Comprehensive Review of Nasogastric (NG) Tubes
Indications for NG Tube Placement
Fine bore NG tubes (5-8 French gauge) should be used for enteral feeding in adults when oral intake is absent or inadequate for 5-7 days, or within 24-48 hours in severely malnourished patients. 1
Primary Clinical Scenarios
Enteral Nutrition:
- Unconscious patients requiring nutritional support 1
- Swallowing disorders from neurological conditions (stroke, motor neurone disease, multiple sclerosis, Parkinson's disease) 2
- Head and neck cancer, maxillofacial trauma, or radiation stomatitis 2
- Mechanically ventilated patients requiring early feeding (within 24-48 hours) 2
- Post-surgical patients: within 1-2 days if severely malnourished, 3-5 days if moderately malnourished, or within 7 days if well-nourished 1
- Uncomplicated pancreatitis 1
Gastric Decompression:
- Bowel obstruction or severe ileus (requires large bore tubes, not fine bore feeding tubes) 3
- Patients undergoing rapid sequence intubation with high aspiration risk 2
- Gastric distention with estimated fluid volume >1.5 mL/kg 2
Contraindications
Absolute:
- Mechanical GI tract obstruction (unless for decompression) 2
- Active peritonitis 2
- Uncorrectable coagulopathy 2
- Bowel ischemia 2
Relative:
- Abnormal nasal anatomy 2
- Recent facial trauma or oronasal surgery 2
- Recent GI bleeding, especially from peptic ulcer with visible vessel or esophageal varices (delay 72 hours) 1, 2
- Hemodynamic instability 2
- Severe respiratory compromise 2
Tube Selection and Insertion Technique
Equipment Selection
Use fine bore 5-8 French gauge NG tubes for enteral feeding. 1 Large bore PVC tubes should be avoided as they irritate the nose and oesophagus and increase risks of gastric reflux and aspiration 1. For adults requiring decompression or administration of high viscosity feeds/drugs, larger bore tubes are necessary 1.
In stroke patients specifically, use 8 French tubes to minimize pressure sores 2.
Pre-Insertion Assessment
- Check INR for all patients before insertion 2
- Measure activated PTT only in patients receiving intravenous unfractionated heparin 2
- Platelet count and hematocrit are not routinely required 2
- Explain the procedure and obtain consent 2
Insertion Procedure
Position the patient with head flexed forward during insertion. 2 The tube should be lubricated thoroughly before insertion 2. NG tubes can be placed on the ward by experienced medical or nursing staff without x-rays to check position initially 1.
For standard NG tube placement, pass the tube through the nostril with the patient's head flexed and have them take sips of water to assist passage 2.
Position Verification: Critical Safety Step
Never rely solely on auscultation to verify tube position—it has only 79% sensitivity and 61% specificity and is dangerous. 2, 4
Mandatory Verification Methods
Every patient must undergo radiographic confirmation before initiating feeding to confirm proper gastric position. 1, 2, 4 Tubes can enter the lung, pleural cavity, or coil in the esophagus if position is not radiographically confirmed, which can be life-threatening 2.
For ongoing use, tube position must be checked using pH testing (aspirate should be pH <5.5) prior to every use. 1, 2 Auscultation and pH aspiration techniques can be inconclusive for nasojejunal tubes, which require x-ray confirmation 8-12 hours after placement 1.
Common Pitfall
Tubes positioned in the fundus are more prone to coiling or migrating back into the esophagus 2. If dysphagia worsens with the tube in place, suspect pharyngeal coiling and perform endoscopic evaluation or reinsert the tube 2.
Tube Securement and Maintenance
Proper securement is critical: 40-80% of NG tubes become dislodged without adequate securement. 1, 2
Securement Methods
- Nasal bridles reduce accidental removal from 36% to 10% compared to tape alone and should be considered for high-risk patients 2, 4
- For patients at high risk of skin breakdown, use a low-adherent film as a contact layer with full-adherent tape securing the tube to the film (avoiding direct skin contact) 2
Routine Maintenance
- Flush the tube with 40 mL of water after each medication administration or feeding 2
- Change dressing regularly and inspect the insertion site for irritation 2
- Long-term NG tubes should usually be changed every 4-6 weeks, swapping to the other nostril 1
- Monitor for signs of infection at the insertion site 2
Feeding Initiation and Management
Timing of Feed Initiation
Start feeding within 24-48 hours after proper tube placement confirmation. 2, 4 In critically ill patients, initiate feeding within 48 hours unless contraindicated by escalating vasopressor use or hemodynamic instability 2.
Withhold feeding in patients with uncontrolled shock, escalating vasopressor requirements, or hemodynamic instability until stabilization occurs 2.
