diagnosis and management of poisoning
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Diagnosis and management of poisoning
Agents involved in poisoning: National Poisons Information Service
(NPIS) enquiries
77%
11%
3% 2% 7%
Drug
Household
Industrial
Pesticide
Other
N = 25000
Patient age
0%
5%
10%
15%
20%
25%
30%
35%
40%
45%
50%
<5 yrs 5 - 9 yrs 10 - 14
yrs
15 - 19
yrs
20 - 49
yrs
>50 yrs
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
• Para-suicide
• Readily available agents
• Frequently in combination
• Frequently combined with alcohol
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?
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).
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?
Poisoning: clinical approachHistory
• Why?
• Family or interpersonal disagreement?
• Psychiatric symptoms or history?
• Sociopath?
• Serial self-harm?
Poisoning: clinical approachExamination
• Usually perfectly well or drunk
• Conscious level
• Integrity of airway
• Cardio- respiratory
• Urine output
Poisoning: clinical approachinvestigations
• 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
• 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
• 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 infusionStandard: 300 mg/kg over 20 hoursProlonged: 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
Ethanol Acetaldehyde Acetate
Alcohol dehydrogenase
Aldehyde dehydrogenase
Ethanol intoxication
• Central nervous system Excitation Obtunded
• Metabolic Hypoglycaemia Metabolic acidosis Fluid/electrolyte disturbances
Ethanol intoxication:clinical management
• 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 depressionHypoxia/anoxic brain damage
SaO2, PaO2
Naloxone (infusion)
• RhabdomyolysisCompartment syndrome/myoglobinuria
CPK
Benzodiazepines
• ComaOften prolonged (especially elderly)
Respiratory depression unusual unless
mixed overdose with other CNS depressants
Amphetamines/Ecstasy(MDMA)
• Agitation/delirium/coma
• Hypertension/tachycardia/mydriasis
• Hyperpyrexia
• AST/CPK elevated
• Rarely: DIC, hyponatraemia, multi-organ failure
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