Chapter 19. Enteral and Parenteral Nutrition

Malnutrition = “An acute, subacute or chronic state of nutrition, in which varying degrees of overnutrition or undernutrition with or without inflammatory activity have led to a change in body composition & diminished function.” (A.S.P.E.N. Board of Directors; http://www.nutritioncare.org/Library.aspx)

Malnutrition Risk Factors

• ↓ absorption state: gastric bypass surgery, ulcerative colitis, Crohn's disease, short-bowel syndrome
• Chronic disease: end-stage liver or renal disease, diabetes, chronic wounds/infection, alcohol/substance abuse, cachexia (cancer, HIV/AIDS wasting, cardiac)
• ↑ metabolic needs: trauma, burns, traumatic brain injury (TBI), sepsis
• Involuntary weight Δ >10% usual body weight (UBW)/6mo or >5% UBW/1mo
• ↓ appetite/food intake →↑ risk NPO ∼7–10d (less if additional risk factors)
• ≥20% below ideal body weight (IBW)

Weight Calculation

• IBW ♀ = 45kg + 2.3kg/in >5ft; IBW ♂ = 50kg +2.3kg/in >5ft
  • Use actual weight unless: ABW 20–30% > IBW, BMI >25–30kg/m2
  • NBW = IBW + 0.25 (actual weight – IBW)
    • Use adjusted body weight for nutritional calculations if ABW ≥30% IBW
• Interpreting weight → compare dry weight vs IBW
  • Factors that alter weight interpretation: edema/ascites, diuretics, fluid shift

Select Feeding Route

• Oral feeding preferred → enteral (EN) & parenteral (PN) feedings reserved for those unable to take PO
• Enteral Feeding: preferred if GI tract functional
  • Indications: functioning GI tract with poor or no PO intake, inadequate PO intake for >7d, malabsorption, hypermetabolic states, complications of pregnancy
    • Initiate within 24–48h; advance as tolerated; can feed through stomach (gastric) or small intestine (duodenal/jejunal)
  • Enteral formulations:
    • Immune modulating: major elective surgery, trauma, burns, head/neck cancer, critically ill patients on ventilation
    • Anti-inflammatory: acute lung injury, ARDS
    • Soluble fiber-containing formulations → diarrhea
  • Monitoring → residual Q4–6h or prior to bolus feeding; chem-7, Mg++, Ca++, PO4 2–3 times/wk; triglycerides, CBC, nitrogen balance & hepatic panel weekly
• Parenteral feeding: only for nonfunctioning or inaccessible GI tract
  • Indications: GI tract malabsorption, malnourishment with limited nutrient absorption via the GI tract, severe pancreatitis, critical illness with EN contraindicated, & bowel ischemia
  • Administer via central venous catheter (CVC), when possible ( ↑ osmolarity); peripheral vein infusion ...