Enteral nutrition

Routes include nasogastric, nasoduodenal/jejunal, gastrostomy, and jejunostomy. Nasal tube feeding should be via a soft, fi ne-bore tube to aid patient comfort and avoid ulceration of the nose or oesophagus. Prolonged enteral feeding may be accomplished via a percutaneous/per-operative gastrostomy or jejunostomy. Enteral feeding provides a more complete diet than parenteral nutrition, maintains structural integrity of the gut, improves bowel adaptation after resection, and reduces infection risk.

Feed composition

Most patients tolerate iso-osmolar, non-lactose feed. Carbohydrates are provided as sucrose or glucose polymers; protein as whole protein or oligopeptides (may be better absorbed than free amino acids in ‘elemental’ feeds); fats as medium chain or long chain triglycerides. Medium chain triglycerides are better absorbed. Standard feed is formulated at 1Cal/mL. Special feeds are available, e.g. high fibre, high protein-calorie, restricted salt, high fat or concentrated (1.5 or 2Cal/mL) for fluid restriction.

Immune-enhanced feeds (e.g. glutamine-enriched or ImpactR, a feed supplemented with nucleotides, arginine, and fish oil) may reduce nosocomial infections, but no evidence of outcome benefit has yet been shown from large prospective studies.

Management of enteral nutrition

Once a decision is made to start enteral nutrition, 30mL/h full strength standard feed may be started immediately. Starter regimens incorporating dilute feed are not necessary. After 4h at 30mL/h, the feed should be stopped for 30min prior to aspiration of the stomach. Since gastric juice production is increased by the presence of a nasogastric tube, it is reasonable to accept an aspirate of <200mL as evidence of gastric emptying, and therefore, to increase the infusion rate to 60mL/h. This process is repeated

until the target feed rate is achieved. Thereafter, aspiration of the stomach can be reduced to 8-hourly. If gastric aspirate volume >200mL, the infusion rate is not increased though feed is continued. If aspirates remain at high volume, consider either prokinetics to promote gastric emptying (e.g. metoclopramide, erythromycin), bowel rest (especially if abdominal distension or discomfort increases), nasoduodenal/jejunal or parenteral feeding.

Complications

• Tube misplacement: tracheobronchial, nasopharyngeal perforation, intracranial penetration (basal skull fracture), oesophageal perforation.

• Reflux.

• Pulmonary aspiration.

• Nausea and vomiting.

• Abdominal distension is occasionally reported with features including a tender, distended abdomen, and an increasing metabolic acidosis. Laparotomy and bowel resection may be necessary in severe cases.

• Refeeding syndrome.

• Diarrhoea: large volume, bolus feeding, high osmolality, infection, lactose intolerance, antibiotic therapy, high fat content.

• Constipation.

• Metabolic: dehydration, hyperglycaemia, electrolyte imbalance.