What is the purpose of a Nasogastric (NG) tube?

Purpose of a Nasogastric (NG) Tube

The primary purpose of a nasogastric (NG) tube is to provide temporary access to the gastrointestinal tract for enteral feeding and/or gastric decompression through a flexible synthetic tube inserted via the nostril into the stomach. 1

Primary Functions

• Enteral Feeding: NG tubes allow delivery of nutritional support directly to the stomach, bypassing the oral route when a patient cannot eat normally 1, 2
• Gastric Decompression: Used to relieve pressure in cases of enteral obstruction or to remove gastric contents 1
• Medication Administration: Provides a route for delivering medications when oral intake is not possible 3

Types and Placement

• Fine Bore Tubes (5-8 French gauge): Most commonly used for feeding purposes 1
• Large Bore Tubes: Used when stomach aspiration is required, though these should be avoided when possible as they increase risks of gastric reflux, aspiration, and irritation to the nose and esophagus 1
• Placement Method:
  • Typically inserted at bedside by passing an 8-12F tube into the stomach after lubrication 1
  • Patient's head is flexed and they may take sips of water to assist passage 1
  • Position confirmation via radiography is essential before initiating feeding (auscultation alone is unreliable) 1, 4

Duration of Use

• NG tubes are intended for short-term use (typically less than 4-6 weeks) 1
• For longer-term feeding requirements (>4-6 weeks), more permanent access such as percutaneous gastrostomy should be considered 1

Advantages and Limitations

Advantages:

• Relatively simple bedside placement procedure 1
• Allows for immediate nutritional support or decompression 1
• Less invasive than percutaneous alternatives 1

Limitations:

• Prone to dislodgement or inadvertent removal 1
• Risk of clogging due to small diameter 1
• Patient discomfort and potential for nasal/esophageal irritation 1
• Requires radiographic confirmation of placement to avoid potentially fatal complications 1, 5

Safety Considerations

• Misplacement into the trachea during insertion can lead to serious complications 4
• Proper verification of tube position is critical before initiating feeding or medication administration 4, 5
• Radiography remains the gold standard for confirming correct placement 4
• pH testing of aspirate is recommended over older litmus testing methods 4

Clinical Applications

• Neurological disorders affecting swallowing (stroke, multiple sclerosis, etc.) 1
• Unconscious or ventilated patients requiring nutritional support 1
• Upper GI obstruction requiring decompression 1
• Head and neck cancers or trauma affecting normal feeding 1
• Critical illness with increased metabolic requirements 1

When considering NG tube placement, it's important to recognize that while they are valuable for short-term use, they have higher dislodgement rates compared to percutaneous devices, which may be more appropriate for patients requiring longer-term enteral access 1.