RN/DREXEL Home Study Program CE CENTER

CE credit is no longer available for this article. Expired July 2005

Originally posted August 2004

How to help wounds heal

SUE LEININGER HOGAN, RN, MSN

SUE LEININGER HOGAN is an advanced practice nurse at Allegheny General Hospital in Pittsburgh.

Successful wound healing depends upon proper nutrition. Here's how to make the most of that connection and optimize your patient's recovery.

If a wound is not healing as it should, it could be that the patient is malnourished. In the United States, approximately 40% of hospitalized patients—and 85% of patients in nursing homes—suffer from malnutrition.¹

Malnutrition might not be detected until obvious signs appear, in some cases because clinicians were not aware that their patient was at risk. One study, for example, found that nurses overestimated patients' dietary intake by 20%.²

Whether a patient's wound is the result of an injury or surgery, proper healing requires optimal nutrition. Wound healing sets off a complex chain of events that involves increased cellular activity and an intensified metabolic demand for nutrients.³ Patients who don't have enough nutrients to meet this increased demand are at risk for delayed healing, infection, longer hospital stays, and even death.¹

Although a dietitian will ultimately determine your patient's nutritional needs, you will be the first person to assess the patient's nutritional status and the condition of his wound. To promote optimal wound healing, you'll need to understand the link between nutrition and tissue repair, recognize when a patient is malnourished, and inform the rest of the healthcare team of any changes in the patient's nutritional status.

The three phases of wound healing

Before we can explore the relationship between nutrition and wound healing, it's important to briefly touch upon some wound-healing fundamentals. As you know, wound healing occurs in three overlapping stages: the inflammatory phase, the proliferative phase, and the remodeling phase.

The inflammatory phase begins at the onset of the injury and lasts up to six days.⁴ During this phase, blood vessels constrict and coagulation factors are activated, preventing additional blood loss. The coagulation cascade causes the release of leukocytes, which attack the bacteria in the wound, and monocytes, which remove dead tissue, blood clots, and bacteria from the site. Protein and clotting factors also permeate the wound.

The proliferative phase begins within seven days of the injury and lasts for two to three weeks.⁴ During this phase, new blood vessels develop, which promote the growth of granulation tissue. New tissue forms a protective covering over the wound.

Collagen, which is responsible for tissue repair, is produced by fibroblasts during the proliferative phase. The collagen and the granulation tissue grow and cross-link to form a scar.

The remodeling phase begins three weeks after the injury and is characterized by the buildup and breakdown of collagen.⁴ The wound edges are pulled inward by myofibroblasts, and scar tissue becomes softer and flattens out.

Scar tissue continues to strengthen throughout this phase, which can last for up to two years.⁴ Over time, the scar will change from red to white and reach its full tensile strength of 60% – 70% of the original tissue.

Essential to all phases of wound healing are adequate blood flow, tissue perfusion, and oxygenation.⁵ Adequate blood flow and tissue perfusion help ensure that oxygen and nutrients are delivered to the wound.

The production of collagen, for example, depends upon the availability of oxygen and protein at the wound site.⁵ As collagen develops, other components of the healing process—including white blood cell mobility, granulation tissue formation, and blood vessel development—improve as well.

Take a careful look at nutritional status

Because wound healing is so dependent upon nutrition, a comprehensive nutritional screening is critical. Begin with a diet history.⁶ Ask about the patient's daily intake, food preferences, and eating environment, including when and how he eats. A change in appetite may be the first indication of a nutrition problem. Find out if there are functional or psychological factors, such as constipation or pain, that might affect your patient's ability to eat.

Ask him if he uses nutritional supplements or herbs and if so, which ones. Also ask about drug and alcohol use. A patient who abuses alcohol, for example, is likely to have vitamin, protein, and calorie deficiencies.

Alcohol abuse is just one predictor of nutritional deficiencies. Others include a decreased serum albumin level (<3.5 gm/dL); long-term medication use; impaired immune system functioning; acute and chronic diseases, including diabetes mellitus and liver and kidney disease; and weighing less than 80% or more than 120% of the ideal body weight.⁴

Follow up the diet history with a physical assessment. Patients who are malnourished may have hair that is dull, dry, thin, or easy to pull out.⁷ They may say that their hair has lost its natural curl or changed color. You may observe yellowish lumps around a patient's eyes, redness and fissures of the eyelid corners, or white rings around both eyes.⁷

A patient who has nutritional deficiencies may have lips that are red or inflamed and cracking (cheilosis).⁷ Gums may be red, spongy, swollen, or inflamed (gingivitis) or may bleed easily. His tongue may be swollen, inflamed (glossitis), purplish, or smooth with papillae, and he might complain of a diminished sense of taste. Teeth may have gray-brown spots, and some may be missing.

