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