Feeding tubes

A. Sparkes

Cats can be notoriously fussy about eating, both while hospitalized and postoperatively, and the importance of maintaining their nutritional status cannot be overemphasized. Adequate nutrition has many benefits including improving the patient’s well-being, optimizing healing and preventing re-feeding syndrome (see Chapter 6). This chapter aims to cover the indications and type of feeding tubes that are available for use in cats and the techniques of tube insertion.

General considerations

There are many reasons why a surgical patient may become inappetent, anorexic, or have inadequate nutritional intake (Box 12-1).

Box 12-1 Reasons for postoperative inappetence in cats

• Medical or surgical conditions directly affecting the alimentary tract

• Presence of uncontrolled pain

• Presence of uncontrolled nausea

• The stress of hospitalization

• Offering unfamiliar or unsuitable foods

• Development or induction of food aversion, e.g., by offering the cat food while it is feeling painful or nauseous

• Side effects of medications being used, e.g., opioids

• Presence of inflammatory cytokines

It is important that a full assessment is made of both the reasons for inadequate nutritional intake and the options available for overcoming these. Due to their unique nutritional requirements, cats should not be allowed to remain significantly inappetent or anorexic for longer than three days,¹ and particular care should be taken of surgical patients where, depending on their condition, nutritional demands may be appreciably higher and inadequate nutritional support may have serious consequences for recovery, morbidity and even mortality.

It is well recognized that providing enteral nutritional support, wherever possible, is far superior to attempting parenteral support, being more physiological, safer, less expensive, and preserving the structure and function of the gastrointestinal tract.² There are occasional situations where parenteral or partial parenteral nutrition is the only realistic option available, but for the vast majority of patients some form of enteral nutritional support can be used. However, the technique used may be dictated, at least to some extent, by the patient’s condition. The presence of orofacial or esophageal disease may, for example, preclude the use of certain tube feeding techniques such as nasoesophageal or esophagostomy tubes.

Although force-feeding, e.g., syringe feeding, is sometimes advocated for the short-term nutritional support of dogs and cats, this is not a technique that can be recommended, especially for cats. Force-feeding is inevitably a highly stressful procedure, and as such one that is likely to promote further inappetence rather than help resolve the situation. Additionally, it is very difficult to meet nutritional requirements by force-feeding and there is a significant risk of inducing aspiration of food with this technique.

Given the wide availability of other much more suitable forms of nutritional support (tempting of voluntary food intake, pharmacological stimulation of appetite, or tube feeding) there is no rationale for the use of force-feeding with the feline patient. Similarly, orogastric tube feeding is too stressful for the feline patient.

Tube feeding

Tube feeding is an important consideration in inappetent cats. Not every inappetent or anorexic cat will require nutritional support via tube feeding, but many will. Tube feeding should be instituted at an early stage for those cats that do not respond adequately to addressing the underlying causes of the inappetence, together perhaps with the use of appetite stimulants when deemed appropriate; or for those where more conservative measures are considered inappropriate,

In addition, tube feeding may be valuable to avoid inducing food aversion in some cats. Aversion to foods can develop when they are offered to patients when they are experiencing significant pain (especially gastrointestinal pain) or nausea. The cat may subsequently associate those feelings with the food that was offered and therefore refuse the food, even when the pain or discomfort has resolved. Where it is anticipated that pain or nausea may be difficult to fully control, tube feeding may be an important pre-emptive strategy to avoid inducing food aversion.

The three most common forms of tube feeding in cats are nasoesophageal tube feeding, esophagostomy tube feeding, and gastrostomy tube feeding (Table 12-1). In occasional patients, feeding via a duodenostomy or jejunostomy tube may be indicated. In the past, pharyngostomy tubes have also been advocated for tube feeding of dogs and cats, but these are now not recommended due to complications such as airway obstruction.²

Table 12-1

Overview of the three major forms of tube feeding in cats

Feeding tubes

The selection of feeding tube for any individual patient will depend on a variety of factors as listed in Box 12-2.

Box 12-2 Selection factors for feeding tubes in cats

• The anticipated duration of tube feeding. Nasoesophageal tubes are much less suitable for longer-term support, i.e., longer than one or two weeks

• The type of food available. Choices for nasoesophageal and jejunostomy feeding are much more restricted due to the narrow diameter of the tubes used

• The condition or disease being treated

• The presence or absence of diseases affecting the nose, mouth, pharynx, esophagus, or stomach

• The need for general anesthesia in the placement of any tube other than nasoesophageal tubes

• Owner concerns and abilities, especially if continuation of tube feeding in the home environment is anticipated

Duodenostomy and jejunostomy tubes

Orogastric feeding is preferable over feeding that bypasses the stomach, so duodenostomy and jejunostomy tubes are rarely used in cats. There are limited indications for their placement (Box 12-3). Direct surgical placement via the flank is the most common method used,³ and has been reported to have a low complication rate. A modified jejunopexy technique may reduce the risk of leakage around the site of tube entry into the jejunum.⁴ The reader is referred to Heuter (2004)³ and Daye et al (1999)⁴ for further details, but this chapter will focus on the three most commonly used techniques of tube feeding.

Box 12-3 Indications and placement for feeding cats via a duodenostomy or jejunostomy tube

Indications

• Where there is persistent vomiting and/or gastric outflow obstruction

• Where there is severe disease of the proximal intestinal tract

• In the face of severe pancreatitis (to reduced neuro-hormonal stimulation of the pancreas)

• Where altered (reduced) levels of consciousness may lead to high risk of aspiration if vomiting was to occur

Placement

• Surgically via the flank into the jejunum

• Transpyloric placement via a nasojejunal tube

• Transpyloric via a gastrojejunal tube, i.e., via a gastrostomy tube

Nasoesophageal intubation

Nasoesophageal tubes are very well tolerated by the majority of cats and have the important advantage of being inexpensive, easy to place and requiring no anesthesia (and usually no sedation) for their placement (Box 12-4). The use of nasoesophageal tubes is particularly valuable in providing short-term nutritional support, but esophagostomy or gastrostomy tubes should generally be considered if tube feeding will need to be provided for longer than around seven days. Additionally, other techniques must be used in cases where nasoesophageal tubes are contraindicated, such as esophageal or gastric dysfunction or persistent vomiting, or perhaps where more aggressive nutritional support is required (due to the wider range of feeds that can be used in wider bore tubes).

Box 12-4 Technique of nasoesophageal tube placement

The length of the tube to be inserted should be pre-measured and marked, by measuring the distance from the tip of the nose to the seventh or eighth intercostal space. This will ensure that the tip of the tube lies in the distal esophagus and not in the stomach itself, which helps to reduce the risk of reflux of gastric juice, vomiting and esophagitis.

Before passing the tube the nasal mucosa should be anesthetized by applying a few drops of a non-irritating local anesthetic, e.g., 0.5% proparacaine/proxymetacaine or 0.5–1% amethocaine. If necessary, the cat may also be sedated lightly to facilitate the procedure.

The tube should be lubricated with a water-soluble gel (a plain gel or 5% lignocaine gel may be used). The head should be held firmly in one hand and the nose tilted up a little, and the tube is then inserted into the anesthetized nose using the other hand in a ventromedial direction, aiming towards the base of the ear on the opposite side of the head (Fig. 12-1A). This should ensure the tube passes along the ventral nasal meatus and into the nasopharynx. If the tube lodges in the dorsal or middle nasal meatus it should be withdrawn and redirected ventrally. Passing the first 1–2 cm is often the most difficult as the skin around the external nare will not be anesthetized.