A22. Parenteral nutrition

Malnutrition is a serious problem that increases the risk of morbidity and mortality and has high incidence among critically ill and postoperative patients. Most of these patients (postoperative, sepsis, severe burn injury, etc.) have hypermetabolism and increased protein catabolism. Nutrition support in the form of enteral or parenteral nutrition is used.

The indications are as follows:

• Patients unable to eat orally
  • Inability to swallow (stroke, oesophageal cancer, injury)
  • Low GCS (unconsciousness)
  • Acute pancreatitis
  • Obstruction of the GI tract (ileus)
• Patients with impaired absorption
  • Inflammatory bowel disease
  • Short bowel syndrome
• Patients not willing to eat
  • Chemotherapy-induced nausea
  • Severe pain
  • Psychiatric disorders (anorexia nervosa, etc.)
• Patients with extreme nutrient demands
  • Severe burns

Consequences of malnutrition

• Impaired immune function
• Diaphragm atrophy -> decreased respiratory capacity
• Hypoalbuminaemia -> oedema, altered effect of medications, decubitus
• Increased insulin resistance
• Impaired haemostasis
• Atrophy of bowel wall -> bacterial translocation
• Various organ dysfunctions, including heart

These consequences increase the risk of complications, the duration of hospital stay, and increased mortality. Every single dollar spent on nutrition brings 3,25 dollars advantage in hospital care.

Enteral feeding

Enteral feeding means delivery of nutrition directly into the GI tract either orally or through a tube into the stomach, duodenum, or jejunum. Except for the oral form, this requires placement of a feeding tube, like a nasogastric, orogastric, or nasojejunal tube, or an enterostomy. In the oral form, the patient drinks liquid formulas per os. Enteral feeding is always preferred to parenteral feeding, because of the following advantages:

• Mucosal atrophy is prevented
• Metabolic complications occur less frequently
• Blood stream infections occur less frequently
• It is cheaper

Some contraindications include:

• Mechanical ileus
• Acute abdomen
• Recent GI anastomosis
• Intestinal ischaemia

Special formulations exist for special needs. For fluid-restricted patients, a more concentrated formulation exists. For patients with renal failure, an electrolyte-restricted formulation exists.

Enteral feeding is usually given in 10 – 30 mL/hour. The bed should be at an angle to prevent aspiration.

Parenteral feeding

Parenteral feeding means delivery of nutrition directly into a peripheral or central vein. It has many disadvantages compared to enteral feeding and is therefore used as a last resort. The nutrient formula must be administered through a central venous line. In case of bowel dysfunction or no oral intake > 5 days, parenteral nutrition is the first choice. Some of the disadvantages include:

• Atrophy of disuse of the GI mucosa and villi
  • -> complications when returning to oral/enteral feeding
  • -> translocation of microbes and toxins
• More expensive
• More labour intensive
• Possible interactions between parenteral feeding and drugs
• Risk of bloodstream infection
• Risk of metabolic complications
• Risk of complications of insertion of central line

Two forms exist, partial parenteral feeding (where a combination of enteral and parenteral feeding is used), and total parenteral feeding.