cases, gastric lavage is attempted and in others not.
- Now used much less than before. Airway protection against aspiration is fundamental to avoid aspiration. Only done if serious and difficult to manage overdose taken within last hour.
- Ideally patient intubated with an anaesthetist at hand. Ensure oxygen and suction at hand. place patient in left lateral head-down position. Raise the foot of the bed.
- Avoid if corrosive agents or petroleum products taken which can cause chemical pneumonitis and ARDS if aspirated. A lubricated size 36-40 FG stomach tube inserted and attached to a funnel. Listed over the stomach for injected air or aspirate gastric juices.
- If intubated then concerns about being in the trachea are unwarranted. Poor in 300 ml aliquots and then allow aspirate to come out. Massage over the stomach to help tablets out. Finish with 50 g of activated charcoal. Questionable effectiveness.
- Ipecac was once used to induce vomiting in poisoned patients for whom there was a chance to get the toxin out of the body. Now rarely used. Many believe that ipecac and gastric lavage are essentially worthless, potentially harmful, and unlikely to alter morbidity and mortality in the real world.
- High degree of microporosity. 1 gram of activated carbon has a surface area in excess of 500 m2. May be considered when less than 1 hour since tablets taken.
- Activated carbon binds materials by van der Waals force or London dispersion force. Does not bind alcohols, glycols, strong acids and bases, metals and most inorganics, such as lithium, sodium, iron, lead, arsenic, fluorine, and boric acid very well or hydrocarbons.
- Activated charcoal is estimated to reduce the absorption of some substances by up to 60%. It remains within the GI tract and eliminates the toxin in faeces. Large amounts require laxative to ensure passage.
- Best taken by the cooperative patient or if not then consider administration via nasogastric tube. For drug overdose or poisoning: 50 to 100 grams of activated charcoal is given at first. Unless a patient has an intact or protected airway, the administration of charcoal is contraindicated.
Multi-dose activated charcoal
- For drug overdose or poisoning: 50 to 100 grams of activated charcoal is given at first, followed by charcoal every 2 to 4 hours at a dose equal to 12.5 grams per hour. For children, lower doses (10 to 25 grams) are used.
- Used to interrupt enteroenteric, enterogastric, and enterohepatic circulation of absorbed drugs. Used for carbamazepine, dapsone, phenobarbital, quinine, or Theophylline toxicity. Unless a patient has an intact or protected airway, the administration of charcoal is contraindicated.
Total bowel irrigation
- Polyethylene glycol is given via NG into bowel. About 2L/hour given. Useful for body packers, sustained release formulations. This does not cause fluid shifts. Administer until clear effluent from bowels.
- Useful for substances not heavily protein-bound.
- Alcohol, Dabigatran, Salicylates, Lithium and ethylene glycol
- Valproate, methanol and Theophylline, carbamazepine
Some overdose Issues:
- Hyperthermia: Iced baths, Dantrolene.
- Ongoing seizures IV Diazepam 5-10 mg.
- Acute anxiety: IV Diazepam 2-10 mg IV
- Bradycardia: IV Atropine, Isoprenaline, Ventricular pacing, Calcium/HyperInsulin normoglycaemic therapy for Calcium channel blockers, Glucagon. Digibind for Digoxin OD.
- Nausea/Vomiting: Metoclopramide, Ondansentron.