Toxicology Definitions and Treatment Principles
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Toxicology Definitions and Treatment Principles
- 2. Definitions ā¢ Poison: ā¢ Any substance that can cause severe organ damage or death if ingested, breathed in, or absorbed through the skin ā¢ Toxin: ā¢ A poisonous substance, especially a protein, that is produced by living cells or organisms and is capable of causing disease when introduced into the body tissues but is often also capable of inducing neutralizing antibodies or antitoxin.
- 3. Definitions ā¢ Toxicity: ā¢ Degree to which a substance can damage an organism ā¢ Toxicology: ā¢ The study of the nature, effects, and detection of poisons (toxins) and the treatment of poisoning.
- 4. Treatment of Poisoning: Principles Resuscitation Risk Assessment Supportive Care and Monitoring InvestigationsDecontamination Enhanced Elimination Antidotes Disposition
- 5. Resuscitation: The ABCDE way! Check for Goal Possibility Possible Measures Airway Maintain patency Patent Obstructed Position: Left lateral, Head down Suctioning Intubation +/- Guedelās Airway
- 6. Resuscitation: The ABCDE way! Check for Goal Possibility Possible Measures Breathing Maintain adequate oxygenation and ventilation Spontaneous Apnoeic SpO2 levels Start Oxygen at 2L/min via face mask Intubation +/- Guedelās Airway Check for falling SpO2
- 7. Resuscitation: The ABCDE way! Check for Goal Possibility Possible Measures Circulation Maintain perfusion to vital organs Feel for Pulses BP recordable(?) Attach Monitor, look for rhythm consider inotropes (dobutamine) Start Crystalloids (Normal Saline preferred) +/- Consider vasopressors (adrenaline)
- 8. Resuscitation: The ABCDE way! Check for Goal Possiblity Possible Measures Disability Assess level of Consciousness; Correct life threatening conditions Institute Resuscitative Antidotes Glasgow Coma Scale or AVPU scale Hypoglycaemia; Hypethermia; Seizure(focal/generalis ed) Antidotes Dextrose bolus injection; active cooling; benzodiazepam (diazepam)
- 9. Resuscitation: The ABCDE way! Check for Goal Possiblity Possible Measures Exposure Assess Toxidromes Cholinergic/Anticholinergic Delirium, Agitation, Neuroleptic Malignant Syndrome Manage Accordingly
- 10. Risk Assessment ā¢ Distinct Quantitative Cognitive Step ā¢ Ascertain: ā¢ Agent(s) ā¢ Dose(s) ā¢ Time since ingestion ā¢ Clinical features and progress ā¢ Patient factors and co-morbidities Methods: ā¢ History by patient himself/herself; attendants ā¢ Missing medicines at home, previous medical records, agents available at home
- 11. Supportive Care and Monitoring ā¢ Fate: ā¢ Emergency Observation Unit ā¢ Intensive Care Unit ā¢ Initially should be done in ED ā¢ Duration of Monitoring determined by: ā¢ Agent(s) ingested ā¢ Formulation involved ā¢ Disposition from ED depends on: ā¢ Current clinical status ā¢ Expected clinical status
- 13. Investigations in Poisoning or Overdoses Screening Tests Specific Tests
- 14. Decontamination
- 15. Decontamination ā¢ Activated Charcoal ā¢ Single Dose ā¢ Reversibly adsorbs most ingested toxins ā¢ Indicated within 1 hr of ingestion ā¢ Major risk: pulmonary aspiration ā¢ 50 g (adults) or 1g/kg (child) Other Methods: ā¢ Induced Emesis ā¢ Gastric Lavalge ā¢ Whole Bowel Irrigation
- 16. CAUTION!! ā¢ Do not try Activated Charcoal for: ā¢ Hydrocarbons and Alcohols: Ethanol, Isopropyl Alcohol, Ethylene glycol, methanol ā¢ Metals: Lithium, Iron, Potassium, Lead, Arsenic, Mercury ā¢ Corrosives: Acids, Alkali
- 17. Enhanced Elimination ā¢ Increase the rate of removal of an agent with the aim of reducing the severity and duration of clinical intoxication ā¢ Only useful in poisoning with few agents that are characterised by: ā¢ Severe toxicity ā¢ Poor outcome despite good supportive care and antidote administration ā¢ Slow endogenous rates of elimination ā¢ Suitable pharmacokinetic properties
- 18. Techniques for Enhanced Elimination Urinary Alkalinisation ā¢ Alkaline urine promotes the ionisation of highly acidic drugs and prevents reabsorption ā¢ Sodium bicarbonate, bolus + infusion ā¢ Useful for Phenobarbitone, Salicylate Other methods: ā¢ Multiple Dose Activated Charcoal ā¢ Hemoperfusion ā¢ Hemodialysis ā¢ Plasmapheresis ā¢ Exchange Transfusion ā¢ Charcoal Hemoperfusion
- 19. Antidotes ā¢ Antidotes are drugs ā¢ Indication based upon a risk-benefit analysis ā¢ Administered only when therapeutic benefit exceeds: ā¢ Potential adverse effects ā¢ Cost and resource requirements. ā¢ An accurate risk combined with pharmaceutical knowledge of the antidote is essential to clinical decision-making.
