Diagnosis and management of poisoning

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Diagnosis and management of poisoning
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Agents involved in poisoning National Poisons
Information Service (NPIS) enquiries
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Patient age
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Age and poisonings

• Children (lt 5years)
• Accidental/household products/usually low
  toxicity
• Adults
• Usually para-suicide with readily available drugs
• Most need little/no medical intervention
• Elderly
• Often significant psychiatric problems
• Access to more prescription drugs of higher
  toxicity
• Tolerate poisonings less well

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Common agents in adult overdoses

• OTC drugs (paracetamol/NSAID/vitamins)
• Alcohol
• Pyschotropic drugs (TCAs, SSRIs, major
  tranquillisers, benzodiazepines, lithium)
• Street drugs (heroin)

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Common features in adult overdoses

• Para-suicide
• Readily available agents
• Frequently in combination
• Frequently combined with alcohol

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Poisoning clinical approachHistory

• What has the patient taken and when?
• Where and under what circumstances has the
  self-harm occurred?
• Why has the patient self-harmed?
• Is this a repeat episode?
• Previous psychiatric or sociopathic history?

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Poisoning clinical approachHistory

• The type and quantity of drug(s) taken is (are)
  almost always known.
• (Volunteered by patient, known to
  relatives/friends or empty bottles).

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Poisoning clinical approachHistory

• Was the patient likely to be found quickly after
  the episode of self-harm?
• Considered or impetuous episode of self- harm?
• Drunk?
• Suicide note?

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Poisoning clinical approachHistory

• Why?
• Family or interpersonal disagreement?
• Psychiatric symptoms or history?
• Sociopath?
• Serial self-harm?

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Poisoning clinical approachExamination

• Usually perfectly well or drunk
• Conscious level
• Integrity of airway
• Cardio- respiratory
• Urine output

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Poisoning clinical approachinvestigations

• Routinely, SaO2, U/E/LFT, FBC, ECG
• Specific toxicological tests
• Unknown drug screens

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Diagnosis of poisoningspecific toxicological
tests

• Prognostic information
• Need for elimination therapy
• Need for antidote

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Specific toxicological investigations

• Paracetamol
• Aspirin
• Iron
• Theophylline
• Lithium
• Digoxin
• (Ethanol/alcohols/glycols)

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Repeated drug levels

• Aspirin
• Theophylline
• Lithium

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Diagnosis of poisoning unknown drug screens

• Usually not available in appropriate time scale
• Usually of little or no clinical value, so
  discuss with laboratory/NPIS
• Coma is not an indication for drug screening
• Consider in those who are thought to have
  overdosed with unknown drugs and are clinically
  unstable
• Save urine and blood for critically ill cases (HM
  Coroner)

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Poisoning clinical approachso what do I do
next

• Is this serious?
• What additional tests do I need?
• Whats the clinical management?

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Poisoning clinical approachso what do I do
next

• TOXBASE
• www.spib.axl.co.uk/

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National Poisons Information Service (NPIS)

• Managed network of centres
• Belfast, Birmingham, Cardiff, Edinburgh, London,
  Newcastle
• TOXBASE as first tier database
• Single phone number 0870 600 6266

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Clinical management of the poisoned patient

• Observation/supportive
• Techniques to prevent drug absorption
• Techniques to eliminate the drug(s)
• Antidotes

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Gut decontamination

• Syrup of ipecac
• Gastric lavage
• Activated charcoal

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Elimination techniques

• Repeat dose activated charcoal
• Urinary alkalinisation/acidification
• Dialysis

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Antidotes

• N-acetyl cysteine (Paracetamol)
• Naloxone (Opiates)
• Flumazenil (Benzodiazepines)
• Desferrioxamine (Iron)
• Digibind (Digoxin)
• Pralidoxime (Organophosphates)

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Some common clinical presentations
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Paracetamol
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Paracetamolstandard management

• Toxic paracetamol concentration
• N acetyl cysteine (NAC, Parvolex 300mg/Kg over 20
  hours
• Check INR/creatinine before discharge

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Paracetamol

• High-risk patients
• Alcoholics
• Co-prescription enzyme-inducing drugs
• Starvation/anorexia

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Paracetamol late presentation

• Prolonged NAC infusion
• Standard 300 mg/kg over 20 hours
• Prolonged standard course
• (150 mg/kg over 16 hours)n
• Monitor urine output
• Monitor INR
• Monitor blood glucose

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Paracetamol prognosis

• Usual biochemical LFTs are not related to outcome
• Poor prognosis (80 - 90 mortality) if
• pH lt 7.3 or
• creatinine gt 300 ?mol/L PT gt 100 secs
• grade 3/4 encephalopathy

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Ethanol

• Very common
• Clinical effects of any given blood ethanol
  concentration vary with prior experience of
  ethanol use/abuse

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Alcohol dehydrogenase metabolism
Alcohol dehydrogenase
Aldehyde dehydrogenase
Ethanol
Acetaldehyde
Acetate
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Ethanol intoxication

• Central nervous system
• Excitation
• Obtunded
• Metabolic
• Hypoglycaemia
• Metabolic acidosis
• Fluid/electrolyte disturbances

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Ethanol intoxicationclinical management

• Maintain airway patency
• Avoid inhalation of vomitus
• Intravenous fluids
• Monitor blood glucose and pH

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Tricyclic anti-depressants

• Coma/convulsions/cardiac dysrrhythmias
• Serious overdoses coma, ECG abnormalities (QRS
  prolongation), serum total tricyclic
  anti-depressant levels gt 1000 ?g/L

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Opiates

• Respiratory depression
• Hypoxia/anoxic brain damage
• SaO2, PaO2
• Naloxone (infusion)
• Rhabdomyolysis
• Compartment syndrome/myoglobinuria
• CPK

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Benzodiazepines

• Coma
• Often prolonged (especially elderly)
• Respiratory depression unusual unless
• mixed overdose with other CNS depressants

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Amphetamines/Ecstasy(MDMA)

• Agitation/delirium/coma
• Hypertension/tachycardia/mydriasis
• Hyperpyrexia
• AST/CPK elevated
• Rarely DIC, hyponatraemia, multi-organ failure