Dehydration and Wound Healing: Know The Facts

By Mary Ellen Posthauer RDN, CD, LD, FAND

In addition to providing calories and protein to promote wound healing, fluid intake is equally important. Achieving hydration needs and preventing dehydration, a risk factor for pressure ulcer development due to its effect on blood volume and skin turgor, is vital.

Fluids are needed for oxygen profusion, hydration to the wound bed, as the transport medium for nutrients, as a solvent for vitamins, minerals, glucose, amino acids, and to transport waste away from the cells.

Dehydration is defined as a rapid loss of 3% or more of body weight that is associated with water and electrolyte disturbance from either water or sodium depletion. Symptoms of dehydration include; changes in weight (3%-5% in < 30 days), decreased/concentrated urine output, dry or tenting skin, altered mental status (especially in the elderly) or elevated serum sodium levels, BUN (blood urea nitrogen), or hematocrit levels.

The three classifications of dehydration:

• Isotonic dehydration is classified as a balanced depletion of water and sodium caused by diarrhea and vomiting.
• Hypertonic dehydration is depletion of total body weight (TBW) due to diminished water intake, pathologic fluid loss or both.
• Hypotonic dehydration is depletion of water and sodium but sodium loss predominates, resulting in extracellular fluid loss. Hypotonic dehydration may be a result of diuretics, renal disease or decreased intake of sodium and water.

Around 60% of total body weight (TBW) for healthy young adults is located in the intracellular and extracellular compartments. TBW declines with age and older adults have additional risk factors for dehydration including decreased thirst perception, declining ability to concentrate urine, as well as multiple medications that alter electrolyte imbalance, such as diuretics. Cognitive or functional impairments increase older adults’ dependence on others for assistance at meals. Fluid needs are increased when an individual has fever, diarrhea, profuse sweating (resulting in frequent linen changes), draining wounds, or is on a support surface that elevates body temperature. Since individuals with CHF or renal failure may not be able to tolerate additional fluids, the registered dietitian must work with the wound care team to determine appropriate fluid levels.

Several formulas are used to calculate an individual’s fluid requirements. One formula utilizes 30-mL/kg body weight and another utilizes 1 mL/kilocalorie consumed. Water sources include fluids, the water content of food (19-28% in a healthy hydrated individual) and the small amount produced by oxidation of food. Some foods become fluids at room temperature such as ice cream, sherbets, or gelatin. Most oral nutritional supplements and enteral feeding contain approximately 75% free water, but note that the high calorie products with 1.5 or 2 kilocalories per mL have less free water. The product label or information will indicate the amount of free water.

Every member of the wound care team has a responsibility to prevent dehydration by offering fluids throughout the day and not just at mealtime. Offer water or other fluids after turning an individual, or 4oz of fluid with medications. Remember that every sip counts. Educate the individual and/or caregiver on the importance of adequate hydration for wound healing. Does the therapy room have water or additional fluids available? Water bottles or travel mugs can be attached to wheelchairs for easy access. Are there hydration stations available such as self-serve juice or beverage machines? Does the individual in bed have easy access to their water pitchers? Does the menu offer a variety of beverages selections such as carbonated beverages, juices, flavored water, coffees or teas?

By recognizing the danger signs for dehydration, developing an interdisciplinary treatment program and monitoring the outcome, we can all better help our patients on their path to recovery.

About The Author
Mary Ellen Posthauer RDN, CD, LD, FAND is an award winning dietitian, consultant for MEP Healthcare Dietary Services, published author, and member of the Purdue University Hall of Fame, Department of Foods and Nutrition, having held positions on numerous boards and panels including the National Pressure Ulcer Panel and the American Dietetic Association’s Unintentional Weight Loss work group.

The views and opinions expressed in this blog are solely those of the author, and do not represent the views of WoundSource, Kestrel Health Information, Inc., its affiliates, or subsidiary companies.