Clinical Toxicology Management

Clinical Toxicology - Initial Evaluation & Management

• Clinical toxicology focuses on the effects of drugs and chemicals on humans (and animals). It often involves drug overdoses and poisonings, identifying the substance and its amount in the body.
• It works alongside other sciences like biochemistry, pharmacology, and pathology.
• Clinical toxicology examines the adverse effects of various agents, including drugs and chemicals.
• All poisoned patients should be managed as if they have a life-threatening condition, even if they appear normal. The initial approach should be uniform, irrespective of the ingested toxin. This is termed "routine poison management".

Outline

• Clinical Toxicology
• Approaches and Initial Evaluation
• Management
• Definitive care with poisoning
• Supportive Care and Monitoring

Approach to Poisoned Patients

• All poisoned patients must be managed as having a potentially life-threatening condition, regardless of outward appearance.
• The initial approach remains essentially the same, no matter what toxin was ingested.

Common Poisoning Sources

• Poisoning can result from various substances, ranging from household cleaners to pesticides.
• Prescription and over-the-counter medications account for nearly half of poisoning exposures.

Important Strategies

• Treat the patient promptly, not the poison.
• Supportive therapy is essential: maintain respiration and circulation.
• Monitor intoxication by measuring and recording vital signs and reflexes.
• Treatment goal 1: keep poison levels low by preventing absorption and increasing elimination.
• Treatment goal 2: counteract toxic effects at the affected site (if possible).

Initial Evaluation (ABCDEs)

Airway

• Maintain a patent airway.
• Remove any obstructions.
• Loss of airway reflexes is a significant cause of poisoning death in many cases. This can lead to obstruction caused by flaccid tongue or aspirated gastric contents.

Breathing

• Evaluate respiratory rate and oxygen saturation.
• If no oxygen monitor is available, consider supplemental oxygen if respiratory rate is elevated.

Circulation

• Promptly assess vital signs and hydration status.
• Check blood pressure, pulse rate, and rhythm.
• Start continuous ECG monitoring
• Secure venous access.
• Draw blood for routine studies.
• Administer normal saline (or similar isotonic solution) if the patient is hypotensive.

Disability (Neurological)

• Assess level of consciousness.
• A decreased level of consciousness is a common severe complication of drug overdose/poisoning.
• In seizure cases, check blood sugar levels. If less than 72 mg/dL, an IV of 50mL of 50% dextrose should be administered.
• Treat toxic seizures with IV benzodiazepines; refractory seizures can use barbiturates.

Exposure (Temperature)

• Assess temperature.
• Consider toxic syndromes associated with hyperthermia.
• Some drugs at toxic levels can cause a significantly elevated body temperature.

Definitive Care with Poisoning

• Identify the poison.
• Gather an accurate history from alternative sources (family, friends, pharmacist, scene).
• Determine the time and amount of ingestion.

Supportive Care & Monitoring

• Acute poisoning is a dynamic condition; patients' conditions can change over time.
• Repeated examinations and ongoing clinical assessment/management are essential

Physical Examination

• Vital signs (pulse, respiration, blood pressure, temperature, oxygen saturation).
• Neurological exam (including pupil size, Glasgow Coma Scale, mental state, reflexes, clonus, focal signs).
• Skin condition (color, sweating).
• Moisture in the mouth/salivation; bowel sounds; urinary retention.
• Evidence of trauma (injuries).

Risk Assessment

• Early, accurate risk assessment is vital to manage acutely poisoned patients.
• Assessment predicts likely clinical course, identifies potential complications, and guides management plans.
• 5 steps of risk assessment include:
  • Agent identification (toxicity potential).
  • Dose calculation (mg/kg body weight).
  • Time since ingestion.
  • Clinical features and progress.
  • Patient factors (weight, comorbidities).

Investigations

• Blood sugar levels
• ECG monitoring (rate and rhythm).

Management

• The goal in poisoning management is to:
• Prevent further poison absorption.
• Increase poison elimination.
• Administer antidote (if indicated).

Prevention of Further Poison Absorption

• Dermal exposure:
  • Remove all clothing.
  • Wash skin thoroughly with soap and water for at least 30 minutes.
• Eye exposure:
  • Flush the eyes with running water or saline for 20 minutes.
  • Remove solid corrosives with forceps.
• Gastrointestinal (GI) tract exposure:
  • Emesis induction (if appropriate, and not contraindicated).
  • Gastric lavage (if appropriate).
  • Activated charcoal (if appropriate and not contraindicated).
  • Cathartics.
  • Whole bowel irrigation (if appropriate).

Induction of Emesis (Vomiting Induction)

• Ipecac syrup can induce vomiting but should only be given within 30 minutes of ingestion.
• Regular use of ipecac syrup as a home poison treatment is now discouraged.
• Contraindications for ipecac include seizures, corrosive ingestions, hydrocarbon exposures, coma, and age less than 6 months.

Gastric Lavage

• A method to remove ingested poisons from the stomach.
• It is most effective within 4-6 hours of ingestion.
• An assistant with a suction device is needed.

Activated Charcoal

• Absorbs toxins, preventing their absorption.
• 1 gram per kilogram (1g/kg) adult dose is commonly used.
• Must be administered within one hour of ingestion.
• Not appropriate for patients at risk of airway compromise, or in cases where an oral antidote was already given, cases of seizures, coma or corrosive ingestions.

Cathartics (Laxatives)

• Enhance the passage of materials through the gastrointestinal tract, reducing contact time between the toxin and digestive system cells.
• Types include osmotic (like magnesium sulfate) and irritant (like castor oil) cathartics.
• Contraindications include gastrointestinal (GI) bleeding, recent bowel surgery, or intestinal blockages.

Whole Bowel Irrigation (WBI)

• Used for substances that are poorly absorbed.
• Uses polyethylene glycol electrolyte solutions.
• Used in situations where massive quantities of drugs, sustained-release drugs, or enteric-coated preparations have been swallowed, or in the removal of illegal drug packets (body packers).

Antidotes

• Substances used to counteract the harmful effects of a poison.
• Categories include:
  • Physical: Interfere with the poison through physical means (e.g., activated charcoal).
  • Chemical: Interact chemically with the poison (e.g., oxidizing, reducing, precipitating agents).
  • Physiological: Antagonism (e.g., competing for receptor sites) or chelation (binding to form an easily excreted complex).

Enhancement of Poison Excretion

• Forced diuresis: manipulates urine pH to increase the rate of toxin excretion, e. g. mannitol, fluid diuresis
• Dialysis: employs semipermeable membranes to remove toxins when renal function is hindered, examples include peritoneal and hemodialysis
• Hemoperfusion: using equipment similar to hemodialysis, where blood is pumped through a column with adsorbent material (charcoal or resin)