General Approach and Management of Poisoned Patients Module 4 – Gastrointestinal Decontamination

Lesson 4 of 10

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Module 4 – Gastrointestinal Decontamination

Learning Objectives

Understand current evidence-based guidelines on gastric lavage
Recognize appropriate uses and dosing of activated charcoal
Determine when whole bowel irrigation is indicated
Appreciate risks and contraindications of GI decontamination methods

Gastric Lavage

– Gastric lavage involves passage of a large-bore orogastric tube and administration of small aliquots of tap water or saline.

– It is intended to remove toxins before absorption by mechanically emptying stomach contents.

– Lavage is now very rarely indicated given lack of demonstrated efficacy and risk of complications.

– Consider ONLY in potentially lethal ingestion when ALL of the following criteria are met:

Ingestion of life-threatening amount of toxin
Ingestion within 60 minutes (perhaps up to 2 hours for sustained-release agents)
Patient has protected airway via intubation
Contraindications are absent

– Never perform in a patient with unsecured airway – high risk of aspiration.

– Avoid in ingestion of corrosives or hydrocarbons – increases risk of GI injury.

Activated Charcoal

– Administer activated charcoal (AC) to adsorb toxins in GI tract and prevent absorption.

– Give AC as a 50-100 g single dose in adults, 1 g/kg in children up to 25 g.

– Mix AC suspension with water or soda – does NOT need to be administered via NG tube.

– Within 1 hour of ingestion, AC significantly reduces drug bioavailability. Still somewhat effective 1-2 hours after ingestion.

– Ensure proper airway protection before giving AC in patients with depressed mental status.

Special indications for AC:

– Life-threatening overdose ingestions

– Sustained-release or extended-release drug formulations

– Substances that delay gastric emptying like anticholinergics or opioids

– Severely toxic substances even late after ingestion

Contraindications:

– Caustic or corrosive ingestions (increases risk of perforation)

– Hydrocarbon ingestion (increases risk of aspiration)

– Bowel obstruction or ileus – Inability to protect airway in obtunded patient

Whole Bowel Irrigation

– Whole bowel irrigation (WBI) uses large volumes of polyethylene glycol solution to flush out GI tract.

– Indicated for potentially toxic ingestions of iron, lithium, lead, zinc, or potassium.

– Useful for overdose of sustained-release or enteric coated medications.

– Consider for “body packers” to accelerate transit of drug packets.

– Administer PEG solution at 500 mL/hr in children, 1-2 L/hr in adults.

– Continue until rectal effluent is clear – usually requires at least 3-6 liters total volume.

– Patients must be able to cooperate and swallow the large fluid volumes.

– Avoid in patients with bowel obstruction, perforation, or hemodynamic instability.

– Obtain abdominal x-rays to monitor progress of radiopaque markers or drug packets.

Multiple-Dose Activated Charcoal

– Administer multiple doses of AC to enhance elimination of toxins post-absorption.

– Binds drugs undergoing enterohepatic recirculation or luminal diffusion in the gut.

– Dose is 12.5-50 g AC every 2-4 hours; avoid sorbitol as cathartic.

– Continue for 12-24 hours after acute overdose depending on half-life of toxin.

– Shown to increase clearance of some drugs like carbamazepine, phenytoin, phenobarbital.

– Requires a protected airway and GI motility – avoid with ileus, obstruction, perforation.

– Not demonstrated to improve clinical outcomes, therefore not universally recommended.

In summary, judicious use of GI decontamination with proper patient selection optimizes the risk/benefit ratio. Gastric lavage is rarely indicated while AC remains commonly used though with important caveats.

General Approach and Management of Poisoned Patients

Quizzes

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