toxicology for medical students

Toxicology for Medical Students

Dr Kent RobinsonEmergency Staff Specialist

Liverpool and Campbelltown Hospital's

OBJECTIVES

• Understand basic approach to the poisoned patient.

• Recognose the major toxidromes.

• Apply your knowledge to clinical cases.

Approach to Poisoned Patient

• Supportive care is the mainstay of therapy.

• Decontamination of the patient is now rarely indicated.

• In specific situations, antidotes may used in the management of the poisoned patient.

Case 1

• 21 year old female - found down at home

• Drug paraphenalia found next to patient

• Pinpoint pupils, GCS 3, cyanotic

Case 1

• Naloxone 2 mg x 2 dose intravenous - no response

• O2 therapy, IPPV

• How would you manage this patient?

Case 1

• Assess and manage ABC's

• Disability - check BSL

• Reading "low on glucometer"

• Treated with dextrose 25 g iv, GCS to 15/15

Teaching Point

In any patient with altered mental status, always check a BSL

Case 2

• 41 year old male brought in from police cells

• Patient states he has taken overdose of diazepam

• Ataxic and drowsy

• Vital signs T 39, P 140 (ST), BP 90/60

• Pupils fixed and dilated

• Dry, warm skin, urinary retention

Case 2• Is this presentation consistent with the

stated overdose?

• What toxidrome is the patient exhibiting?

• What drugs are likely to cause this problem?

• How would you manage the patient?

Anticholinergic Toxidrome

• Antihistamines

• Antipsychotics

• Anticonvulsants

• Antidepressants

• Antispasmodics

• Antimuscarincs

• Plants - Datura, Mushrooms

Case 2 - Management

• Assess and manage ABC's

• Sedation - benzodiazepines

• One to one nursing care

• Intravenous fluids for tachycardia and hypotension

• Insertion of IDC

• Consider physostigmine if pure anticholinergic overdose.

Teaching Point

In patients who present with a drug overdose, always assume that they may have taken drugs other than what they

have volunteered.

Teaching Point

Patients who present with any overdose - make every attempt to get collateral

information.

Case 3

• 18 year old female

• Paracetamol overdose (50 x 500 mg tablets)

• Observations; T 37, P 90, BP 120/60, GCS 15

• Management?

Case 3• Assess and manage ABC's

• Toxic dose considered to be 150 mg/kg.

• Baseline bloods (FBC, EUC, LFT, Coag's, Paracetamol level)

• Repeat paracetamol at 4 hours

• Start NAC infusion.

Teaching Point

• NAC is the "antidote" for paracetmol toxicity

• In the setting of potentially hepatotoxic ingestion, start NAC early.

• Decision for ongoing therapy should be based on the 4 hour paracetamol level.

Case 4• 45 year old male

• Chronic alcohol dependence

• Alcohol intoxication, presents aggressive and agitated.

• Vital Signs; T 37, P 100, BP 110/60, RR 16, GCS 14/15

• Management?

Case 4• Assess and manage ABC's (Intravenous

fluids for HR and BP)

• Check BSL

• Give dextrose 25 g and thiamine 300 mg

• If no response, will need chemical restraint - what agent will you choose to sedate, and why?

Teaching Point• Alcohol and benzodiazepines are

sedative-hypnotic agents.

• Giving a BDZ to an agitated alcoholic will make the problem worse - use an antipsychotic.

• Always think of the possibility of intracranial pathology in an agitated alcoholic - low threshold for CT Brain.

Summary

• Management of poisoned patient is largely supportive

• Decontamination is rarely indicated (seek senior advice)

• In specific situations, an antidote may be of benefit.