Acute poisoning

Acute poisoning Common medical emergency Its incidence varies in different countries Substances involved in poisoning vary as well Paracetamol poisoning is very common in UK (48% of all cases of poisoning), while it is rare in Iraq. Organophosphorus poisoning on the other hand is very common in developing countries including Iraq.

Assessment of an acutely poisoned patient First aid measure History taking Standard clinical examination Laboratory investigation

First aid measure First aid measure should ensure that: Airway is clear Breathing is adequate Circulation is not compromised

History taking History taking should include: Establishing the diagnosis of poisoning Calculating the duration since exposure to the toxic substance Identification of the drug or substance abused Asking about the cause of poisoning Considering the symptoms since poisoning Asking about past medical and psychiatric history

Clinical examination Start standard clinical examination esp. considering:  State of consciousness (better assessed by Glasgow coma scale) Most cases of poisoning can lead to disturbance of consciousness, but this is especially true in case of psychotropic drugs. In an unconscious patient, carefully exclude stroke, hypoglycemia, diabetic ketoacidosis, CNS infection (meningitis and encephalitis), uraemia, hepatic encephalopathy, and brain injury.

Clinical examination Pupil size: Small (miosis): Opioids (narcotics) OP (organophosphorus) Large (midriasis): Anticholenergics TCAD Alcohol Antihistaminics

Clinical examination Respiratory rate: Reduced: Opioids Benzodiazapines Increased Salicylates

Clinical examination Blood pressure: Hypotension TCAD Salicylates Phenthiazines Hypertension  agonists

Clinical examination Heart rate: Tachycardia (or tachyarrhythmia): TCAD, Digoxine Theophylline Anticholenergics Antihistamines Bradycardia (or bradyarrhythmia): Digoxine CCB (calcium channel blockers)  Blockers Opioids

Clinical examination Temperature: Fever: Anticholenergic Salicylates SSRI Hypothermia: CNS depressants Phenthiazines

Clinical examination Cerebellar signs (esp. nystgmus): Anticonvulsants Alcohol Extrapyramidal signs: Phenthiazines Metoclopromide Convulsions: TCAD Theophylline Anticonvulsants NSAIDs

Clinical examination Sweating: Salicylates OP Cyanosis: CNS depressants Methaemoglobinaemia Jaundice: Paracetamol Needle tracts: Drug abuse

Toxicology study Urea, creatinine and electrolytes should be measured in most patients. Arterial blood gases and acid base balance should be checked in those with significant respiratory or circulatory symptoms and when the poison is likely to affect acid base balance Toxicology laboratory is needed for The measurement of serum level of paracetamol (and to a lesser extent of aspirin) to plan subsequent management. Other types of poisoning are diagnosed by urine or gas chromatography (only in difficult cases and for medico-legal indications).

General management of acute poisoning A. Prevention of further absorption B. Supportive care C. Antidotes D. Psychiatric consultation

A. Prevention of further absorption Removal of clothing and skin washing with soap and water in case of contamination by chemicals or pesticides. Eye irrigation by normal saline for 15 min. in case the eye is contaminated. Patients breathless or wheezy because of inhaling toxic gases or fumes should receive oxygen and bronchodilator nebulization

A. Prevention of further absorption Ingested poisons are removed by: Gastric lavage Activated char coal Whole bowel irrigation Urinary alkalization Haemodialysis and haemoperfusion

A. Prevention of further absorption Gastric lavage: Only if potentially life threatening amounts are ingested (not to be used for acids, alkalis, or petroleum distillates poisoning). No gastric lavage should be attempted in unconscious patient unless the airways are protected by cuffed endotracheal tube.

A. Prevention of further absorption Activated charcoal: it adsorbs most toxins and is the method of choice to prevent further drug absorption. For patients poisoned within one hour, 50 gm is given orally. The dose can be repeated every 4 hours for carbamazepine, theophylline poisoning. For patients with disturbed consciousness or those who can not swallow, activated charcoal is administered through nasogastric tube and the airway should be protected to avoid aspiration pneumonitis. If multiple doses are needed, a laxative (like sorbitol) is given to avoid intestinal obstruction. Certain poisons are not adsorbed by charcoal, including iron, lithium, acids, alkalis, ethanol, methanol and petroleum distillates

A. Prevention of further absorption Whole bowel irrigation: Polyethylene glycol is administered orally for potentially toxic ingestion of iron, lithium, and theophylline. One litre is ingested every hour until the rectal effluent is clear. Contraindications include GI bleeding or ulceration Urinary alkalinization: Indicated for severe salicylate poisoning Haemodialysis or haemoperfusion: Effective methods of treating severe poisoning by salicylate, theophylline, carbamazepine, and methanol

B. supportive care 1. Unconscious patients are better treated in intensive care units with general treatment of comatose patient provided. Regular recording of Glasgow coma scale is important. 2. Convulsions are treated with IV diazepam 10mg IV repeated as necessary. 3. If cardiac complications are present or expected, the patient is put under continuous ECG monitoring. 4. Ventilatory support may be needed for those with respiratory depression.

C. Antidotes Antidote Poison Vitamin K, fresh frozen plasma Anticoagulants (warfarine, rodenticides) IV glucagon, adrenaline  blockers Calcium gluconate (or chloride) Calcium channel blockers Cobalt edetate, Sodium thiosulphate, Nitrites, Hydroxycobalamine Cyanide Ethanol, 4 methylpyrazol Methanol, Ethylene glycol Naloxone Opioids (narcotic analgesics) Atropine, Oximes OP (organophosphorus compounds) N. acetylcysteine, Methionine Paracetamol Digoxine specific Ab fragments Digoxine Desferrioxamine Iron salts

D. psychiatric consultation : This is essential for patients who have attempted suicide. The psychiatrist should be consulted as soon as the patient recovers.

Substances of low toxicity Certain substances are of very low toxicity even if ingested in high doses. Examples include: most antibiotics (except antiTB, and tetracyclines) antiulcer drugs (H2 blockers and PPIs) oral contraceptive pills chalk paper glue washing liquids