Toxicology
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  • 1. Approaching the Poisoned Patient!!
  • 2. Objectives
    Provide a general overview of toxicology
    How to approach the poisoned patient
    Understanding common toxidromes
  • 3. What is Toxicology
    What is it not a poison? All things are poison and nothing is without poison. Solely the dose determines that a thing is not a poison.
    -Paracelsus (1943-1541), the Renaissance Father of Toxicology, in his Third defence
  • 4. Why do people OD?
    Significant portion intend to die at time of overdose
    Most want to escape an intolerable situation or state of mind
    Small minority of patients want to punish someone or make someone feel guilty
    Mental health difficulties particularly, depression, ETOH or substance misuse, and personality disorders are frequently seen
    Inability to tolerate life stressor or events, relationship breakdowns, anniversaries of bereavement, ect.
    Mitchell, A. Dennis, M. Self harm and attempted suicide in adults: 10 practical questions and answers for emergency department staff. Emerg Med J, 2006: 26, 251-255
  • 5. What Drugs do they OD on?
    ETOH
    Paracetamol
    Benzo’s
    Antipsychotics
    Antidepressants
    Antiepileptic
    Opiods
    And many many more!!!
  • 6. Risk Assessment
    RRSIDEAD Approach
    Resuscitation
    Risk Assessment
    Supportive Care & Monitoring
    Investigations
    Decontamination
    Enhanced Elimination
    Antidotes
    Disposition
  • 7. Resuscitation
    Airway
    Breathing
    Circulation
    Control seizures
    Correct hypoglycaemia
    Correct hyperthermia
    Consider resuscitation antidotes
  • 8. Risk Assessment
    Agent
    Dose
    Time since ingestion
    Clinical features and course
    Patient factors
    Geographical location
  • 9. Supportive Care & Monitoring
    Supportive Care
    Airway: Intubation
    Breathing: O2, Ventilation
    Circulation: IVIH, Inotropes, Defib or pacing
    Sedation: Titrate Benzo’s
    Seizure control/prophylaxis: Titrate Benzo’s
    Metabolic: control pH, normoglycaemia
    Fluids & Electrolytes: Monitor
    Renal function: hydrate, haemodialysis
    General: Bladder care? IDC, Nutrition, DVT & Stress ulcerprophylaxis, PAC, Monitor mental state
  • 10. Can good supportive care can be done at home?
  • 11. Supportive Care & Monitoring
    Monitoring & investigation:
    12 lead ECG
    Paracetamol Level
    BSL below 4 correct with D50
    Temp above 38.5 requires continuous monitoring
  • 12. Drug Levels
  • 13.
  • 14. The ECG in TOX
    Valuable inexpensive screening tool
    QRS widening R/T sodium channel blockade, common with TCA overdose
    QT prolongation is a potassium channel effect associated with TDP, common in some antidepressant, antiarrythmics, & antipsychotic overdoses.
  • 15. Urine Drug Screen
    Why don’t we do it?
    In general it rarely if ever changes management.
    Expensive
    Takes 1-2 days to get back
    When would we consider it?
  • 16. Gastrointestinal Decontamination
    Methods:
    • Induced Emesis (Syrup of ipecac)
    • 17. Gastric Lavage
    • 18. Activated Charcoal
    • 19. Whole Bowel Irrigation
    Activated charcoal has most benefits in a limited number of poisoning, other methods have limited if any evidence to support their use.
  • 20. Enhanced Elimination
    Multiple-dose activated charcoal
    Urinary alkalinisation
    Haemodialysis and haemofiltration
    Charcoal haemoperfusion
  • 21. Antidotes
    Limited number of antidotes available for limited number of poisonings.
    Common Antidotes:
    NAC
    Naloxone
    Sodium Bicarb
    Digoxin Immune Fab
    5. Octreotide
  • 22. Common Complications in the Critically Poisoned Patient
    Aspiration Pneumonia
    ARDS
    ARF
    DVT/PE
    Rhabdomyolysis
    Compartment Syndrome
    Hepatotoxicity
  • 23. Disposition
    The patients journey can be:
    RESUS
    ICU
    Assessment
    Obs ward
    Psych
    Or patients with DSP need Pysch R/V
  • 24. Poisoning in Children
    Most paediatric poisoning are benign, as children generally ingest small quantities.
