Drug Overdose DRUG OVERDOSE Management Principles and Decontamination

Drug Overdose DRUG OVERDOSE Management Principles and Decontamination

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

Examination LOC GCS w uniformly used w developed for prognosticating head injuries w verbal and pain response most useful in DSPs • AVPU Vital signs w Temp/PR/BP/RR/Sp. O 2

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

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

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

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

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

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

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

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

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

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

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

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

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. ”

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

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

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

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

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

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

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

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

Whole bowel irrigation w w w 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

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

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