What is the recommended feeding regimen for a patient receiving 3-hourly bolus nasogastric (NG) tube feedings?

3-Hourly Bolus Nasogastric Tube Feeding Regimen

For patients receiving 3-hourly bolus NG tube feedings, administer 200-400 mL of full-strength formula per bolus (divided from total daily volume into 6-8 feeds throughout the day), delivered over 15-60 minutes using a syringe with or without plunger, after confirming tube position and elevating the head of bed to at least 30 degrees. 1

Pre-Feeding Requirements

Before initiating any 3-hourly bolus feeding regimen, you must:

• Verify correct tube placement using pH testing (aspirate should be pH <5.5) prior to every use, or confirm initial placement radiographically 2
• Position the patient with head of bed elevated to at least 30 degrees during feeding and maintain this position for 30 minutes after each bolus to minimize aspiration risk 1
• Assess for refeeding risk in malnourished patients, as metabolic complications can be life-threatening 2

Bolus Feeding Protocol

Volume and Frequency

• Divide total daily feed volume into 6-8 boluses administered every 3 hours (e.g., if target is 1800 mL/day, give 225-300 mL per bolus) 1
• Each bolus should be 200-400 mL administered over 15-60 minutes depending on patient tolerance 1
• Use a 50 mL syringe with or without plunger for administration 1

Formula Selection and Strength

• Start with full-strength standard 1 kcal/mL polymeric formula immediately once position is confirmed—there is no evidence supporting dilution or starter regimens in patients with recent adequate nutritional intake 1, 2
• Use approximately 30 mL/kg/day of standard formula as a reasonable starting point, though this may be excessive in severely malnourished or metabolically unstable patients 1

Critical Safety Measures

• Flush the tube with 30-50 mL of water before and after each bolus feed to prevent tube obstruction 1, 3
• Check gastric residuals every 4 hours—if aspirates exceed 200 mL, review the feeding regimen as this indicates delayed gastric emptying 1
• Monitor for signs of feeding intolerance including nausea, vomiting, abdominal distension, or diarrhea 2

Advantages of 3-Hourly Bolus Feeding

Bolus feeding into the stomach is considered more physiological than continuous feeding 1. Key benefits include:

• No requirement for feeding pump, reducing equipment costs and complexity 1
• Greater patient mobility and independence between feeds 1
• No evidence that bolus feeding predisposes to diarrhea, bloating, or aspiration compared to continuous feeding 1
• May be more beneficial for muscle protein synthesis and gastrointestinal hormone secretion compared to continuous feeding 4

When Bolus Feeding is Appropriate

• Gastric feeding only—bolus administration requires the tube to terminate in the stomach, not jejunum 1, 2
• Patient must be medically stable with stable hemodynamics 2
• Patient should be able to tolerate the volume and rate 1
• Most appropriate for medically stable patients with respect to cost, convenience, and patient mobility 4

Common Pitfalls and How to Avoid Them

Aspiration Risk

• Never feed patients in supine position—gastro-oesophageal reflux occurs in up to 30% of patients with tracheostomies and 12.5% of neurological patients when fed supine 1
• Aspiration may occur with no obvious vomiting or coughing, and pneumonia can develop silently 1
• Maintain 30-degree elevation during and for 30 minutes after each bolus 1

Tube Blockage

• Flush with 30-50 mL water before and after every feed—tubes block easily if not flushed properly 1
• Avoid administering crushed tablets, hyperosmolar drugs, potassium, iron supplements, or sucralfate through the tube 1
• Use liquid medications (elixirs or suspensions) rather than syrups when possible 1

Tube Dislodgement

• Secure tube properly—dislodgement occurs in 40-80% of NG tubes without proper securement 2
• Consider nasal bridles for high-risk patients (reduces dislodgement from 36% to 10%) 2
• Change long-term NG tubes every 4-6 weeks, swapping to the other nostril 1

Monitoring Requirements

During the first few days of feeding:

• Check urine glucose and electrolytes every 6 hours until stable 3
• Monitor fluid intake/output every 8 hours and daily weights 3
• Measure serum electrolytes, BUN, and glucose daily until stable, with particular attention to sodium, potassium, magnesium, calcium, and phosphate to prevent refeeding syndrome 1, 3
• Assess for signs of infection at the insertion site 2

Special Considerations for Severely Malnourished Patients

In severely malnourished patients at high risk for refeeding syndrome:

• Start at 50-70% of target volume and advance gradually over 3-5 days 2
• Close monitoring of electrolytes is essential during the first few days 1, 2
• Consider more frequent (every 2-3 hours) smaller boluses initially to improve tolerance 2

When to Consider Alternative Methods

• If feeding needs exceed 4 weeks, consider percutaneous endoscopic gastrostomy (PEG) rather than continuing NG tube 1, 2
• If patient cannot tolerate bolus volumes or experiences persistent high gastric residuals, switch to continuous pump feeding which reduces gastric pooling 1
• For jejunal feeding, bolus administration is contraindicated—use continuous pump feeding starting at 10 mL/h 1