Chapter 26 PRACTICAL ISSUES IN NUTRITION AND SUPPLEMENTATION IN GASTROINTESTINAL DISEASE

KEY POINTS

• In upper gastrointestinal obstruction, endoscopic techniques facilitate access to the normal functional bowel distal to the obstruction, and thus restore normal digestion and absorption. It is imperative to simultaneously decompress the stomach proximal to the obstruction when feeding distally in order to avoid secretion build-up in the stomach.

• In lower gastrointestinal obstruction, the treatment is early surgery or total parenteral nutrition (TPN).

• Intestinal adaptation to intestinal loss may take up to 2 years. Thus, strong initial support is needed to optimise conditions for adaptation.

• The secret of adaptation is to make the remaining intestine work overtime.

• Tailoring TPN for the individual patient is essential.

• If less than 200 cm of small intestine without colon is present and IV supplementation becomes necessary, the condition is regarded as ‘small bowel intestinal failure’. This is also the case if less than 50 cm of small intestine remains with colon, and TPN or home TPN becomes essential for survival.

• In intestinal fistulae the volume of output provides a good index of the site of the fistula.

• Treatment for low output fistulae is not TPN. Oral feeding should continue.

• Be wary of bowel rest in sick patients.

INTRODUCTION

The function of the bowel is to digest and absorb food. Consequently, it is no surprise that disorders of the gastrointestinal tract are associated with nutritional problems. In chronic gastrointestinal disorders, the situation becomes complicated by the secondary effects of malnutrition on digestive function. The mucosa has one of the highest protein turnover rates of any organ within the body, and the synthesis of pancreatic enzymes is directly dependent on an abundant supply of amino acids. Thus, in chronic malnutrition, digestive and absorptive function becomes impaired, leading to a vicious cycle of malabsorption, maldigestion, malabsorption, etc.

Equally important to realise is the tremendous depth of reserves in digestive and absorptive function. For example, we can survive following the loss of >90% of the small intestine if the colon remains intact. Similarly, maldigestion and fat malabsorption only occurs after we have lost >90% of our pancreatic enzyme secretion. However, it must be remembered that adaptation to loss takes time; in the situation of the small intestine up to 2 years. Consequently, strong initial support will be needed to optimise conditions for adaptation to occur.

NUTRITIONAL PROBLEMS

Management options for various nutritional problems are summarised in Figure 26.1.

FIGURE 26.1 Nutritional problems.

NPO = non per os; PEG = percutaneous endoscopic gastrostomy; PEG-J = percutaneous endoscopic gastrostomy with post-pyloric J extension; PEJ = direct endoscopic jejunostomy; TPN = total parenteral nutrition.

Intestinal obstruction

In the days prior to total parenteral nutrition (TPN), intestinal obstruction was a fatal condition unless early surgery could correct the cause. In the 1970s and ’80s, TPN was exclusively used to stabilise the patients before surgery could be performed. In the short term, this was usually successful, but when continued >2 weeks, complications began to outweigh benefits.

TPN therapy

• Benefits

– Prevents fluid and electrolyte deficiencies

– Maintains nitrogen balance

– Prevents weight loss

– Maintains life

• Risks:

– It is unphysiological to feed directly into the right side of the heart

– Catheter sepsis

– Central vein thrombosis

– Hyperglycaemia

– Intestinal stasis:

• Small intestine bacterial overgrowth

• Mucosal atrophy and bacterial translocation

• Endotoxaemia

• Cholestasis

• Pro-inflammatory cytokine over expression

– Liver disease

Upper gastrointestinal obstruction

Because of concerns about TPN, endoscopic techniques have been developed to gain access to the normal functional intestine distal to the obstruction, and thus restore normal digestion and absorption.

• Oesophageal obstruction (e.g. cancer, stenosis, dysmotility):

– Endoscopic dilation

– Stenting

– Percutaneous endoscopic gastrostomy (PEG).

• Gastric, duodenal and proximal jejunal obstruction:

– Endoscopic dilation

– Stenting

– Percutaneous endoscopic gastrostomy with post-pyloric J extension (PEG-J)

– Direct endoscopic jejunostomy (PEJ)

– Double-lumen nasogastric decompression—jejunal feeding tube.

Note: It is imperative to simultaneously decompress the stomach proximal to the obstruction when feeding distally, as secretion will build up in the stomach leading to vomiting and possible aspiration.

Lower gastrointestinal obstruction

It is impossible to feed proximally with an intestinal obstruction because motility will be impaired and feed and secretions will build up without a chance for absorption to occur, producing vomiting. Consequently, the only alternatives are early surgery or TPN.

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