Enteral Nutrition

ICU patients undergo initial catabolism with significant protein loss.

Nitrogen balance

Can be calculated: Loss (urine + faeces + invisible) – intake (1g nitrogen gor 6.25g protein)

Loss via faeces and insensitive are small and therefore estimated 

Urinary urea nitrogen (UUN) can be a poor estimate in patients with burns, renal failure and enteric fistulas

When to start

  • As soon as possible
  • Definively within 14 days (increased mortality when started later)
  • Ideally within 7 days
  • Burns and trauma within 24h if possible

Complications of overfeeding

  • Hyperglycaemia
  • Uraemia (due to excessive nitrogen load)
  • Hypercarbic respiratory failure (due to excessive Carbonhydrate load)
  • Hepatic steatosis
  • Hyperosmolar-non-ketonic coma
  • Hyperlipidaemia

Nutritional expenditure

Can be measured by

  • Indirect calorimetry (gold standard)
  • Fick principle using HbxCOx(SaO2-SvO2)/100

Rough estimation of basal energy expenditure

  • Predictive calculations eg Harris Benedict equation (may be superior to Fick principle)
  • 20-30kcal/day per kilo body weight
  • 80kg à 1600-2400 kcal/day

            mild infection, postoperative                 + 10%

            severe sepsis                                        + 30-50%

            burns                                                   + 30-70%

Protein requirement

1g/kg/day (equals 0.15g nitrogen/kg/day)

            burns                                                   +100%

Route of nutrition

Whenever possible enteral nutrition should be preferred

  • Lower cost        
  • Lower rate of infection
  • Intravenous lipid may reduce neutrophil and RES function
  • Direct nutritional effect on gut mucosa –  enhanced barrier function
  • Physiological emptying of the gallbladder

Enteral feeding may be associated with underfeeding (in impaired motility)        

Access

Enteral

Orogastric or nasogastric 12-14F

            BOS# is contraindication for nasogastric

Jejunal tubes do not reduce risk of aspiration

Jejunal preferred for pancreatitis to reduce pancreatic stimulation

PEG

Parenteral

CVC, PICC line

Regimen

Enteral

Starting with 30ml/h, increasing to target rate

Checking residual volumes q4h

Prokinetics if residual volumes remain high

Protocol useful

Importance of the pattern is unclear

            Rest periods allow re-acidification and possibly reduce nosocomial pneumonia

Parenteral

Start at target rate

Must be weaned to avoid rebound hypoglycaemia

Food energy

Carbohydrates 4 kcal/g

Proteins 4 kcal/g

Fat 9 kcal/g

Enteral

Different compositions available (e.g. Pulmocare, Nephro, 2cal…)

Pareneteral

30-40% of calories via fat (eg lipid 20% 500ml/day =900kcal)

Monitoring

  • Albumin, Pre-Albumin
  • Transferrin
  • Lipid profiles

Complications

Enteral

  • Sinusitis
  • Misplacement of tube
  • Aspiration
  • Diarrhea (less with high-fibre products)
  • Metabolic (hyperglycaemia)
  • Refeeding Syndrome

parenteral

  • CVC related complications
  • Metabolic (hyperglycaemia)
  • Refeeding Syndrome (hypophosphataemia, hypokalaemia)
  • Rebound hypoglycaemia
  • Liver dysfunction (intrahepatic cholestasis, hepatic steatois)