Nutrition 411: Avoiding Dehydration in Patients With Wounds
If you work in long-term care, you are probably familiar with the federal regulation requiring the provision of sufficient fluids to each patient, otherwise known as F327.
This daily physiologic requirement doesn’t get as much attention outside of long-term care. Proper hydration deserves a closer look for several reasons, especially in patients with pressure ulcers and other types of chronic wounds. Hydration status affects blood volume, blood circulation, and skin turgor, which are all important issues in the wound healing process. Patients with heavily draining wounds, infections, or fever may need additional fluids. Also, the use of an air-fluidized mattress causes water evaporation and increases the fluids required for that patient. This article reviews the basic functions of water, identifies risk factors and symptoms of dehydration, and provides guidelines on how to meet each patient’s daily needs.
Functions of Water
Water performs many essential functions in the human body. One of the primary functions is to provide turgor or fullness to the body’s tissues. In other words, water gives us shape by exerting fluid pressure on the cell membranes. Women are approximately 50% to 55% water; men are approximately 55% to 65% water.1 The higher water content in most men is due to their higher muscle content. Water makes up about three fourths of the weight of lean tissue and less than one fourth of the weight of fat. For example, a man weighing 165 pounds is carrying approximately 90–107 lb of water.
Water serves as the medium for all life-supporting chemical reactions in our body; it is the necessary chemical solvent on which various body tissue solutions are based. Water also maintains stable body temperature. Depending on the climate, the skin will adjust its water loss in order to maintain an acceptable body temperature. As perspiration is evaporated, the body is cooled. Water is also important in maintaining blood volume, carrying nutrients and waste products throughout the body, and acting as a lubricant and cushion around joints and other area of the body such as inside the eyes.2
Dehydration Risk Factors and Symptoms
The primary safeguard against dehydration is the thirst mechanism. Thirst occurs as a result of even small fluid losses. As we age, the thirst mechanism becomes less sensitive, and many elderly and infirm patients many not even recognize thirst due to altered cognition or sensory impairments. Other risk factors for dehydration include diarrhea, vomiting, fever, functional impairments such as not being able to hold a drinking cup, urinary tract infections, internal bleeding, renal impairment, and swallowing disorders. Depending on mobility issues and level of independence, some patients deliberately limit fluid intake in order to minimize urination because of the assistance required to get to the bathroom and a fear of incontinence. Air-fluidized mattresses pose an additional risk factor because the heat they generate increases moisture evaporation from the skin. When a patient is assessed as having one or more risk factors for dehydration, it is important to be able to recognize the symptoms of dehydration and have an action plan. Table 1 outlines the common symptoms of dehydration.
A diagnosis of dehydration is frequently based upon clinical signs and symptoms. Laboratory testing is typically not required for mild to moderate dehydration; however, in cases of severe dehydration, laboratory testing is typically ordered to identify electrolyte and acid-base imbalances, evaluate kidney function, and assess general health status. These tests usually start with a basic metabolic profile (BMP) and complete blood count (CBC). The BMP will report the electrolytes (sodium, potassium, chloride, bicarbonate), blood urea nitrogen, and creatinine to evaluate renal function. Additional tests can be ordered depending on the diagnoses of the specific patient. Depending on the results, dehydration can be classified as one of three types:
• isotonic dehydration: a balanced depletion of water and sodium often caused by diarrhea and vomiting or significant blood loss;
• hypotonic dehydration: a 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;
• hypertonic dehydration: a depletion of fluid losses exceeding sodium losses.
