Module 2: Methods of GI Decontamination

2.1 Activated Charcoal: Mechanism, Administration, and Considerations

Activated charcoal is a foundational method of gastrointestinal (GI) decontamination. This simple yet highly effective agent is used widely in medical emergencies involving ingestion of toxins.

Activated charcoal functions due to its high adsorptive capacity. This means it can bind strongly to many different substances, preventing their absorption into systemic circulation. Its large surface area enhances this adsorptive property, creating more ‘binding spots’ for toxins.

Activated charcoal is typically prepared as a mixture of 1 gram of charcoal to 8 milliliters of liquid, which can be either water or soda. This mixture helps to enhance the palatability of activated charcoal. In some cases, flavoring agents can be added to further improve its taste. The administration can be done orally or via a nasogastric (NG) tube in intubated patients.

While activated charcoal is effective, it’s not suitable for all situations. It’s contraindicated in patients who cannot protect their airways, in cases of bowel obstruction, or situations where its use could interfere with endoscopic visualization. That said, the benefits of activated charcoal often outweigh the risks when appropriately used.

There are debates as to the exact window of effectiveness for activated charcoal. While some sources suggest it’s most effective within 1 hour of ingestion, others have proposed a window of up to 4 hours for specific toxins.

Activated charcoal is highly effective when administered within the proposed time window and in the absence of contraindications. However, it’s important to note that it does not bind well with alcohols, metals, acids/alkalis, hydrocarbons, or lithium.

Activated charcoal is recognized by the American Academy of Clinical Toxicology (AACT) as an effective method of GI decontamination. The AACT recommends that it be administered within 1 hour of ingestion.

Key Takeaways

1. Activated charcoal is highly adsorptive and can bind to many toxic substances.
2. It is most effective when administered within 1 hour of toxin ingestion.
3. Activated charcoal is contraindicated in cases of unprotected airways, bowel obstruction, or when it can interfere with endoscopic visualization.
4. The AACT recommends the use of activated charcoal for GI decontamination within the appropriate time window.

Procedures	Benefits	Risks
Activated Charcoal	High adsorptive capacity, simple administration	Unprotected airways, bowel obstruction, interference with endoscopy

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2.2 Gastric Lavage: Process, Risks, and Technique

Gastric lavage is a more invasive decontamination method. It involves the insertion of a large-bore orogastric tube into the stomach. Once the tube is in place, saline is instilled in aliquots to wash out the stomach contents.

For adult patients, a 36 to 40 French tube is typically used, while for pediatric patients, a smaller 24 to 28 French tube is used. The saline is instilled in 250mL aliquots, which are then aspirated and discarded.

The potential risks of gastric lavage include aspiration pneumonia, fluid and electrolyte imbalances, hypothermia, laceration of the GI tract, dysrhythmias, and fluid overload. These risks underscore the importance of proper patient selection – only those expected to develop severe toxicity or deterioration should undergo gastric lavage.

There’s ongoing debate regarding the use of gastric lavage. Some argue that the potential for complications outweighs the benefits, especially given the efficacy of less invasive methods like activated charcoal. However, in specific scenarios of severe poisoning, the benefits may outweigh the risks.

Gastric lavage can be effective in removing unabsorbed toxins from the stomach, but given its potential risks, it’s usually reserved for severe cases where the benefits outweigh the risks.

The AACT and the European Association of Poisons Centres and Clinical Toxicologists (EAPCCT) do not recommend gastric lavage in most poisoning situations due to its potential risks. They suggest considering it only in potentially life-threatening ingestions and only if performed within 1 hour of ingestion.

Key Takeaways

• Gastric lavage is a more invasive procedure that can remove unabsorbed toxins from the stomach.
• It carries significant risks, including aspiration pneumonia, fluid and electrolyte imbalances, and hypothermia.
• The AACT and EAPCCT do not generally recommend gastric lavage due to its potential complications.

Procedures	Benefits	Risks
Gastric Lavage	Effective removal of unabsorbed toxins	Aspiration pneumonia, fluid and electrolyte imbalances, hypothermia

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2.3 Whole Bowel Irrigation: Indications, Procedure, and Safety

Whole bowel irrigation (WBI) is another technique utilized for gastrointestinal (GI) decontamination. This process involves the administration of a polyethylene glycol electrolyte solution to cleanse the entire gastrointestinal tract.

The main indications for WBI include ingestion of sustained-release or enteric-coated drugs, ingestion of drugs not absorbed by activated charcoal (such as iron, lithium, or lead), and body packers or “stuffers” who have ingested illicit drugs wrapped in packets.

WBI is administered orally or via a nasogastric tube. A solution is continuously given until the rectal effluent is clear, typically requiring several hours. The rate of administration varies depending on the age of the patient. For adults, the usual rate is 1-2 liters per hour, while for children, it’s 500 mL/hour for those aged 1-6, and 1000 mL/hour for those aged 6-12.

Safety considerations are crucial when determining the use of WBI. It should be avoided in patients with bowel obstruction, perforation, or ileus, and in those with hemodynamic instability or compromised airways. Side effects can include abdominal cramping, nausea, vomiting, and bloating.

Like other GI decontamination methods, the timing of administration is critical. WBI is most effective when initiated within 4 hours of ingestion. However, due to its ability to clear the entire GI tract, it can be beneficial even later in certain cases, such as ingestions of sustained-release medications or in body packers.

The American Academy of Clinical Toxicology (AACT) and the European Association of Poisons Centres and Clinical Toxicologists (EAPCCT) maintain cautious stances on WBI. They recommend its use only in selected cases where benefits are likely to exceed risks.

Key Takeaways

• Whole bowel irrigation (WBI) is a method of GI decontamination that can clear the entire GI tract.
• It’s most effective when initiated within 4 hours of ingestion but can be beneficial later in certain cases.
• WBI is contraindicated in cases of bowel obstruction, perforation, ileus, hemodynamic instability, or compromised airways.
• The AACT and EAPCCT recommend the use of WBI only in selected cases where benefits are likely to exceed risks.

Procedures	Benefits	Risks
Whole Bowel Irrigation	Clears the entire GI tract, effective for certain toxins	Bowel obstruction, perforation, ileus, hemodynamic instability, compromised airways

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2.4 Summary of GI Decontamination Methods

In summary, activated charcoal, gastric lavage, and whole bowel irrigation are different methods of GI decontamination, each with its unique considerations.

Activated charcoal is often the first-line approach due to its simplicity, effectiveness, and lower risk profile. Gastric lavage and whole bowel irrigation are more invasive procedures reserved for specific scenarios when their benefits outweigh their potential risks. It’s important to note that patient-specific factors, the nature of the ingested substance, and the time elapsed since ingestion all play crucial roles in deciding which method to use.

Clinical guidelines from the AACT and EAPCCT provide valuable direction in these situations, emphasizing a judicious approach to GI decontamination where the potential benefits must be weighed against the risks.