Gut decontamination plays a crucial role in reducing toxin absorption after ingestion of poisonous substances. While not required in all poisoning cases, timely and appropriate use of decontamination methods can significantly limit systemic toxicity. Choosing the correct technique depends on the type of poison, time since exposure, and the clinical condition of the patient.
Goals of Gut Decontamination
The primary aim of gut decontamination is to prevent further absorption of the ingested toxin. It is most effective when initiated early, ideally within one to two hours of ingestion. Decontamination strategies are used selectively, based on risk–benefit assessment, to avoid unnecessary complications.
1. Activated Charcoal
Activated charcoal is the most commonly used method for gastrointestinal decontamination. Its large surface area allows it to adsorb a wide range of toxins, preventing their absorption into systemic circulation.
Indications
- Ingestion within the past 1–2 hours
- Substances known to bind to charcoal (e.g., paracetamol, salicylates, TCA, carbamazepine)
- Patients with intact airway reflexes
Contraindications
- Unprotected airway or risk of aspiration
- Ingestion of corrosives (acids, alkalis)
- Hydrocarbon ingestion
- Poor intestinal motility or obstruction
Administration
The usual dose of activated charcoal is 1 g/kg body weight, administered orally or through a nasogastric tube. Multiple-dose activated charcoal may enhance elimination of toxins such as phenobarbitone, dapsone, carbamazepine, and theophylline.
2. Gastric Lavage
Gastric lavage, also known as stomach wash, is a mechanical method to remove ingested toxins from the stomach. Its use is now highly restricted and reserved for life-threatening poisonings where the patient presents very early.
Indications
- Life-threatening ingestion within one hour
- Substances with significant morbidity if absorbed
- Cases where activated charcoal is insufficient or contraindicated
Procedure Highlights
- Use a large-bore, flexible, orogastric tube
- Position the patient in left lateral decubitus
- Instill and withdraw warm saline repeatedly
- Continue until clear fluid is obtained
Risks and Complications
- Aspiration pneumonia
- Mechanical injury to throat or esophagus
- Electrolyte imbalance if excessive lavage is done
3. Induced Emesis
Inducing vomiting was previously common but is now rarely recommended. Syrup of ipecac was once used, but due to limited effectiveness and significant risk, it is no longer advised in modern toxicology practice.
Reasons for Avoidance
- Delayed onset reduces effectiveness
- Risk of aspiration
- Potential for prolonged vomiting and dehydration
- Not effective for many modern toxins
4. Whole Bowel Irrigation
Whole bowel irrigation (WBI) involves flushing the gastrointestinal tract using large volumes of polyethylene glycol electrolyte solution. It is particularly useful for substances not adsorbed by activated charcoal.
Indications
- Iron overdose
- Lithium poisoning
- Body packers or body stuffers
- Extended-release drug formulations
Procedure
The patient receives polyethylene glycol solution orally or via nasogastric tube until rectal effluent becomes clear. Careful monitoring of fluid balance is required.
5. Cathartics
Cathartics such as sorbitol or magnesium sulfate may enhance gastrointestinal transit but are generally not recommended as standalone therapy. They may occasionally be used alongside activated charcoal but carry risks of dehydration and electrolyte disturbances.
Limitations of Gut Decontamination
Some toxins are absorbed too rapidly for effective decontamination. Others, such as hydrocarbons, corrosives, alcohols, and heavy metals, may not benefit from gastrointestinal methods. Not all patients require decontamination; clinical judgment is essential.
Detailed Notes:
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PATH: PHARMD/ PHARMD NOTES/ PHARMD FOURTH YEAR NOTES/ CLINICAL TOXICOLOGY/ GUT DECONTAMINATION.