Signs of a nutritional deficiency may also be evident in the patient's face. Look for paleness, scaling of the skin around the nostrils, and hyperpigmentation.⁷ You'll also want to assess the thyroid gland for enlargement.

Record your patient's weight on admission and frequently throughout his hospital stay. Weigh him on the same scale at the same time each day. Ask him what he usually weighs to determine if he has recently lost or gained weight. Remember to record his height. The most accurate way to determine height is to measure the patient while he's standing up.

Use your patient's height and weight to determine his body mass index (BMI). Divide the weight (in kilograms) by the height (in meters squared). A healthy BMI for an adult generally falls between 18.5 and 25.⁸ A BMI of 17 – 18.5 may indicate mild malnutrition; 16 – 17, moderate malnutrition; and <16, severe malnutrition.⁶

Obese patients (BMI >30) should also prompt a second look. Even with a caloric intake that's excessive, your patient may have a nutritional problem, such as a protein or vitamin C deficiency, that can impair wound healing.

Completing the picture with lab work

Your nutritional screening should also include a review of the patient's lab results. Pay particular attention to serum protein levels.⁹ The four serum proteins you should look at are albumin (normal level is 3.5 – 5.0 gm/dL), transferrin (200 – 360 mg/dL), prealbumin (16 – 40 mg/dL), and retinol-binding protein (2.6 – 7.6 mg/dL).^6,9

Low albumin levels are associated with protein deficiency, protein-losing gastrointestinal disease, and acute metabolic stress.⁹ However, because the half-life of albumin is 20 days, a patient may become malnourished before a decrease in serum albumin is noted.

Serum transferrin has a half-life of eight to 10 days and its levels respond quickly to changes in protein intake. It is, therefore, a more sensitive indicator of protein deficiency than albumin. Levels below 200 mg/dL indicate that protein stores are becoming depleted.⁹

Prealbumin has a half-life of two to three days, so it's a very sensitive indicator of a patient's protein status. Prealbumin levels will decrease rapidly when a patient is underfed for even a brief period, and they will increase rapidly with dietary support. Levels of <16 mg/dL are associated with malnutrition.⁶ Retinol-binding protein has a half-life of approximately 12 hours; levels of <2.6 mg/dL reflect a protein deficiency.⁹

Serum protein levels, however, are just one indicator that the patient's nutritional status is not optimal for wound healing. The results of two less commonly performed immune system function tests can also identify nutritional roadblocks.

The first is the total lymphocyte count. If it is lower than 15,000 cells/mm³, the patient may have a moderate protein deficiency. The second test is the skin antigen test, or anergy panel, in which the patient is given antigens subcutaneously. The inability to respond to the antigens—in the form of a rash—may be related to a nutritional deficiency.¹⁰

Feeding your patient to help him heal

To avoid malnutrition and wound complications, patients need adequate calories, protein, and fluid. Based on input from your history and physical assessment, a dietitian will determine the amounts of carbohydrates, protein, fat, vitamins, and minerals that your patient will need for wound healing. (For more information on how these nutrients promote healing, see the "Nutrients provide fuel for healing" box.)

Calories are needed to supply the energy necessary for wound healing. As a general rule, an adult critical care patient needs 25 – 30 calories per kilogram of body weight per day.⁴ Patients with wounds also need adequate protein—1.5 – 3 gm/kg per day, depending upon the severity of the wound and other factors.⁵

Water is essential for cells to function normally. Water balance, or hydration, is present when a patient's fluid intake equals his output. Dehydration occurs when a patient doesn't receive enough fluid, or when fluid loss exceeds intake. (Wound drainage can be a source of fluid loss.) Dehydration reduces blood volume, which further decreases circulation and reduces oxygen and nutrient delivery to the tissues.⁹ To help ensure that a patient is properly hydrated, 30 – 35 ml of fluid per kg of body weight per day may be adequate unless contraindicated.⁹