    Always base your assessment on worse case scenario:
    The time of ingestion is assumed to be the latest possible time
    Assume all missing or unaccounted for agent(s) have been ingested
    Do not attempt to account for spillage, which is difficult to estimate
    If more than child involved, it is assumed that each child ingested all the missing or unaccounted for agent(s)
  • 25. 2 tablets that can KILL a 10kg toddler
  • 26. Management of child who ingest unidentified poison
    Admit for minimum of 12-hour observation
    Ensure health care facility can cope
    Defer IV access until evidence of toxicity
    Check BSL at presentation and on D/C
    Monitor GCS & vital signs
    Cardiac monitor if decreased GCS or abnormal vital signs
    D/C during daylight hours
  • 27. Poisoning in Pregnancy
    Need to assess risk to fetus or infant if lactating
    Management rarely differs from non pregnant patients
    Agents that pose greater risk to fetus:
    Carbon Monoxide
    Methaemoglobin-inducing agents
    Lead
    Salicylates
    • Need to provide risk/benefit analysis if breastfeeding is to continue as the mother recovers
  • Poisoning in the Elderly
    Can be challenging to manage R/T co-morbidities, decreased physiological reserve, and multiple prescribed medications.
    Higher complication rate and longer hospital admission:
    Pharmacokinetic changes:
    Delayed gastrointestinal absorption
    Decreased protein binding ^ free drug levels
    Reduced hepatic metabolic function
    Decreased GFR which impairs elimination
  • 28. Common poisoning in the Elderly
    Digoxin
    Metformin
    Lithium
    Disposition= Generally elderly patients end up in Gen Med units for prolonged periods of care
  • 29. Toxidromes
  • 30. Coma
    Patients presenting with coma have generally overdosed on a drug with CNS depressant effects.
    Can be caused by secondary effects:
    Hypoxaemia
    Hypoglcaemia
    Hyponatraemia
    Hypotension
    Seizures
    Cerebral oedema
  • 31. Coma Management
    RRSIDEAD
    Good supportive care & airway management
    Treat secondary effects
    Look at what else can cause coma
    Neurotrauma
    Metabolic encepathopathy
    Menigioencephalopathy
    Space occupying lesion
    Patients generally go to ICU, till conscious states improve
    Look for complication’s (Asp Pneumonia)
  • 32. Why do we use Diazepam so much in TOX?
    Good safety profile
    Long half life
    Controls agitation well
    Used to treat toxic seizures
    Generally drug of choice in managing withdrawals
    Dose adult 5-10mg, child 0.1-0.3mg/kg/dose every 3-5mins
  • 33. Anticholinergic Syndrome
    Results from the competitive, reversible blockade of central & peripheral cholinergic blockade.
    Is potentially life threatening
    Diagnosed clinically by agitated delirium and peripheral muscarinic blockade
    History of ingestion of known anticholinergic agent
  • 34. Types of Anticholinergic Agents
    Antipakinson drugs (benztropine, amantadine)
    Antihistamines (prometazine, doxylamine)
    Antitussives (dextromethorphan)
    Antidepressants (TCA)
    Antipsychotic agents including atypical (Haloperidol, olazapine, Quetiapine)
    Anticonvulsant agents (carbamazapine)
    Motion sickness agents (hyoscine-scopolamine)
    Antimuscarinic agents (Atropine)
    Topical ophthalmological agents
    Bronchodilators (Ipratropium)
    Urinary antispasmodic agents (oxybutynin)
    Muscle relaxants
    Plants & herbal remedies (Selected mushrooms)
  • 35. Clinical Features of Anticholinergic Syndrome
  • 36. Remember the saying!!!
    Hyperthermia (HOT as a hare)
    Flushed (RED as a beet)
    Dry Skin (DRY as a bone)
    Dilated pupils (Blind as a bat)
    Delirium, hallucinations (Mad as a hatter)
    Tachycardia
    Urinary Retention
  • 37. Management
    Good Supportive Care
    IV fluids
    IDC
    Diazepam to control agitation
    Avoid drugs with anticholinergic effects
    Antidote:
    • Physostigimine
    • 38. Reverse anticholinergic delirium in selected patients that don’t respond to benzo’s
  • Serotonin Syndrome
    Clinical diagnosis based on history of ingestion of one or more serotonergic agents, the presence of characteristic symptoms, & high index of suspicion
    Clinical features fall into 3 categories
    CNS
    Autonomic
    Neuromuscular
  • 39. Clinical features of serotonin syndrome
  • 40. Life threatening serotonin syndrome
    Characterised by:
  • Agents implicated in serotonin syndrome
    SSRIs (fluoxetine, setraline, paroxetine)
    SNRIs (venlafaxine, citalopram, bupropion)
    TCAs (amitriptyline, dothiep)
    MAOIs (phenelzine, moclobemide)
    Lithium
    Analgesic (pethidine, tramadol, dextromethorphan)
    Antiemetics (metaclopramide, ondansetron)
    Anticonvulsants (valproic acid)
    Drugs of abuse (amphetamine, MDMA)
  • 46. Managing Serotonin Syndrome
    RRSIDEAD
    Check BSL
    Check temp >38.5 continuous core monitoring, temp > 39.5 paralysis and intubate
    Give benzo’s to achieve gentle sedation
    HT & tachycardia generally respond to benzo’s, if refractory trial of GTN infusion
    Antidote: Cyproheptadine, given orally or via NG
  • 47. The Tox Bible
  • 48. THE END!!