Links between malnutrition and infection are established

Studies have demonstrated that malnutrition is one of the most significant factors of wound drainage and subsequent periprosthetic infection.

Javad Parvizi

The importance of nutrition on surgery was first recognized in 1930s, when surgical outcomes were noted to be adversely affected by malnutrition. In 1936, Cuthbertson’s descriptions of the adverse effect of malnutrition on his patients made orthopedic surgeons aware of this relationship. Although this connection was recognized, there was little to be done for hospitalized patients for the next 30 years.

In 1968, Dudrick and colleagues at the University of Pennsylvania showed the nutritional parameters of patients could be controlled in the hospital with parenteral nutrition. This advance led to efforts to correct the nutritional parameters of hospitalized patients, especially those undergoing surgery.

Nutritional assessment tools

Once dominion over nutritional status had been established, it became necessary to cultivate parameters within which a physician could monitor a patient’s nutritional status. This was a complex effort and one many feel is ongoing. Although batteries of tests combined with clinical findings are currently available to assess malnutrition (see Table), there is no universal agreement as to what constitutes malnutrition. However, it is fair to state that most experts would agree that low albumin (and/or pre-albumin), low transferrin, and low lymphocyte count are indicative of nutritional distress and may require correction prior to an elective surgery.

There is no dispute that malnutrition imparts a number of adverse physiological changes that compromise surgical outcomes. It is a known fact that a malnourished patient is more likely to have problems with wound healing. The question, and subject of this article, is: What do we know about the relationship between malnutrition and infection?

Scrimshaw and colleagues wrote in 1959, “The idea that nutritional deficiencies and infections have something to do with each other follows from the historical association between famine and pestilence.”

However, while it is well established that malnutrition increases susceptibility to complications, the exact relationship between preoperative malnutrition and postoperative infection rates in orthopedic patients has remained clouded. Numerous hypotheses have been proposed. Smith elegantly postulated the possible relationship between malnutrition and postoperative infections. His reasoning was expansive and included:

• a decrease in angiogenesis due to lack of protein substrate and therefore poor wound healing;
• third-space fluid losses due to lack of blood protein causing pulmonary edema, poor pulmonary perfusion and resultant poor blood oxygenation;
• a decrease in lymphocytes, cell mediated immunity, phagocytic leukocytes, complement proteins and granulocyte function all contributing to a lack of host defense mechanisms;
• and a lack of essential vitamins and minerals which causes, among other things, a decrease in the functioning of T lymphocytes and natural killer cells.

All of these consequences of malnutrition combine to create a welcoming environment for invading bacteria.

Complications

Jensen, Jensen and colleagues studied complications related to orthopedic surgeries performed on malnourished patients. They measured triceps skin folds, arm-muscle circumference, creatinine height index, transferrin concentration, albumin concentration, total lymphocyte count (TLC) and skin-antigen testing in 129 patients, undergoing elective and trauma surgery, at regular intervals pre- and postoperatively when applicable. Of the patients who developed complications postoperatively, 59% had at least one severely abnormal visceral protein measurement — albumin less than 3.0 g/dL; transferring less than 150 mg/dL; TLC less than 1,000 cells/mm³; and anergy to skin-antigen testing equal to 0 mm of induration.

Of 31 postoperative wound complications, 27 were in nutritionally depleted patients. For patients undergoing elective hip surgery, they found that arm-circumference was the best single predictor of complications; however, skin-antigen testing, TLC, albumin and transferrin concentrations indicated a tendency towards increased complications as well.

An article written by Lavernia and colleagues analyzed the relationship between nutritional parameters and short-term arthroplasty outcomes. They found that in patients with a serum albumin less than 34 g/L or TLC less than 1,200 cells/µL, the cost and length of hospital stay were both significantly increased. A significant increase in the comorbid index was seen in those with low albumin, and a significant increase in anesthesia time and number of consults was shown in those with a reduced TLC. However, a distinct relationship between malnutrition and infection was not found, which the authors attributed to a small sample size.

A study from our institution demonstrated that one of the most significant factors for wound drainage and subsequent periprosthetic infection was malnutrition.

Obesity and malnutrition

Within the current definition of malnutrition, as stated by Soeters and colleagues, obesity is a form of malnutrition. This occurs do the consumption of empty calories – calories acquired through foods that are processed and packaged to provide long-term shelf life, cheap convenience and exciting flavors but lack necessary vitamins and minerals. Patients can be overweight and undernourished, as paradoxical as that may seem.

Malnutrition often results from bariatric surgery. The nutritional status of bariatric patients after surgery was researched and baseline micronutrient deficiencies were discovered. A review article by Kaidar-Person and Rosenthal into current investigations of micronutrients in obese patients prior to bariatric surgery had interesting findings, although there is a lack on consistency in the definition of deficiency and the assays used to test for them.

While not unanimous, obesity has been linked to deficiencies in folate and vitamins A, B12, B1, C, and E. Deficiencies in vitamin D (25-OH-D3), selenium and zinc have also been seen across the board, which may explain the connection between obesity and infection.

Considering these data, a study of malnutrition and infection in orthopedic surgery patients should be undertaken. Physicians also need a fast, efficient way to evaluate malnutrition in preoperative patients. This nutritional information could also be used to determine the aggressiveness of postoperative care when an infection is suspected, to prevent a harmful delay in treatment.

For more information:

• Patricia Hansen and Javad Parvizi, MD, FRCSC, can be reached at Rothman Institute of Orthopaedics at Jefferson, 925 Chestnut St., 2nd Floor, Philadelphia PA 19107; 267-399-3617; e-mail: parvj@aol.com.