ACUTE POISONING IN ADULTS

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ACUTE POISONING IN ADULTS

• Leilah Dare
• SpR Emergency Medicine

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Acute Poisoning in the Emergency Department

• Common - 3-5 of ED attendances
• 2000 Deaths per year
• Some of the highest rates of deliberate poisoning
  in Europe
• Often multiple drugs
• DONT FORGET ALCOHOL !!

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Summary of Lecture

• General Principles in the Management of ANY
  Poisoning
• Specific management options with certain
  substances
• Paracetamol
• Opiates (Heroin, Methadone, Morphine)
• Salicylates (Aspirin)
• Tricyclic Antidepressants (e.g Dothiepin)

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General Management -History

• Applies to ANY episode of Poisoning
• WHAT
• HOW MUCH (Ideally mg/Kg)
• WHEN
• WHAT ELSE (Including Alcohol)
• WHY
• Use Paramedics, friends, relatives, anyone!!

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General Management -1

• A (Airway)
• B (Breathing)
• C (Circulation)
• D (Disability-AVPU/ Glasgow Coma Scale)
• DEFG ( Dont ever forget the Glucose)
• GET A SET OF BASIC OBSERVATIONS

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General Management -2

• Use all your senses, search for the clues
• LOOK
• Track Marks
• Pupil Size
• FEEL
• Temperature, Sweating
• SMELL
• Alcohol

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Specific Management Options-1

• DECREASING DRUG ABSORPTION
• Gastric Lavage ( Unpopular - need to protect the
  airway, may push drug through pylorus into small
  bowel.)
• Absorbants ( Activated Charcoal , usually within
  1 hour of ingestion, longer repeated doses in
  drugs that delay gastric emptying e.g. Aspirin)

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Specific Management Options -2

• INCREASING DRUG ELIMINATION
• Alkaline Diuresis (Aspirin)
• Haemodialysis (Aspirin)

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Specific Management Options - 3

• ANTAGONISING THE EFFECTS OF THE POISON
• Desferrioxamine (IRON)
• Naloxone (OPIATES)
• N Acetylcysteine (PARACETAMOL)

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Specific Poisons- Paracetamol

• Commonest drug used
• 50 of all Self Poisoning Episodes
• 100- 200 deaths per year
• DANGEROUS AND PEOPLE DONT KNOW IT. YOU FEEL WELL
  AND THEN THE LIVER FAILURE SETS IN..

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Paracetamol-Normal Metabolism

• Paracetamol converted to
• N-Acetyl-p-benzoquinonamine (TOXIC)
• This is conjugated with Glutathione
• Glutathione stored in the body
• Produces a NON TOXIC metabolite

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Paracetamol Metabolism in Overdose

• Glutathione stores are used up by the excess
  Paracetamol
• Toxic Metabolite build up
• Binds IRREVERSIBLY to Hepatic Cell membranes
• Resulting in LIVER NECROSIS

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Paracetamol Overdose-management

• Initial ABC ( usually well systemically)
• Get a good history
• TIME TAKEN, AMOUNT
• Any other medication
• History of Liver disease
• N-Acetylcysteine. Shown to be advantageous if
  given in the first 10 hours

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N - Acetylcysteine

• Specific antidote used for Paracetamol
• Provides the Sulphydryl groups needed to increase
  the availability of Glutathione
• So that Body can turn the TOXIC metabolite into
  the non toxic form and prevent Liver Cell Damage
  and NECROSIS
• Problem Not shown to be effective after 15 hours

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Paracetamol Management

• Able to measure levels of Paracetamol in the
  blood.
• Helps to guide whether amount taken is enough to
  be Hepatotoxic
• IF IN DOUBT start treatment before the
  Paracetamol levels get back to save time

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Paracetamol Management-Pitfalls

• Patients with Liver Disease/ Alcoholics
• Depleted stores of Glutathione will start to get
  toxic build up sooner than healthy people
• Staggered Overdoses
• Levels unreliable
• After 15 hours- what do you do??

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Paracetamol Management

• TIMEBOMB WAITING TO HAPPEN
• IF HAVE LATE PRESENTATION HAVE TO MONITOR FOR
  IMPENDING LIVER FAILURE
• REFER TO SPECIALIST LIVER UNIT
• PEOPLE DIE FROM THIS

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Opiate Poisoning- Features

• Common (particularly in BRI)
• Heroin, Methadone, Analgaesics in Elderly
• Action on the mu receptors giving the effects in
  overdose.
• 1. PINPOINT PUPILS
• 2. RESPIRATORY DEPRESSION
• 3.COMA

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Opiate Overdose-Management

• INITIAL MANAGEMENT
• A
• B
• C
• D

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Opiate Overdose-Management 2

