Diagnosis and management of
poisoning
Agents involved in poisoning:
National Poisons Information Service
(NPIS) enquiries
N = 25000
3% 2%
7%
11%
Drug
Household
Industrial
Pesticide
Other
77%
Patient age
50%
45%
40%
35%
30%
25%
20%
15%
10%
5%
0%
<5 y r s
5 - 9 yrs
10 - 14
15 - 19
20 - 49
yrs
yrs
yrs
>5 0 y r s
Age and poisonings
• Children (< 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
Common agents in adult
overdoses
• OTC drugs: (paracetamol/NSAID/vitamins)
• Alcohol
• Pyschotropic drugs: (TCAs, SSRIs, major
tranquillisers, benzodiazepines, lithium)
• ‘Street’ drugs: (heroin)
Common features in adult
overdoses
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•
•
•
Para-suicide
Readily available agents
Frequently in combination
Frequently combined with alcohol
Poisoning: clinical approach
History
• 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?
Poisoning: clinical approach
History
• The type and quantity of drug(s) taken is
(are) almost always known.
(Volunteered by patient, known to
relatives/friends or empty bottles).
Poisoning: clinical approach
History
• Was the patient likely to be found quickly
after the episode of self-harm?
• Considered or impetuous episode of selfharm?
• Drunk?
• Suicide note?
Poisoning: clinical approach
History
•
•
•
•
•
Why?
Family or interpersonal disagreement?
Psychiatric symptoms or history?
Sociopath?
Serial self-harm?
Poisoning: clinical approach
Examination
•
•
•
•
•
Usually perfectly well or drunk
Conscious level
Integrity of airway
Cardio- respiratory
Urine output
Poisoning: clinical approach
investigations
• Routinely, SaO2, U/E/LFT, FBC, ECG
• Specific toxicological tests
• Unknown drug screens
Diagnosis of poisoning:
specific toxicological tests
• Prognostic information
• Need for elimination therapy
• Need for antidote
Specific toxicological investigations
•
•
•
•
•
•
•
Paracetamol
Aspirin
Iron
Theophylline
Lithium
Digoxin
(Ethanol/alcohols/glycols)
Repeated drug levels
• Aspirin
• Theophylline
• Lithium
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)
Poisoning: clinical approach
‘so what do I do next’
• Is this serious?
• What additional tests do I need?
• What’s the clinical management?
Poisoning: clinical approach
‘so what do I do next’
• TOXBASE
• www.spib.axl.co.uk/
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
Clinical management of the
poisoned patient
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•
•
•
Observation/supportive
Techniques to prevent drug absorption
Techniques to eliminate the drug(s)
Antidotes
Gut decontamination
• Syrup of ipecac
• Gastric lavage
• Activated charcoal
Elimination techniques
• Repeat dose activated charcoal
• Urinary alkalinisation/acidification
• Dialysis
Antidotes
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•
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N-acetyl cysteine (Paracetamol)
Naloxone (Opiates)
Flumazenil (Benzodiazepines)
Desferrioxamine (Iron)
Digibind (Digoxin)
Pralidoxime (Organophosphates)
Some common clinical presentations
Paracetamol
Paracetamol:
standard management
• ‘Toxic’ paracetamol concentration
• N acetyl cysteine (NAC, Parvolex
300mg/Kg over 20 hours
• Check INR/creatinine before discharge
Paracetamol
• ‘High-risk’ patients:
Alcoholics
Co-prescription enzyme-inducing drugs
Starvation/anorexia
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
Paracetamol: prognosis
• Usual biochemical LFTs are not related to
outcome
• Poor prognosis (80 - 90% mortality) if:
 pH < 7.3 or
 creatinine > 300 mol/L + PT > 100 secs +
grade 3/4 encephalopathy
Ethanol
• Very common
• Clinical effects of any given blood ethanol
concentration vary with prior experience of
ethanol use/abuse
Alcohol dehydrogenase
metabolism
Alcohol
dehydrogenase
Ethanol
Aldehyde
dehydrogenase
Acetaldehyde
Acetate
Ethanol intoxication
• Central nervous system
Excitation
Obtunded
• Metabolic
Hypoglycaemia
Metabolic acidosis
Fluid/electrolyte disturbances
Ethanol intoxication:
clinical management
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•
•
•
Maintain airway patency
Avoid inhalation of vomitus
Intravenous fluids
Monitor blood glucose and pH
Tricyclic anti-depressants
• Coma/convulsions/cardiac dysrrhythmias
• Serious overdoses: coma, ECG
abnormalities (QRS prolongation), serum
total tricyclic anti-depressant levels > 1000
g/L
Opiates
• Respiratory depression
Hypoxia/anoxic brain damage
SaO2, PaO2
Naloxone (infusion)
• Rhabdomyolysis
Compartment syndrome/myoglobinuria
CPK
Benzodiazepines
• Coma
Often prolonged (especially elderly)
Respiratory depression unusual unless
mixed overdose with other CNS depressants
Amphetamines/Ecstasy(MDMA)
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•
•
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•
Agitation/delirium/coma
Hypertension/tachycardia/mydriasis
Hyperpyrexia
AST/CPK elevated
Rarely: DIC, hyponatraemia, multi-organ
failure