Agents involved in poisoning: National Poisons Information Service (NPIS) enquiries
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)
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 Aldehyde dehydrogenase Ethanol Acetaldehyde Acetate
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 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) • Agitation/delirium/coma • Hypertension/tachycardia/mydriasis • Hyperpyrexia • AST/CPK elevated • Rarely: DIC, hyponatraemia, multi-organ failure