• NALOXONE
• Opioid antagonist
• High Affinity for the opiate receptors
• Little other effects
• Rapid onset
• Effects last 2-4 hrs, may need repeated doses
• Give I-M or I-V

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Salicylate (Aspirin) Poisoning

• Toxicity occurs due to disturbance in Acid-Base
  Balance
• 1. Respiratory Alkalosis
• 2. Metabolic Acidosis

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Aspirin Poisoning- mechanism 1

• 1.Direct stimulation of the respiratory centre
  makes you overbreathe. Hyperventilation and
  Respiratory Alkalosis.
• 2. Kidney attempts to compensate for the
  alkalosis by excreting alkali to give you a
  metabolic Acidosis
• 3. Aspirin inhibits the normal metabolic pathways

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Aspirin poisoning- mechanism 2

• 3. Aspirin inhibits the normal metabolic
  pathways, so you get failure of the normal
  metabolism of CHO, Fats and Protein.
• Build up of Organic Acids
• KETONES, LACTATE AND PYRUVATE
• CAUSES MORE METABOLIC ACIDOSIS
• METABOLIC ACIDOSIS, BAD NEWS

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Aspirin Poisoning -Clinical Features

• COMMON FEATURES
• Vomiting, Dehydration, Tinnitus, Vertigo
• Sweating, Bounding pulses, Hyperventilation
• UNCOMMON FEATURES
• Confusion, Disorientation, Coma, Convulsions
• Haematemesis, Hyperpyrexia, clotting
  abnormalities, renal failure

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Aspirin Overdose-Management

• Initial Supportive therapy. If small amounts and
  asymptomatic may need no treatment
• Management tailored according to the amount taken
• Able to take Salicylate levels to help guide
  treatment options

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Aspirin Management - General

• A
• B
• C
• D
• (EFG)

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Aspirin Management - Specific

• When extremely high levels of Aspirin have been
  ingested and the patients are symptomatic steps
  may be taken to-
• 1. DECREASE ABSORPTION
• 2. INCREASE DRUG ELIMINATION

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Aspirin- Decreasing absorption

• Activated Charcoal
• Given in those who have taken more than 250mg/Kg
  body weight less than 1 hour ago
• Gastric Lavage
• May be considered in those who have taken more
  than 500mg/kg body less than 1 hour ago. Steps
  must be taken to protect the airway

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Aspirin-Increasing Drug Elimination

• Urinary Alkalinisation
• If you increase urinary pH from 5 to 8 there is a
  10-20 fold increase in the renal salicylate
  clearance
• This is done by giving an infusion of Sodium
  Bicarbonate. Care must be taken because this in
  itself is dangerous and can cause severe Acid
  Base Disturbances

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Aspirin- Increasing Drug Elimination

• HAEMODIALYSIS
• Used in severe life threatening overdose
• Aims to correct the Acid Base disturbances while
  removing the Salicylate

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Tricyclic Antidepressants

• Seen relatively frequently
• Can be fatal
• Can be very symptomatic, effects made worse by
  alcohol
• Main effects are on the Heart and Brain
• Effects are
• 1. Anticholinergic
• 2. Quinidine like

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TCA Overdose- Clinical features

• ANTICHOLINERGIC EFFECTS
• Dry Mouth, Dry Eyes, Dilated Pupils, Urinary
  Retention, Blurred Vision, Dizziness,
  Palpitations, Pyrexia without sweating
• CNS Effects- Confusion, Delerium, Coma,
  Convulsions, Myoclonus and Respiratory Depression

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TCA Overdose Clinical Features

• Cardiac Toxicity (quinidine effects)
• Heart Block, Asystole, Bradycardia, Tachycardia,
  Ventricular Dysrythmias
• ECG Changes - broadening of QRS complex, Widened
  QT Interval

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TCA Overdose- Management 1

• Mainstay of initial management is Supportive. Try
  not to give other drugs ontop with a few specific
  exceptions
• A- May need intubating
• B
• C- Give IV fluids if low BP
• D -Control convulsions with Diazepam

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TCA Overdose Management 2

• Activated Charcoal if more than 4 mg/Kg within 1
  hour.
• N.B WATCH OUT FOR THE AIRWAY
• Correct Hypoxia with Oxygen
• Correct Acidosis with Na Bic
• Correct any arrythmias with Na Bic (i.e start by
  controlling the acid base disturbance)

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QUESTIONS

• ?

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SUMMARY

• Get as much history as you can, know your enemy
• Mainstay of any poisoning is Supportive
• Dont Forget the ABC
• For specific substances there maybe antidotes
• For Specific circumstances consider decreasing
  the absorption or increasing the elimination of
  the drug.