Your patient may require tube feeding

A patient can meet his nutritional requirements orally by eating a balanced diet and, if necessary, taking supplements. Patients who are unable to consume at least half of their required calories and protein on their own may need enteral or parenteral nutritional support.⁴ A general rule of thumb is that oral feeding is better than enteral feeding, which is better than parenteral feeding.¹¹

Clinicians consider many factors when determining which feeding route is best for a patient, including the patient's current feeding route, the medications he's receiving, and the procedures he'll undergo.¹⁰ Other factors to consider include:¹⁰

• Is the patient unconscious, mechanically ventilated, or otherwise unable to eat safely?

• Does the patient have a hard abdomen or an absence of bowel sounds, which could indicate an obstruction or other problem that might preclude enteral feeding?

• Does the patient have bed restrictions that might increase his likelihood of aspiration?

• Does the patient have injuries to specific tissues or organs that would affect his ability to consume and digest food?

• What are the future medical or surgical plans for the patient, and how long will nutritional support be required?

• Is the patient's skin otherwise intact? Are there draining wounds, fistulas, or pressure sores?

Enteral tube feeding is indicated when a patient with a functioning GI tract can't consume the amount or type of nutrients needed by mouth. For example, a patient may require enteral feeding because he's mechanically ventilated or at risk for aspiration because of altered consciousness, or he has a diminished gag or cough reflex.

One benefit of enteral feeding is that it promotes blood flow to the gut and helps maintain mucosal integrity.¹¹ If a patient will need enteral feeding for less than four weeks, a nasogastric, nasoduodenal, or nasojejunal route should be considered. If long-term feeding is necessary, a gastrostomy or jejunostomy tube can be inserted surgically. Conditions such as facial fractures or CNS trauma may also dictate the route used.^2,10

Currently, more than 100 enteral formulas are available. There are "standard" formulas that provide the recommended daily intake of vitamins and minerals, formulas designed to strengthen a patient's immune system, ones that contain fiber, and specialty formulas for patients with a specific disease or condition.

Several formulas are promoted as enhancing wound healing, including Boost HP, Crucial, Isosource, and Promote. These formulas provide higher levels of protein, vitamins (usually A and C), zinc, and sometimes arginine. However, patients with a wound who also have other conditions such as diabetes, pulmonary disease, or impaired liver or kidney function wouldn't receive one of these wound-healing formulas. Instead, they would receive a formula designed specifically for their particular condition.

If your patient is receiving enteral feeding, check tube placement regularly. Also assess the tube's exit site for redness, swelling, skin breakdown, warmth, and drainage.

Irrigating the tube frequently according to your facility's guidelines helps maintain its patency. Determine how well your patient is tolerating the feeding by assessing for bowel sounds, flatus, stools, residuals, and discomfort from distention, nausea, vomiting, or diarrhea.

When parenteral feeding is necessary

Patients who can't tolerate enteral feeding will need parenteral nutrition. Peripheral parenteral nutrition (PPN) is used for short-term therapy—up to seven days. Total parenteral nutrition (TPN), which requires a central line, is indicated when parenteral feeding will be needed for longer than a week.

Each bag of TPN contains glucose, amino acids, electrolytes, vitamins, trace elements, a histamine blocker, and insulin as needed. Lipids are sometimes infused separately and are especially useful for patients who have fluid restrictions.

A patient who'll be receiving TPN should have blood tests to establish baseline levels of phosphorus, magnesium, triglycerides, and electrolytes. After that, monitor the patient's glucose levels regularly, and watch for hyperglycemia.

The central line used to administer TPN raises a patient's risk of infection, so check the patient for signs and symptoms of catheter-related infection. A patient who shows signs of infection should have a fever workup, which may include blood cultures. If you suspect that your patient has central line sepsis, the line should be replaced.¹⁰

Whether your patient's nutritional needs are complex or relatively straightforward, your attention to the details will serve him well. Appropriate nutritional support can help patients avoid malnutrition, delayed healing, and complications such as infection or sepsis. And in the end, that will help improve his chances of a successful recovery.

REFERENCES

1. Williams L. (2002). Assessing patients' nutritional needs in the wound-healing process. J Wound Care, 11(6), 225.

2. Ferguson, M., Cook, A., et al. (2000). Pressure ulcer management: The importance of nutrition. Medsurg Nurs, 9(4), 163.

