Feed hospitalized patients early for faster recovery

Feed hospitalized patients early for faster recovery

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Oct 01, 2008

Patients of any age may become malnourished from inadequate nutrient intake while in our care.

Malnutrition is not fully appreciated by most clinicians because it does not appear as a number on your laboratory data or physical exam. Hospitalized veterinary patients are more commonly malnourished due to a decreased total food intake.

The major consequences of malnutrition in sick or injured patients are decreased immunocompetence, decreased tissue synthesis and repair and altered drug metabolism. You can help heal the patient by feeding it.

Immunocompetence

The reciprocal relationship between nutrition and immunity has been recog-nized for centuries. A malnourished animal is more susceptible to infections, and a septic patient is more likely to be anorectic, which results in malnutrition.

Nutrient imbalances suppress immune function, which increases the risk of disease; conversely, certain diseases alter some nutrient requirements. Protein and (or) calorie malnutrition causes progressively poor responses in several components of the immune system, including significantly impaired cell-mediated responses, secretory IgA production, phagocytosis, complement function, antibody affinity and cytokine production.

Studies have shown that protein deficiencies that limit amino acid and nucleotide substrates for cell proliferation result in reduced numbers of circulating T lymphocytes, helper and suppressor cells.

Malnutrition also decreases immune function of existing cells through reduced complement secretions, less effective macrophage function and decreased killer-cell activity. Cytokine production and release are independently impaired in protein-calorie malnutrition.

The good news is that numbers of T4 helper cells and T8 cytotoxic suppressor cells in malnourished patients return to normal quickly with refeeding. Immunoglobulins and circulating antibodies are maintained at relatively low levels during malnutrition, but are highly responsive to appropriate refeeding stimuli.

Tissue synthesis and repair

Local tissue synthesis and wound healing depend on whole body nutrition. On the cellular level, amino acids and carbohydrates are needed for collagen and ground-substance synthesis. Fibroblasts require energy to synthesize the RNA, DNA and ATP necessary for protein anabolism. Migration of fibroblasts, epithelial and endothelial cells also requires energy.

The liver requires energy and protein specifically for synthesis of fibro-nectin, complement and glucose. The bone marrow requires nutrients for production of platelets, leukocytes and monocytes. On the organ level, transportation of these necessary components, plus oxygen to wound sites, require the muscular activities of respiration and cardiac work.

Tissue trauma and healing alter the normal cycle of protein turnover (synthesis and degradation) in the body. Protein turnover in perioperatively fed people had a 91 percent increase in protein synthesis with only a 10 percent increase in protein degradation (net gain), while perioperatively starved people had only a 50 percent increase in protein synthesis with a 79 percent increase in protein degradation (net loss).

Drug metabolism

Cellular activities are dependent upon, and regulated by, the coordinated actions of peptides, lipids, vita-mins and minerals as substrates, enzymes, coenzymes and cofactors of intermediary metabolism.

In short, all nutrients are essential for the maintenance of normal cellular structure and function.

Nutrient deprivation alters the normal metabolic synergy responsible for ion gradients, membrane potentials, production of high-energy phosphate compounds and antioxidant defenses. Protein-calorie deficiencies result in decreased:

1) hepatic biotransformation of certain antibiotics

2) concentrations of serum proteins that bind and transport drugs throughout the body

3) renal blood flow, which decreases the rate of drug elimination, increasing the possibility of drug toxicity.

Therefore, protein-calorie malnutrition may alter the normal or expected metabolism of certain drugs, which may in turn increase or decrease their therapeutic effect even when given at recommended dosages.

Animals receiving sufficient calories and protein are expected to have better, or near normal, drug distribution, meta-bolism and elimination than animals with protein-calorie malnutrition.