Principles of infant nutrition
Nasogastric feeding
Learning outcomes
Having read this chapter, the reader should be able to:
Nasogastric (NG) tubes may be used in both adults and babies. They are, as the name suggests, a tube which passes through the nose (or mouth, orogastric), into the oesophagus and through into the stomach. They have two main uses:
Adult NG tubes are rarely seen in maternity, occasionally one is used to empty the stomach prior to a rapid caesarean section in which a general anaesthetic is to be administered, or women who are nil by mouth with a complication, e.g. paralytic ileus, may need continuous drainage of the stomach. Inserting a tube into an adult is very similar to that in a neonate, except that the woman (if permitted) assists by taking sips of water so that as she swallows, the tube is advanced into her stomach. This chapter considers neonatal NG tube insertion: safety, feeding and removal. Safety is an issue of particular concern.
Considerations
Feeding via a nasogastric (NG) tube is the most unnatural method of feeding. Wherever possible, a baby is breastfed. Breastfed preterm infants were able to move to enteral feeds faster than formula-fed infants, the breast milk providing better nutritional and developmental properties (Entwistle 2013). If the gestation or clinical condition is such that feeding the baby at the breast is not possible, then expressed breastmilk should be given via a suitable alternative route, e.g. cup or tube. There are many important aspects to feeding – sociability, opportunity to show love and affection, close physical and eye contact, appetite control, to name but a few. If tube feeding is the principal means of nutrition, wherever possible, the parents are encouraged to feed with these aspects in mind. In some instances tube feeding may be accompanied by, for example, short spells of breastfeeding or cup feeding. Spells at the breast aid the milk supply and make the transition to full breastfeeding easier.
An important part of digestion begins in the mouth, this is unfortunately missed when using a tube. Jones & Spencer (1999) also note that significant fat globules can adhere to the inside of the tube and so render lesser nutrition than is expected. These and other disadvantages (unsightly, easily removed, damage to the skin) often make it a short-term measure.
There have also been several alerts in the last decade from the National Patient Safety Agency (NPSA) about the positioning and safe use of NG tubes. A number of deaths have been caused by misplacement of the tube. The alert applies to all age groups, but in 2005 they released an alert specifically for use with neonates (NPSA 2005). In 2012 they reiterated their advice, suggesting that tubes that are misplaced and cause harm or death are ‘never events’, events that should never happen in modern healthcare. Misplaced tubes, i.e. misplaced into the lungs instead of the stomach, can cause death, even minor incidents can cause aspiration pneumonia (NPSA 2012).
The midwife is most likely to encounter tube feeding in special care baby units, the midwife also has a role in educating and supporting parents who may need to undertake NG tube feeds safely at home.
Nasogastric/orogastric tubes
Small (fine-bore) tubes are used for neonates. They are sterile, radiopaque and have visible external markings. Those used for older children or adults may have a guide wire that is used for insertion and can be cleaned, dried, and stored (name labelled) for future use. Tubes made from PVC should be changed after 7 days, polyurethane after 30 days. The tube is always checked to make sure it is complete before insertion. It may be lubricated with sterile water before insertion, but not any other lubricant. A tube that appears blocked should have 1–2 mL of air put down it, if this does not solve the problem, it is removed and replaced.
Traditionally the NEX – nose to ear to xiphisternum measuring system – has been used for neonates to determine the appropriate length for tube insertion. However, Cirgin Ellett et al (2011) propose that this distance is regularly too short and that the newer NEMU (nose to ear to midpoint between xiphisternum and umbilicus) should be used. They point out that other studies are yet to report on other measurements, including body weight, but agree that NEX is an inappropriate measure. The reader should consider their local protocol; this text currently demonstrates NEX as its guideline.
Safety considerations
As mentioned, feeding tubes can migrate, or may not have been placed correctly to start with. As well as the lungs, tubes can sometimes be found in the oesophagus or duodenum or coiled or kinked within the oral cavity. There are several methods previously advocated to check NG tube placement; they are no longer valid. These methods should not be used to assess an NG tube position (NPSA 2005):
The only recommended method of checking that the tube is in the stomach is the aspiration and testing of gastric aspirate (see below). The NPSA (2005) have issued specific guidance for the use of NG and orogastric tubes in neonates. Their guidance surrounds the critical issues:
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