Management of ingested poisons

Ingestion is the most common route of poisoning worldwide. Toxic exposure should be suspected in any patient presenting with unexplained altered mental status, metabolic derangement, or multi-system symptoms, regardless of a reported history of ingestion.

Ingested toxins are suspected in any patient with signs and symptoms irrespective of reported dose ingested.

Poisoning severity depends on

• Type of toxin (drug, pesticide, hydrocarbon, plant, heavy metal)

• Dose and concentration

• Time since ingestion

• Co-ingestion (alcohol or multiple drugs)

• Patient age, comorbidities, and nutritional status

Risk factors

Patient-related

• Children <5 years (exploratory ingestion)

• Adolescents (intentional self-harm)

• Psychiatric illness

• Substance abuse

• Elderly with polypharmacy

• Chronic kidney or liver disease

Environmental

• Improper storage of chemicals

• Use of unlabeled containers

• Agricultural pesticides in households

• Traditional/herbal medicines

Drug-related

• Narrow therapeutic index drugs

• Sustained-release formulations

• Polypharmacy interactions

Clinical presentations

General clinical features

• Nausea

• Vomiting

• Drowsiness

• Blurred vision

• Dizziness

Central nervous system toxicity

• Altered level of consciousness

• Acute confusion

• Convulsions

• Coma

Renal toxicity

• Acute kidney injury/failure

• Papillary necrosis

• Oliguria or anuria

Metabolic derangement

• Metabolic acidosis

• Respiratory acidosis

• Hypoglycemia

Allergic reactions

• Urticaria

• Angioedema

• Anaphylaxis

Hematological toxicity

• Aplastic anemia

• Agranulocytosis

Diagnostic criteria

Diagnosis is clinical and laboratory supportive:

• History or suspicion of ingestion

• Compatible toxidrome

• Laboratory abnormalities

• Exclusion of other causes

Recognition of toxidromes

Investigations

Initial emergency tests (all patients)

• Blood glucose (immediate bedside)

• Arterial blood gas

• Serum electrolytes

• Renal function tests

• Liver function tests

• Complete blood count

• Urinalysis

Toxicology investigations

• Serum drug levels (paracetamol, salicylate, lithium)

• Blood alcohol level

• Toxicology screen (if available)

Additional tests

• ECG (cardiotoxic drugs)

• Serum osmolality and osmolar gap

• Lactate

• Coagulation profile

• Pregnancy test in females

Imaging

• Chest X-ray (aspiration)

• Abdominal X-ray (metal ingestion, drug packets)

• CT brain if persistent coma

Treatment

Non-pharmacological management

Initial stabilization (always first)

Airway – Breathing – Circulation (ABC):

• Secure airway

• Provide oxygen

• IV access and fluids

• Monitor ECG

• Correct hypoglycemia immediately

• Control seizures

Gastrointestinal decontamination

Gastrointestinal decontamination is the practice of removing an ingested toxin from the gastrointestinal tract to decrease absorption. It includes gastric evacuation (forced emesis or gastric lavage), intra-gastric binding (single or multidose activated charcoal), or speeding transit of toxins (whole bowel irrigation or cathartics).

It is most beneficial within 1–2 hours of ingestion.

Gastric lavage

May be considered in selected cases.

Procedure (general care)

• Keep patient under observation for 4–24 hours depending on toxin

• Position: left lateral, head down

• Insert large nasogastric tube

• Use warm 0.9% saline repeatedly until clear return

• Suction ready; intubate if aspiration risk

Contraindications

• Unprotected airway in unconscious patient

• Ingestion of corrosives or petroleum products (e.g. kerosene)

• Bowel obstruction

• Bowel perforation

• Gastrointestinal bleeding

Important notes

• Forced vomiting is not recommended and is highly discouraged.

• Gastric lavage only in life-threatening poisoning within 30 minutes to 1 hour of ingestion, when no safer alternative is available.

• Whole bowel irrigation may be considered in selected cases; routine cathartics are not recommended.

• Treatment works best within 1 hour of the poisoning.

• For kerosene, petrol or petrol-based products (including most pesticide solvents), or mouth and throat burns (bleach, toilet cleaner, battery acid), do not make the patient vomit; give water by mouth.

• Never use salt as an emetic: it can be fatal.

• If charcoal is not available, induce vomiting only in a conscious patient (by rubbing the back of the throat with a spatula or spoon handle).

Pharmacological treatment

Activated charcoal (single dose)

• Within 1 hour of ingestion of adsorbable toxins

• Given orally or via NG tube

Dose

• Children <1 year: 1 g/kg

• Children 1–12 years: 25–50 g

• Adolescents/adults: 25–100 g

Administration

• Mix in 8–10× water

• Give orally or NG tube

• If intolerance occurs, divide dose

Contraindications

• Corrosives

• Hydrocarbons

• Ileus or obstruction

• Unprotected airway

Multiple-dose activated charcoal (indicated toxins)

• Carbamazepine

• Dapsone

• Digoxin

• Paraquat

• Phenobarbitone

• Quinine

• Slow-release theophylline

• Amanita phalloides

• A: Activated charcoal (PO or NG tube), single dose, within 1 hour of ingestion, only if the airway is protected: children below 1 year 1 g/kg; children 1–12 years 25–50 g; adolescents and adults 25–100 g.

• Mix the charcoal in 8–10 times its amount of water (for example 5 g in 40 ml); give it all at once, or divide the dose if the child cannot tolerate it.

• Multiple doses of activated charcoal are indicated for carbamazepine, dapsone, digoxin, paraquat, phenobarbitone, quinine, slow-release preparations such as theophylline, and Amanita phalloides mushrooms, and may be considered in life-threatening overdose of other drugs such as tricyclic antidepressants.

• Do not give activated charcoal for corrosives or petroleum products (kerosene, petrol).

Fluids

• Compound sodium lactate or 0.9% sodium chloride (IV) 30 mL/kg (up to 2 liters over 24 hours) if shock is present

Specific antidotes

Supportive therapy

• IV fluids

• Electrolyte correction

• Benzodiazepines for seizures

• Vasopressors for shock

• Mechanical ventilation if needed

• Hemodialysis for dialyzable toxins

Prevention

Do’s

• Store medicines safely

• Use child-resistant containers

• Keep products in original packaging

• Read labels carefully

Don’ts

• Do not transfer chemicals into drink bottles

• Do not leave containers open

• Do not remove labels

• Do not refer to medicines as sweets

• Avoid taking medicine in front of small children

Referral

Consider transfer to higher-level care if:

• Unconscious or deteriorating level of consciousness

• Burns to the mouth and throat

• Severe respiratory distress

• Cyanosis

• Heart failure

• Call the National Poison Control Centre on the toll-free number 0800 112031 for advice.