Nasogastric (Ryles) Tubes

There are separate articles on Enteral feeding, Nutritional support in primary care and Nutritional support in hospital.

A nasogastric tube is a narrow bore tube passed into the stomach via the nose. It is used for short or medium term nutritional support, and also for aspiration of stomach contents, e.g. for decompression of intestinal obstruction.¹ A wide bore tube is used if drainage is needed, otherwise, a finer bore tube is used. Fine-bore feeding tubes (guage less than 9) cause less discomfort and less risk of rhinitis, pharyngitis or oesophageal erosion.

The use of a nasogastric tube is suitable for enteral feeding for up to six weeks. Polyurethane or silicone feeding tubes are unaffected by gastric acid and can therefore remain in the stomach for a longer period than PVC tubes, which can only be used for up to 2 weeks. For long-term enteral feeding, the use of PEG (percutaneous endoscopic gastrostomy) is associated with improved survival, better toleration by the patient and lower incidence of aspiration.²

Enteral feeds can be given as:

• Bolus: by gravity, very simple requiring minimal equipment but increases risk of GI symptoms
• Intermittently: by gravity or pump, gives time free of feeding but increases risk of GI symptoms
• Continuously: by pump system, reduces rate of GI symptoms but patient connected to system most of the time and may limit mobility.

The nasogastric feeding route is not suitable for all patients, including those with:³

• High risk of aspiration
• Gastric stasis
• Gastro-oesophageal reflux
• Upper gastrointestinal stricture
• Nasal injuries
• Base of skull fractures

• Explain procedure and obtain consent
• Provide signal for patient to stop procedure
• Sit patient in semi-upright position with head supported with pillows tilted neither backwards or forwards
• Examine nostrils for deformity or obstructions to determine best side for insertion
• Measure tubing from bridge of nose to earlobe, then to the point halfway between the lower end of the sternum and the navel
• Mark measured length with a marker or note the distance
• Lubricate 2-4 inches of tube with lubricant (e.g. 2% Xylocaine).
• Pass tube via either nostril, past the pharynx, into the oesophagus and then the stomach.
• Instruct the patient to swallow and advance the tube as the patient swallows (sipping a glass of water helps).
• If resistance is met, rotate tube slowly while advancing downwards. Do not force.
• Stop immediately and withdraw tube if patient becomes distressed, starts gasping or coughing, becomes cyanosed or if tube coils in mouth
• Advance tube until mark is reached
• Check tube position (see below)
• Secure tube with tape

It is essential to confirm position of the tube in stomach by one of the following:⁵

• Testing pH of aspirate: gastric placement is indicated by a pH of less than 4, but may increase to between pH 4-6 if the patient is receiving acid-inhibiting drugs. The use of blue litmus paper to check the acidity of aspirate is insufficiently sensitive to distinguish between levels of acidity.⁶
• X-rays: will only confirm position at the time the x-ray is carried out. The tube may have moved by the time the patient has returned to the ward. In the absence of a positive aspirate test, where pH readings are more than 5.5, or in a patient who is unconscious or on a ventilator, an X-ray must be obtained to confirm the initial position of the nasogastric tube.

The old test of introducing a small quantity of air into stomach and check for bubbling sound over epigastrium is not recommended as it is unreliable and can give false reassurance.

• Nasogastric tubes should be taped securely at the nose to avoid displacement.
• Nasogastric tube should be flushed regularly to prevent the build up of feed and medication leading to occlusion.
• The position of the tube should be monitored by recording the length of the tube at the point of exit from the nostril, regularly checking the pH of the aspirate, checking the nasal fixation tapes daily and checking for signs of respiratory discomfort or regurgitation.
• The tube position must be checked:
  • On initial placement.
  • At least once daily during continuous feeds, or before the administration of feed following a break or if bolus feeding.
  • Before the administration of drugs if the tube is not used for any other purpose.
  • After episodes of coughing, retching or vomiting.
  • After oropharyngeal suction.
  • Any suspicion of a change in length of the visible part of the tube.
  • Any discomfort or reflux of feed into the throat.
  • Any signs of respiratory distress.
  • If the patient is transferred from one clinical area to another.

• Most medication is not licensed for administration through a nasogastric tube
• A pharmacist should be consulted for advice as to the most appropriate preparation for administration through an enteral tube.