Nasogastric tube

A nasogastric tube is a narrow bore tube passed into the stomach via the nose. It is used  eg for decompression of intestinal obstruction.A wide bore tube is used if drainage is needed; otherwise, a finer bore tube is used. Fine bore feeding tubes (gauge 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 percutaneous endoscopic gastrostomy (PEG) is associated with improved survival, better toleration by the patient and lower incidence of aspiration.

Contra-indications

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

High risk of aspiration

Gastric stasis

Gastro-oesophageal reflux

Upper gastrointestinal stricture

Nasal injuries

Base of skull fractures

Inserting a nasogastric tube

Explain the procedure and obtain consent

Provide a signal for the patient to stop the procedure

Sit the patient in a semi-upright position with the head supported with pillows and tilted neither backwards nor forwards

Examine the nostrils for deformity or obstructions to determine the best side for insertion

Measure the tubing from the bridge of the nose to the

earlobe, then from sternal  notch  to the xiphisternum

Mark the measured length with a marker or note the distance

Lubricate 2-4 inches of tube with lubricant (eg 2% Xylocaine

Pass the tube via either nostril, past the pharynx, into the oesophagus and then into 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 the tube slowly while advancing downwards.

Do not force stop immediately and withdraw the tube if patient becomes distressed, starts gasping or coughing, becomes cyanosed or if the tube coils in the mouth

Advance the tube until the mark is reached

Check the tube's position

Secure the tube with tape

Checking tube position

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

Put some air in to the nasogastrictube (get a help from an assistant)  during this time auscultate  over the abdomen  (if the NG tube in correct position we can hear the air follow sound  )

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.

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.

Securing and monitoring the tube

Nasogastric tubes should be taped securely at the nose to avoid displacement.

The 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

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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.