3. MacKay, D., & Miller, A. L. (2003). Nutritional support for wound healing. Altern Med Rev, 8(4), 359.

4. Kiy, A. M. (1997). Nutrition in wound healing: A bio-psychosocial perspective. Nurs Clin North Am, 32(4), 849.

5. Whitney, J., & Heitkemper, M. (1999). Modifying perfusion, nutrition and stress to promote wound healing in patients with acute wounds. Heart Lung, 28(2), 123.

6. Huckleberry, Y. (2004). Nutritional support and the surgical patient. Am J Health Syst Pharm, 61(7), 671.

7. Ayello, E. A., Thomas, D. R., & Litchford, M. A. (1999). Nutritional aspects of wound healing. Home Healthc Nurse, 17(11), 719.

8. U.S. National Library of Medicine, National Institutes of Health. "Body mass index." 2003. www.nlm.nih.gov/medlineplus/ency/article/007196.htm (25 May 2004).

9. Leininger, S. M. (2002). The role of nutrition in wound healing. Crit Care Nurs Q, 25(1), 13.

10. McQuillan, K. A. (Ed). (2002). Trauma nursing: From resuscitation through rehabilitation (3rd ed.). Philadelphia: W. B. Saunders.

11. Cheever, K. H. (1999). Early enteral feeding of patients with multiple traumas. Crit Care Nurse, 19(6), 40.

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Nutrients provide fuel for healing

For a wound to heal successfully, patients need adequate amounts of nutrients, including carbohydrates, protein, fat, vitamins, and minerals. Those who don't meet their nutritional needs are at risk for delayed wound healing and other wound-related complications. A dietitian will determine how much of each nutrient your patient needs.

Carbohydrates are needed for energy. An adult's carbohydrate intake should account for 45% ­ 60% of total consumed calories; less than that may lead to the breakdown of protein stores. The main carbohydrate is glucose, which is necessary for cellular growth, fibroblastic mobility, and leukocyte activity.

Protein is necessary for tissue repair and maintenance. The recommended daily allowance of protein is 0.8 gm/kg of body weight per day; a patient with a wound will need 1.5 ­ 3 gm/kg per day, depending upon the severity of the wound and other factors. Insufficient protein intake inhibits collagen and fibroblast production, impairing wound healing. However, taking in too much protein increases protein synthesis, which puts a burden on the kidneys and liver and can lead to dehydration.

Fat is a concentrated source of energy. It is essential for digestion, absorption, and transport of the fat-soluble vitamins (A, D, and E). Fat should account for approximately 20% of calorie intake.

Vitamins A and C are also essential for wound healing. Vitamin A is lipid-soluble and stored in the liver. It is necessary for the early inflammatory phase of wound healing, for wound debridement, and for scar tissue strengthening. Vitamin A can prevent the delay in wound healing that steroids often cause. A deficiency decreases collagen and granulation tissue development and increases the likelihood of wound infection. High doses of vitamin A, however, can be toxic.

Vitamin C supports collagen synthesis. It's water-soluble; the body can't store it. A patient who's deficient in vitamin C may have bleeding gums or small red spots (petechiae) around the hair follicles, and may bruise easily and heal slowly. When supplementation is necessary, the dosage should be 100 ­ 300 mg a day. There's no evidence that vitamin C accelerates wound healing in patients who don't have a deficiency.

Another requirement for wound healing is zinc. It supports collagen development, cell division, and protein synthesis. A deficiency can lead to abnormalities in white blood cell function, increasing the risk of wound infection. Supplementation typically consists of 15 ­ 30 mg a day. Too much zinc, however, can impair wound healing and cause GI distress. Other minerals&#151;namely, copper, iron, and manganese&#151;reportedly help with tissue regeneration, but deficiencies of these minerals have not been linked to impaired wound healing.

Sources: 1. Leininger, S. M. (2002). The role of nutrition in wound healing. Crit Care Nurs Q, 25(1), 13. 2. Kiy, A. (1997). Nutrition in wound healing: A bio-psychosocial perspective. Nurs Clin North Am, 32(4), 849. 3. MacKay, D., & Miller, A. L. (2003). Nutritional support for wound healing. Altern Med Rev, 8(4), 359.