Feed Prescription
Start at full-strength formula immediately once position is confirmed, without dilution or starter regimens, in patients with recent adequate nutritional intake. 2 Use 30 mL/kg/day of standard 1 kcal/mL feed as a reasonable starting point 2.
In severely malnourished patients, start at 50-70% of target calories and advance gradually over 3-5 days to prevent refeeding syndrome. 2, 4 Close monitoring of fluid, electrolytes (especially phosphate, potassium, magnesium), and glucose is crucial in the first 3-5 days 2, 4.
Administration Technique
- Position the patient at 30° or greater during feeding, and maintain this position for 30 minutes after bolus feeds to minimize aspiration risk 2
- Gastric feeding permits higher feeding rates, hypertonic feeds, and bolus administration compared to post-pyloric feeding 2
- For jejunal feeding, start at low rates (10 mL/h) and gradually increase to target rates 2
Monitoring for Complications
Monitor for signs of feeding intolerance including:
Special Considerations for Specific Populations
Post-Surgical Patients
Early enteral feeding after major GI surgery reduces infections and shortens length of stay. 1 Initiate within 1-2 days in severely malnourished, 3-5 days in moderately malnourished, and within 7 days in well-nourished patients 1, 2.
Early post-pyloric feeding is generally safe and effective in postoperative patients, even if there is apparent ileus 1.
Stroke Patients
- Assess for dysphagia before oral intake, as 40-78% of stroke patients experience dysphagia which can lead to aspiration pneumonia 2
- Early NG tube feeding (within 24 hours) may substantially decrease risk of death compared to delayed feeding 2, 3
- NG tubes do not necessarily impair swallowing therapy, which should start as early as possible 2
- For mechanically ventilated stroke patients requiring prolonged nutrition (>14 days), early PEG (within 1 week) is preferred over NG tube due to lower rates of ventilator-associated pneumonia 2
Critically Ill Patients
- Consider NG tube before rapid sequence intubation when aspiration risk is high 2
- Use clinical assessment and point-of-care ultrasound to determine need for decompression in patients with gastric distention 2
- Mechanically ventilated patients benefit from early gastric tube placement (within 24 hours) to reduce ventilator-associated pneumonia 3
Patients with Variceal Bleeding
Avoid NG tube insertion for three days after acute variceal bleeding, and only use fine bore tubes thereafter. 1
Unconscious Patients
Unconscious patients who must be nursed flat require nasojejunal tube placement rather than NG tubes to prevent aspiration. 1, 3
Complications and Management
Common Complications
Dislodgement (40-80% without proper securement):
Tube occlusion:
Sinusitis:
- Occurs with prolonged use beyond 3-4 weeks 2
- Consider transition to PEG if feeding needs exceed 4-6 weeks 1
Aspiration pneumonia:
- Especially in patients with impaired swallowing 2
- Prevented by proper positioning (30° elevation) and dysphagia assessment 2
Nasal and esophageal irritation:
Life-Threatening Complications
- Tubes entering the lung or pleural cavity if position not radiographically confirmed 2
- Refeeding syndrome in severely malnourished patients if not monitored closely 2, 4
Transition to Long-Term Access
Consider percutaneous gastrostomy (PEG) whenever patients are likely to require enteral feeding for more than 4-6 weeks. 1 Some evidence suggests considering PEG at 14 days post acute dysphagic stroke 1.
Advantages of PEG Over Long-Term NG
- Feeding without inconvenience, discomfort, and embarrassment of NG access 1
- Patients receive more of their prescribed feed (NG tubes "fall out" easily) 1
- Lower rates of ventilator-associated pneumonia in mechanically ventilated patients 2
PEG Indications
- Neurological disorders of swallowing (CVA, multiple sclerosis, motor neurone disease, Parkinson's disease, cerebral palsy) 1
- Cognitive impairment and depressed consciousness (head injury) 1
- Mechanical obstruction to swallowing (oropharyngeal or esophageal cancer, radiation enteropathy) 1
- Long-term partial failure of intestinal function requiring supplementary intake (short bowel, fistulae, cystic fibrosis) 1
Patient and Caregiver Education
Before discharge, ensure patients and caregivers can demonstrate competency in:
- Feed administration technique 2
- Equipment handling and setup 2
- Basic troubleshooting (tube or equipment failure) 2
- Recognition of complications requiring medical attention 2
Confirm that community caregivers are fully informed and ongoing prescriptions for feeds and equipment are in place 2.
Emergency Situations
Inadvertent removal of a recently placed percutaneous gastrostomy tube (less than 4 weeks post-insertion) is an emergency requiring immediate replacement to prevent peritonitis. 3 Replacement should be done endoscopically or radiologically through the same site in the first two weeks after initial placement 3.