What GFC (Gastrostomy Feeding Catheter) Tubes Contain
Gastrostomy feeding tubes are hollow catheter devices made of biocompatible materials (polyurethane or silicone rubber) that contain an internal lumen for feed delivery, a retention mechanism (balloon or bumper), and external ports for feeding and medication administration. 1
Physical Components and Materials
Tube Construction
- Modern gastrostomy tubes are manufactured from polyurethane or silicone rubber, which are well-tolerated materials that minimize tissue irritation and allow for long-term use (>10 years with proper care). 1, 2
- The tubes contain a hollow internal lumen through which enteral nutrition formulas, medications, and fluids are delivered. 3
- Tube sizes typically range from 5-8 French gauge for fine bore tubes, though gastrostomy tubes for venting purposes require at least 20 French gauge for effective drainage. 1, 4
Retention Mechanisms
- Gastrostomy tubes are held in place by either a balloon (similar to Foley catheters) or a deforming/rigid fixation device at the internal gastric end. 1
- Tubes with balloon retention can be removed with gentle traction after balloon deflation, while those with rigid fixation devices typically require endoscopic removal. 1
- Foley urinary catheters can serve as temporary gastrostomy tubes to maintain tract patency when replacement tubes are unavailable, though they carry a 42.6% complication rate including balloon rupture, blockage, and migration. 5
External Components
- External ports allow for feed administration, medication delivery, and in some cases, gastric aspiration through a secondary shorter lumen. 1
- The tubes include external fixation devices to secure them against the abdominal wall and prevent migration. 1
What Flows Through the Tubes
Enteral Nutrition Formulas
- Most patients tolerate high-energy polymeric feeds (1.5-2 kcal/mL), which contain intact proteins, carbohydrates, and fats requiring normal digestive function. 1
- Elemental or semi-elemental feeds may be used when polymeric feeds are not tolerated, particularly in patients with malabsorption. 1
- All feeds require pancreatic enzyme replacement therapy (PERT) in patients with pancreatic insufficiency, with dosing calibrated at the beginning and end of feeds. 1
Medications
- Liquid medications (elixirs and suspensions) are strongly preferred for gastrostomy administration to prevent tube occlusion. 3
- Solid dosage forms may be crushed or opened only after determining suitability for manipulation, as some medications lose efficacy or cause adverse effects when altered. 3
- Each medication must be flushed with water before and after administration to prevent drug-nutrient interactions and tube blockage. 3
Fluids
- Water for hydration is delivered at 30-35 mL/kg body weight, with adjustments for excessive losses from drains or fistulae. 6
- Tubes must be flushed with water before and after each use to maintain patency and prevent occlusion. 3
Critical Monitoring Requirements
- Close monitoring of fluid, glucose, sodium, potassium, magnesium, calcium, and phosphate is essential in the first days after initiating feeds or when using gastric decompression. 6
- Patients require monitoring for glucose intolerance, as continuous feeding may necessitate small insulin doses for management. 1
- Tube function, peristomal site integrity, and signs of infection or leakage must be regularly assessed. 4