The Better Method in Tube Feeding
Enteral (“through the gut”) feeding is recognised as the preferred method of delivering nutrition, over intravenous methods, for those who are unable to maintain nutrition on their own. It is the most natural way of nutritional delivery, while it also maintains the defence systems of the gut for better immunity, and costs less compared to intravenous nutrition.
WAYS OF DELIVERY
For those who are unable to ingest or imbibe safely because of various reasons, including neurological conditions, tumours of the oral cavity or functional decline, tube feeding is the most common way of delivering enteral nutrition.
The most common tube employed is the nasogastric (NG) tube, which is a long plastic or silicone tube that is inserted through the nostrils and oesophagus, and ends in the stomach. While this is the simplest method, it has its own set of drawbacks.
For example, it needs to be changed frequently (every two weeks), can be irritating to the nostrils and throat, and can potentially promote aspiration pneumonia. Aspiration pneumonia is a potentially serious condition where food contents backflow from the stomach into the lungs causing infection.
The constant presence of an NG tube in the oesophagus keeps the sphincter open and potentially promotes the backflow of gastric contents.
There have also been rare cases where NG tubes were accidentally inserted into the airways. If undetected, this can potentially lead to fatal consequences.
GASTROSTOMY TUBES
Gastrostomy tubes are an increasingly common alternative to NG tubes, whereby a shorter tube is inserted through the abdominal wall directly into the stomach in a simple surgical procedure.
A gastrostomy tube provides a shorter conduit for the delivery of enteral nutrition at faster speeds (as the tube is often wider) and it does not encourage aspiration pneumonia. Being shorter and wider tubes, gastrostomy tubes are longer lasting and have a lower risk of being blocked compared to NG tubes. These tubes are typically licensed to be used for up to 12 months before a change is required.
Patients requiring long-term tube feeding typically enjoy a much higher quality of life with a gastrostomy tube as compared to an NG tube. However, gastrostomy tubes require minor surgical procedures for its insertion.
METHODS OF GASTROSTOMY TUBE INSERTION
Gastrostomy tubes are most commonly inserted with the help of an endoscopy. Tubes that are inserted using this method are known as PEG (percutaneous endoscopic gastrostomy) tubes. In more uncommon scenarios, laparoscopic (key-hole) surgery may be required for gastrostomy tube insertions.
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While a PEG tube is less prone to blockage compared to an NG tube, it is still recommended to be flushed regularly with water after every milk feed. Daily flushing with an effervescence soda like Coca-Cola is also recommended to keep the tube patent. A simple key-hole gauze and micropore tape dressing is always required at the insertion site. This dressing is typically changed once every 3-4 days.
TECHNIQUES OF PEG TUBE INSERTION
PEG tube insertions are done under intravenous sedation. The patient is fully sedated and unable to feel any sensation. The procedure is typically performed in a hospital setting. It usually takes about 30 minutes and requires a stay of three days. With the patient under sedation, a gastroscope is gently inserted into the stomach under direct vision. The stomach is then inflated with CO2
(carbon dioxide), and with the help of the light on the scope, an insertion site is identified in the abdominal wall through transillumination and digital indentation. This is a common step in PEG tube insertion techniques, after which the procedure varies on whether a pull or push technique is employed.
PULL TECHNIQUE
In the pull technique, a guidewire is passed through an introducer needle that is inserted through the abdominal wall into the insufflated stomach. This guidewire is then caught by a snare from the scope and pulled backwards with the scope as it is then withdrawn out through the mouth. This oral end of the now external guidewire is then attached to the PEG tube.
Once securely fastened, the abdominal end of the guidewire is then pulled (hence the “pull technique”), drawing the attached PEG tube through the mouth, oesophagus and stomach, where it will eventually surface through the insertion site. The pulled PEG tube is then fastened to the abdominal wall and ready to be used.
PUSH TECHNIQUE
In the push technique, the gastroscope is kept in the stomach throughout the whole procedure as a visual guide to insertion. With the stomach insufflated and the insertion site identified, special gastric fixation sutures are passed into the stomach through the abdominal wall. These fixation sutures are delivered via a needle and serve to securely attach the stomach to the undersurface of the abdominal wall.
Once the stomach is securely fastened, the PEG tube is then inserted into the secured stomach through an incision on the abdominal wall that is gradually enlarged through a series of dilators.
As an additional means of fixation, the PEG tube used in the push technique has a securing balloon that holds the tube securely to the abdominal wall. The fixation sutures are dissolvable and detach themselves in a week once the stomach is fully secure. The tube is immediately used for feeding.
COMPARING THE PULL AND PUSH TECHNIQUES
The pull technique is the traditional method of insertion that most endoscopists and surgeons started with. However, there is a significantly higher risk of insertion site infections and wound breakdowns with this method.
This is mainly due to the fact that the tube is trawled through the oral cavity during insertion, bringing oral bacteria into the abdominal wall. These risks are only slightly ameliorated with prior oral preparation and prophylactic antibiotics.
The pull technique is also unsuitable for patients with oesophageal narrowing as the tube needs to be pulled through the oesophagus. Furthermore, the PEG tubes used in the pull technique are typically mushroom-tipped tubes that require a repeat gastroscopy for the first change. On the other hand, the push technique is the newer technique that draws on innovation in surgical instrumentation.
The fixation sutures and peel-away dilator sheaths are the backbone of this technique, allowing the PEG tube to be safely “pushed” into the stomach. There is a very low risk of wound infection and consequent wound breakdown as the abdominal wall is sterilised before insertion. The stomach is naturally sterile because of acidity, and the tube entirely avoids the contamination of the oral cavity during insertion.
As the push technique utilises balloon-tipped tubes, subsequent tube replacements are simple bedside affairs that can be performed even at the comfort of the patient’s home by a trained professional. In the push technique, there is also an added option of utilising a shorter profile gastrostomy tube that is more convenient and discreet. This is especially suitable for ambulant patients who require tube feeding.
PEG TUBE MAINTENANCE
While a PEG tube is less prone to blockage compared to an NG tube, it is still recommended to be flushed regularly with water after every milk feed. Daily flushing with an effervescence soda like Coca-Cola is also recommended to keep the tube patent. A simple key-hole gauze and micropore tape dressing is always required at the insertion site.
This dressing is typically changed once every 3-4 days. In the unlikely event that the PEG gets accidentally dislodged, it is essential that a fresh tube be inserted into the same tract within 24 hours. This is because the PEG tract will close and seal up entirely within 24-48 hours of displacement.
INDICATIONS FOR PEG TUBE INSERTION
PEG tubes are suitable for patients who require tube feeding for more than 30 days, and who have moderate to severe protein calorie malnutrition. It is also suitable for those with a history of aspiration pneumonia on NG tube feeding, and for patients who are tube feeding dependent but desire a higher quality of life at the same time.
