Drug Overdose

1. Drug Overdose DRUG OVERDOSE Management Principles and Decontamination

2. History Speak to: • patient • relatives • ambulance officers Ask • what drug was ingested • when • how much

3. Examination LOC  GCS • uniformly used • developed for prognosticating head injuries • verbal and pain response most useful in DSPs • AVPU Vital signs • Temp/PR/BP/RR/SpO2

4. Examination Mini-Neuro • Pupil size and reaction • Reflexes • Gross assessment of muscle tone Chest/CVS as appropriate but low yield BS may be  in anticholinergic toxidrome

5. Investigation BSL • mandatory if  LOC ECG • always done • findings very specific QRS complex • indicative of Na+ channel blockade if prolonged

6. Investigation • Normal QRS is < 100 ms QT interval • <420 ms male <440 children <450 female • may be prolonged in certain poisonings • neuroleptics esp. thioridazine QT or QTc ? • Standardises QT to a rate of 60 bpm • only useful if heart rate <70 or >50

7. Investigation Concentrations are useful if suggestion of poisoning with • salicylates • paracetamol • lithium • valproate • theophylline No use as a screening tool

8. Investigation ABG Useful in assessing ventilatory status Useful if ingestion can cause metabolic upset: (VBG) • salicylate • metformin OR • if patient needs serum or urinary alkalinisation

9. Investigation Miscellaneous: • CXR if aspiration suspected • CT brain if story not c/w clinical findings • CK if unconscious for some time • K+ in digoxin poisoning

10. Close attention to ABC and supportive care is all that is required to manage MOST drug overdoses • GCS/vital signs/mini neuro and ECG are only tests/investigations likely to alter management with a few notable exceptions

11. Treatment May be specific antidote • NAC in paracetamol poisoning May be general/empiric • decontamination • coma cocktail • generous IV fluid replacement

12. Treatment Coma cocktail • Dextrose/Thiamine/Naloxone/Flumazenil Problems • hypoglycaemia  can be assessed with BM stix • Naloxone  can precipitate acute withdrawal • Flumazenil  may complicate further seizure management

13. Decontamination When should patient be decontaminated? risk of morbidity and/or mortality associated with ingestion What type of decontamination should be used? Depends on clinical circumstances and other treatment options

14. Decontamination • Syrup of Ipecac • Gastric lavage • Activated charcoal • multi dose • with cathartic • Whole bowel irrigation

15. Where is the Evidence ? Based on • Animal studies • Volunteer studies • clinical studies Difficulty due to • serious ingestions excluded • conflicting results

16. Where is the Evidence Position statements released in 1997 by AACT and EAPCCT “Overall the mortality from acute poisoning is less than 1 % and the challenge for clinicians is to identify promptly those who are at most risk of developing serious complications and who might potentially benefit, therefore, from gastrointestinal decontamination.”

17. Syrup of Ipecac • Plant extract previously abused by bullimics • needs to be given EARLY • induces vomiting by gastric and central mechanism Contraindicated in • unprotected airway • corrosive • very little evidence for or against • possible role in the home for children

18. Gastric lavage • No studies demonstate efficacy even < 60 min.s • Studies exclude serious poisonings Contraindicated: • dodgy airway reflexes • corrosives • hydrocarbon

19. Gastric lavage • May increase risk of aspiration • May lead to pharyngeal injury • alleged to increase absorption in some cases • Has lead to significant return of ingestants up to 12 hours post ingestion(salicylates) Indication • Serious life threatening poisoning with well protected airway (level IV evidence)

20. Activated charcoal • Will adsorb many toxins in GI tract BUT: • Alcohols • Li+, Fe 2+ (probably all alkali metals) • Ratio should be 10:1 AC:toxin • Evidence from volunteer studies that absorption will be  if < 60 min.s • Little to suggest benefits outcome clinically or absorption post 60 min.s DO NOT GIVE ROUTINELY

21. Activated charcoal • Beware the unprotected airway or aspiration risk • dose is 50g adult, 1g/kg in a child Cathartics • Alleged to increase bowel transit time of toxin • Evidence only from animal and volunteer studies • Unlikely to benefit

22. Multi dose activated charcoal • Works by • GI dialysis • drugs with significant enterohepatic circulation • examples: • theophylline • anticonvulsants • salicylates • digoxin

23. Multi dose activated charcoal • Good, though indirect evidence of effect in digoxin poisoning • 50g q 6 hrly OR by NG infusion if intubated • up to 1g/kg suggested for serious theophylline poisonings • Justifies “late” instigation of charcoal

24. Whole bowel irrigation Used for • SR/EC preparations • when charcoal is ineffective • No controlled clinical studies to back up use physically speeds up transit through GI tract single dose charcoal given prior to starting

25. Whole bowel irrigation • PEG ELS (“go-lytely”) is used  does not cause significant water/electrolyte disturbance • frequently causes vomiting, requires NGT • airway must be protected • ileus is CI but has been reversed with neostigmine • dose is 15-20 mls/kg/hr • endpoint is clear rectal effluent, median time to achieve this is 6 hours

26. Duty of Care • Ingestion of an overdose renders a patient incompetent • If requires hospitalisation for physical effects of drug overdose • keep under duty of care • If no medical issues and attempts to leave  Schedule II

27. Take home messages • History, focused exam and a few tests, supportive care +/- period of observation is appropriate management for most DSPs • Ipecac is never used, gastric lavage occasionally • Charcoal is only given if likely to benefit • Patients receiving decontamination must have airway protection