Total parenteral nutrition

Nutrition

Daily requirements
- Energy = 25-35 Kcal/kg/day
- Protein = 1 g/kg/day non-stressed, 1.2-1.5 g/kg/day post-op
- Fluid = 25-35 ml/kg/day
Always use gut first, if it works
- Short-term (4-6 weeks)
  - NG/OG/NJ/OJ
- Long-term (>4-6 weeks)
  - PEG (percutaneous endoscopic gastrostomy) tube (G-tube)
  - PEJ tube (J-tube)
  - G-J tube, G-tube for decompression, J-tube for feeding

Consider goals of care
Poor nutrition status
10% / 2-3month weight loss, and <75% ideal body weight, and
- Inadequate intake for 7+ days
GI disorder predicted to prevent the use of the GI tract for 7+ days

Nutrients
- Dextrose 3.4 Kcal/g
- Amino acids 4 Kcal/g
- Lipids 10 Kcal/g (10%) or 2 Kcal/g (20%)
- Electrolytes based on clinical picture
Formula
- Calculate daily energy requirements (~30 Kcal/kg) ~2000Kcal for 65kg
- Calculate daily fluid requirements (~30 mL/kg) ~2000mL for 65kg
- Calculate daily protein requirements (1-1.2 g/kg), concentration within total daily fluids, and energy provision (4 Kcal/g) ~65g = 3.25% of 2000mL and 260Kcal
- Calculate energy provided by lipid (usually 20% 250mL bag)
  - 250mL of 20% = 500Kcal
- Calculate energy deficit and provide as dextrose (3.4Kcal/g) in percentage of daily fluid
  - 2000Kcal -- 260Kcal -- 500Kcal = 1240Kcal deficit = 365g dextrose deficit
  - 265g dextrose in 2000mL fluid = 18.25% concentration
- Finish by providing the concentrations of protein and dextrose along with flow rate, and lipids separately
  - 3.25% amino acids/18.25% dextrose @ 83mL/h with 250mL 20% lipids

Dextrose metabolism
- Hyperglycemia
- Hepatic steatosis
- Elevated CO2 prodction
Amino acid metabolism
- Prerenal azotemia
Hypertriglyceridemia (both from the formula itself and from dextrose overfeeding)
- Pancreatitis
Hepatobiliary complications
- Steatosis
- Cholestasis
- Gallbladder stasis