Estimating Fluid Needs
It is often said we need to drink 8 glasses of water daily. Although this is a good sound bite, a more precise estimate of fluid needs is required because each patient has a unique medical situation. According to the National Research Council,3 it is impossible to set a general water requirement. This is because the requirement is the amount necessary to balance the insensible losses (which can vary markedly from person to person) and maintain a tolerable solute load for the kidneys (which may vary with dietary composition and other factors). For practical purposes, 1 mL/kcal of energy expenditure can be recommended as the water requirement for adults under average conditions of energy expenditure and environmental exposure. The recommendation may be increased to 1.5 mL/kcal to cover variations in activity level, sweating, and solute load.3 Common practice for registered dietitians (RDs) is to interpret this as meaning 1 mL of fluid is required for each calorie of estimated needs. For example, if a patient is estimated to require 1,800 calories/day, that patient also requires 1,800 mL of fluid/day to keep the 1-to-1 ratio.
A second method RDs often use is to estimate fluid needs based on body weight. For patients with normal fluid status, 30 mL/kg of body weight is recommended. The estimate may range from 25–35 mL/kg of body weight depending on the clinical condition of the individual. For example, a patient with (congestive) heart failure would be at the lower end (near 25 mL/kg), while a dehydrated patient or one with heavily draining wounds would be at the higher end of the range.4 It is important to note the minimum recommendation regardless of calorie intake or weight is 1,500 mL/day.5 Table 2 summarizes different methods of estimation.
The prevention and treatment of dehydration should be a priority for all health care practitioners (HCPs) when treating patients with wounds. Most patients do not meet with an RD unless a severe nutritional problem is noted, so monitoring is up to the entire multidisciplinary team. Dehydration can begin in only a few hours, making it important to be vigilant for the warning signs. HCPs should be trained to have a heightened awareness of dehydration, especially in the warmer months.
Most intervention plans focus on providing a wide array of beverage choices at frequent intervals throughout the day. Although water is always a good choice, fluids also may include juice, milk, ice chips, fruit ices, sorbets, soups, gelatins, ice cream, and oral nutrition supplements such as Ensure® (Abbott Nutrition, Columbus, OH). Foods with a high water content also may contribute to the overall daily fluid intake. Fruits and vegetables have the highest water content of the various food groups. Table 3 lists the water content of some common foods for comparison. Caffeinated and alcoholic beverages should be limited because they have a diuretic effect. However, in moderation, they may be acceptable if this is what the patient desires. Table 4 lists strategies that may be used to combat dehydration. For patients with physical problems, various types of adaptive equipment may be utilized to promote hydration independence. These include cups with handles, nonskid bases, angled mouthpieces, and/or leakproof lids. Companies manufacture special cups for patients post-stroke or persons with dysphagia that deliver “small swallows” to minimize the risk of aspiration.
Dehydration is an important issue because water is vital to basic survival. A person can survive weeks without food but only days without water. Rather than manage this problem begrudgingly, have fun with fluids! Health care facilities can develop a signature beverage, sponsor beverage recipe contests, decorate water pitchers, and add more variety to available beverage selections including “mocktails” and toast to good health and wound closure.
Nancy Collins, PhD, RDN, LD, FAPWCA, FAND is a registered dietitian and founder/clinical editor of Nutrition411.com. For the past 25 years, she has served as a consultant to health care institutions and is a medico-legal expert for law firms involved in health care litigation. Correspondence may be sent to Dr. Collins at NCtheRD@aol.com. This article was not subject to the Ostomy Wound Management peer-review process.
1. Niedert KC, Dorner B. Nutrition Care of the Older Adult, 2nd ed. Chicago, IL: American Dietetic Association;2004:197.
2. US National Library of Medicine & NIH. MedlinePlus Medical Encyclopedia: Water in Diet. Available at: www.nlm.nih.gov/medlineplus/ency/article/002471.htm. Accessed January 16, 2015.
3. National Research Council. Recommended Dietary Allowances. National Academies Press, 10th ed. 1989. Available at: www.nap.edu/openbook.php?record_id=1349&page=249. Accessed January 16, 2015.
4. Allen SD. Nutrition Concepts and Medical Nutrition Therapy. St. Charles, IL: Association of Nutrition and Foodservice Professionals;2012:249.