Nasogastric tube

Discuss the steps in placing a NG tube?

  • Explain the procedure to the patient.
  • Mark the tube at a distance equal to that from the xiphisternum to the nose via the earlobe (50–60 cm). Fine bore 5-8 French NG tubes are used for feeding.
  • Lubricate the tube externally with gel/water and internally with water if a guidewire is present. Check the guidewire moves freely.
  • Check nasal patency by ‘‘sniff’’ with each nostril occluded in turn. The clearer nostril can be sprayed with lignocaine to minimise discomfort.
  • Sit the patient upright with the head level. Slide the tube gently backwards along the floor of the clearer nostril until visible at the back of the pharynx (10–15 cm).
  • If the patient is cooperative, ask them to take a mouthful of water and then advance the tube 5–10 cm as they swallow.
  • Repeat the water swallow/advance until the preset mark on the tube reaches the nostril.
  • Withdraw the tube at any stage if the patient is distressed, coughing, or cyanosed.
  • If there is difficulty passing the tube, ask the patients to tilt their head forwards or turn it to one side.
  • Once in place, remove any guidewire and secure carefully.
  • Check position of the tube before use (this does not usually require an x ray).

If the tube aspirate has a pH < 5, it confirms proper placement of NG tube. X-ray confirmation is only needed if there is any doubt over the position of the tube or difficulty in obtaining aspirate.  The pH test is valueless if patients are on acid suppression, and if there is any doubt, or any other reason, an x ray is needed. Checking the position of a tube by injecting air through it and listening for bubbles with a stethoscope is unreliable.


  1. British Society of Gastroenterology Guidelines for enteral feeding in adult hospital patients

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