- 20. Few Antidotesā¦ Poison/Overdose Antidote Organophosphate Atropine Atropine Physostigmine Methanol Ethanol and fomepizole Cyanide Thiosulfate Opioids Naloxone Beta agonists, Theophylline Esmolol (Beta-blocker)
- 21. Few Antidotesā¦ Poison/Overdose Antidote Digoxin Digoxin immune Fab Heparin Protamine Warfarin, Coumarins Vitamin K Benzodiazepines Flumazenil Paracetamol Acetylcysteine Iron and iron salts Desferioxamine Carbon monoxide Oxygen (Hyperbaric)
- 22. Disposition ā¢ Medical and Psychosocial disposition ā¢ A patient may be: ā¢ Discharged ā¢ Transferred ā¢ Referred ā¢ Emergency Observation Unit ā¢ Intensive Care Unit
- 23. Some Common Toxicological values Drug/Enzyme Normal Range (Ī¼g/mL) Phenytoin 10-20 Phenobarbitone 15-40 Paracetamol 10-20 Carbamazepine 4-12 Serum Cholinesterase 4000-11500
- 24. Lets try solving theseā¦ ā¢ A patientās blood sample was sent tested for serum paracetamol level and was found to be 300mg/dL. What is your diagnosis and how will you manage this case? ā¢ A patient with organophosphorus poisoning presented to you in Emergency Department. How will you manage the case?
Editor's Notes
- Acute toxicity involves harmful effects in an organism through a single or short-term exposure. Subchronic toxicity is the ability of a toxic substance to cause effects for more than one year but less than the lifetime of the exposed organism. Chronic toxicity is the ability of a substance or mixture of substances to cause harmful effects over an extended period, usually upon repeated or continuous exposure, sometimes lasting for the entire life of the exposed organism.
- Examples where early administration of an antidote is necessary to ensure a successful resuscitation include intravenous sodium bicarbonate in tricyclic antidepressant poisoning, naloxone in severe opioid intoxication digoxin-specific antibody fragments for patients with suspected digoxin intoxication with cardiovascular compromise. Antidotes during resuscitation: intravenous sodium bicarbonate in tricyclic antidepressant poisoning naloxone in severe opioid 1 intoxication digoxin-specific antibody fragments for patients with suspected digoxin intoxication with cardiovascular compromise
- Examples where early administration of an antidote is necessary to ensure a successful resuscitation include intravenous sodium bicarbonate in tricyclic antidepressant poisoning, naloxone in severe opioid intoxication digoxin-specific antibody fragments for patients with suspected digoxin intoxication with cardiovascular compromise. 1Toxidromes: Physiologically based abnormalities that are known to occur with specific classes of substances and typically are helpful in diagnosis
- Major causes of poisoning morbidity and mortality are acute effects of poison on cardiovascular, central nervous or respiratory systems: supportive care thus required Monitoring is essential to detect the progress of the intoxication and the timing of institution, escalation and withdrawal of supportive care and other measures.
- Major causes of poisoning morbidity and mortality are acute effects of poison on cardiovascular, central nervous or respiratory systems: supportive care thus required Monitoring is essential to detect the progress of the intoxication and the timing of institution, escalation and withdrawal of supportive care and other measures.
- Are either: Screening Tests: Qualitative and quantitative evaluation for active ingredient, its metabolite or other affected biochemical parameters May direct therapy Blood, Urine, Stool, Other body fluids e.g. gastric aspirate Specific Tests Should be requested selectively, if anticipated to assist risk assessment or management Includes Complete Blood Counts, Liver Function Test, Renal Function Test, Arterial Blood Gas Analysis, Chest X-ray
- High Hazard Potential: Not to be used routinely Clinical judgment based on potential benefits, potential risks and available resources Absorption virtually completed within 1 hr- so decontamination should be done as early as possible
- have specific indications, contraindications, optimal administration methods, monitoring requirements, appropriate therapeutic end-points and adverse effect profiles.