Objectives Provide a general overview of toxicology How to approach the poisoned patient Understanding common toxidromes
What is Toxicology What is it not a poison? All things are poison and nothing is without poison. Solely the dose determines that a thing is not a poison. -Paracelsus (1943-1541), the Renaissance Father of Toxicology, in his Third defence
Why do people OD? Significant portion intend to die at time of overdose Most want to escape an intolerable situation or state of mind Small minority of patients want to punish someone or make someone feel guilty Mental health difficulties particularly, depression, ETOH or substance misuse, and personality disorders are frequently seen Inability to tolerate life stressor or events, relationship breakdowns, anniversaries of bereavement, ect. Mitchell, A. Dennis, M. Self harm and attempted suicide in adults: 10 practical questions and answers for emergency department staff. Emerg Med J, 2006: 26, 251-255
What Drugs do they OD on? ETOH Paracetamol Benzo’s Antipsychotics Antidepressants Antiepileptic Opiods And many many more!!!
The ECG in TOX Valuable inexpensive screening tool QRS widening R/T sodium channel blockade, common with TCA overdose QT prolongation is a potassium channel effect associated with TDP, common in some antidepressant, antiarrythmics, & antipsychotic overdoses.
Urine Drug Screen Why don’t we do it? In general it rarely if ever changes management. Expensive Takes 1-2 days to get back When would we consider it?
Antidotes Limited number of antidotes available for limited number of poisonings. Common Antidotes: NAC Naloxone Sodium Bicarb Digoxin Immune Fab 5. Octreotide
Common Complications in the Critically Poisoned Patient Aspiration Pneumonia ARDS ARF DVT/PE Rhabdomyolysis Compartment Syndrome Hepatotoxicity
Disposition The patients journey can be: RESUS ICU Assessment Obs ward Psych Or patients with DSP need Pysch R/V
Poisoning in Children Most paediatric poisoning are benign, as children generally ingest small quantities. Always base your assessment on worse case scenario: The time of ingestion is assumed to be the latest possible time Assume all missing or unaccounted for agent(s) have been ingested Do not attempt to account for spillage, which is difficult to estimate If more than child involved, it is assumed that each child ingested all the missing or unaccounted for agent(s)
Management of child who ingest unidentified poison Admit for minimum of 12-hour observation Ensure health care facility can cope Defer IV access until evidence of toxicity Check BSL at presentation and on D/C Monitor GCS & vital signs Cardiac monitor if decreased GCS or abnormal vital signs D/C during daylight hours
Poisoning in Pregnancy Need to assess risk to fetus or infant if lactating Management rarely differs from non pregnant patients Agents that pose greater risk to fetus: Carbon Monoxide Methaemoglobin-inducing agents Lead Salicylates
Need to provide risk/benefit analysis if breastfeeding is to continue as the mother recovers
Poisoning in the Elderly Can be challenging to manage R/T co-morbidities, decreased physiological reserve, and multiple prescribed medications. Higher complication rate and longer hospital admission: Pharmacokinetic changes: Delayed gastrointestinal absorption Decreased protein binding ^ free drug levels Reduced hepatic metabolic function Decreased GFR which impairs elimination
Common poisoning in the Elderly Digoxin Metformin Lithium Disposition= Generally elderly patients end up in Gen Med units for prolonged periods of care
Coma Patients presenting with coma have generally overdosed on a drug with CNS depressant effects. Can be caused by secondary effects: Hypoxaemia Hypoglcaemia Hyponatraemia Hypotension Seizures Cerebral oedema
Coma Management RRSIDEAD Good supportive care & airway management Treat secondary effects Look at what else can cause coma Neurotrauma Metabolic encepathopathy Menigioencephalopathy Space occupying lesion Patients generally go to ICU, till conscious states improve Look for complication’s (Asp Pneumonia)
Why do we use Diazepam so much in TOX? Good safety profile Long half life Controls agitation well Used to treat toxic seizures Generally drug of choice in managing withdrawals Dose adult 5-10mg, child 0.1-0.3mg/kg/dose every 3-5mins
Anticholinergic Syndrome Results from the competitive, reversible blockade of central & peripheral cholinergic blockade. Is potentially life threatening Diagnosed clinically by agitated delirium and peripheral muscarinic blockade History of ingestion of known anticholinergic agent
Remember the saying!!! Hyperthermia (HOT as a hare) Flushed (RED as a beet) Dry Skin (DRY as a bone) Dilated pupils (Blind as a bat) Delirium, hallucinations (Mad as a hatter) Tachycardia Urinary Retention
Management Good Supportive Care IV fluids IDC Diazepam to control agitation Avoid drugs with anticholinergic effects Antidote:
Reverse anticholinergic delirium in selected patients that don’t respond to benzo’s
Serotonin Syndrome Clinical diagnosis based on history of ingestion of one or more serotonergic agents, the presence of characteristic symptoms, & high index of suspicion Clinical features fall into 3 categories CNS Autonomic Neuromuscular
Managing Serotonin Syndrome RRSIDEAD Check BSL Check temp >38.5 continuous core monitoring, temp > 39.5 paralysis and intubate Give benzo’s to achieve gentle sedation HT & tachycardia generally respond to benzo’s, if refractory trial of GTN infusion Antidote: Cyproheptadine, given orally or via NG