Nutritional support is recognized as being necessary in many hospitalized patients.
Principles of Nutritional support
Some form of nutritional supplementation is required in those patients who cannot eat, should not eat, will not eat or cannot eat enough. It is usually necessary to provide nutritional support for:
- all severely malnourished patients on admission to hospital
- moderately malnourished patients who, because of their physical illness, are not expected to eat for more than 3-5 days
- normally nourished patients not expected to eat for more than 5 days or eat less than half their intake for more than 8-10 days.
Enteral rather than parenteral nutrition should be used if the gastrointestinal tract is functioning normally.
Nutritional requirements for adults
A polymeric diet with whole-protein and fat can be used, except in patients with severely impaired gastrointestinal function who may require a predigested (i.e. elemental) diet. In these patients, the nitrogen source is purified low-molecular-weight peptides or amino acid mixtures, with sometimes the fat being given partly as medium-chain triglycerides.
Daily amounts of diet vary between 2 and 2.5 L and the full amount can be started immediately.
Hypercatabolic patients require a high supply of nitrogen (15 g daily) and often will not achieve positive nitrogen balance until the primary injury is resolved.
The success of enteral feeding depends on careful supervision of the patient with monitoring of weight, biochemistry and diet charts.