Nutrition in Surgical Patients
Ronald Merrell, MD
Chairman of Surgery
Virginia Commonwealth University

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Carbohydrate
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Lipid
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Protein
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Trace elements
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Vitamins
What?

Who?
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Malnourished (>10% lean body mass)
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Incapable of eating (>10 days)

Why?
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Risks of malnutrition including infection, poor healing and higher mortality
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Malnutrition is exacerbated by physiological stress

When?
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Preoperative?
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Early?
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Late?
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---after initial resuscitation following injury or surgery

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Parenteral
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Enteral
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Total
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Partial
How?

Issues
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Metabolic response to injury
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Cytokines, inflammation, hormones
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Biology of substrates
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Enteral vs. Parenteral

“Ashen faces, a thready pulse and cold clammy extremities…”
The Ebb Phase
Cuthbertson, Quart. J.
Med.25:233,1932

The Ebb Phase
• Hypometabolic
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Hypothermic
• Hypoinsulinemic
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Hypoperfusion
• Hypercortisolism
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Hyperglucagonemia
• Hyperglycemia
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Hypercatecholemia

“The patient warms up,cardiac output increases and the surgical team relaxes…”
The Flow Phase
Cuthbertson. Lancet 1:233, 1942

The Flow Phase
• Hypermetabolic
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Hyperthermic
• Catabolic
• Hyperinsulinism
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Hypercortisolism
• Hyperglucagonemia
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High cardiac output

Nutritional Assessment
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Body weight
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Body mass index
• creatinine height index
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Serum proteins:albumin, prealbumin, transferrin
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Immune competence: lymphocytes, DH
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Nitrogen balance

Caloric Requirement
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Formula
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Indirect calorimetry
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PRN for nitrogen balance
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Approximation

Nutritional Requirements
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25 cal/kg/day
• carbohydrate ~70%
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Lipid 15-30%
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Protein 1.5-2.0g/kg/day. Not for calories
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Additional 50% to 100% for stress as in
ICU patients

Nutritional Goals
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Nitrogen balance
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Preserve or restore visceral protein
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Reduce morbidity
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Reduce mortality
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Reduce hospital stay

Early Enteral Feeding: a metaanalysis
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Eight prospective randomized trials with trauma and high risk surgical patients(118 enteral, 112 parenteral)
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Septic complications:enteral 18%, parenteral 35%
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Moore. Ann. Surg. 216:172,1992

Parenteral requirements
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Dilution in right heart return because of hyperosmolarity…….Central Venous Line
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Delivery of simple carbohydrate
(20%glucose)
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Lipid emulsion
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Amino acids

Enteral Requirements
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Delivery into the GI tract by tube with minimum risk of aspiration or patient effort
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Delivery of nutrients with minimal need for digestion
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Control of rate to prevent osmotic diarrhea

Advantages of enteral nutrition
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Easier
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GI bacterial translocation
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Cheaper
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Fewer specific complications

Nutrients with specific putative contributions
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Branch chain amino acids
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Glutamine
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Arginine
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Nucleotides
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Omega-3 fatty acids

Immune Enhancing Diet
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Arginine, nucleotide, fish oil
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Shorter stay, fewer infections
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Bower Critical Care Medicine. 23:436,
1995

Parenteral Nutrition
Immunosuppressive
IF...
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Poorly administered
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Hyperglycemia
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No nucleotides
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No arginine
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No taurine
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Excessive fats

Overfeeding with parenteral diets
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Carbohydrate: hyperglycemia, hypercarbia, fatty liver
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Lipids: hypertriglyceridemia, hypoxia, infection
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Protein: azotemia

Conclusions
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Nutrition is a powerful determinate of patient outcome
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The proper provision of nutrition is a component of basic patient care
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Nutrition is a precise and potentially very hazardous form of intervention