Nutritional support in surgical patients
Significant nutritional deficiency impairs healing, lowers resistance to infection and prolongs the recovery period. Malnutrition may be present preoperatively particularly in the elderly and patients with malignancy. Perioperative nutritional support may be necessary if the patient is unable to maintain sufficient intake to balance the increased postoperative nutritional requirement.
Enteral nutrition is the treatment of choice in all patients with a normal, functioning gastrointestinal tract. It is generally safer than intravenous nutrition and it helps to maintain the integrity of gastrointestinal mucosa. Liquid feeds either as a supplement or replacement may be taken orally, via a nasogastric tube or via a gastrostomy. Liquid feeds may be whole protein, oligopeptide or amino acid based. These also provide glucose, essential fats, electrolytes and minerals.
Parenteral nutrition is indicated when patients cannot maintain a sufficient calorie intake via the enteral route. Indications include intestinal resection, fistulae, motility disorders and extensive small bowel disease. Mixed preparations of amino acid, glucose and lipid are used with trace elements, vitamins and electrolytes also added.
Parenteral nutrition is hypertonic, irritant and thrombogenic. They should ideally be infused through some form of central venous access. Peripheral parenteral nutrition may cause significant injury if extravasation occurs. Other complications of parenteral nutrition include line infection and septicaemia, thrombosis and embolism, liver damage and metabolic disturbance (osmotic diuresis, acute hyperosmolar syndrome and electrolyte imbalances).