CHAPTER

The importance of maintaining fluid homeostasis for older adults is well known (1). Yet water and other fluids that need to be consumed often do not receive the attention needed. In some older adults, as little as 500 mL of fluid can make the difference between fluid deficit and fluid overload (2). Dehydration, a form of malnutrition, is a major problem in older adults, espe- cially persons older than 85 and institutionalized older adults (3). It is documented that adults over 85 have a higher prevalence of dehydration than those under 65 (2). An early report cited dehydration as the most common fluid and electrolyte disorder among older nursing facility residents, at nearly 60% (4,5). Another early report claimed that more than half of patients hospitalized with a diagnosis of dehydration came from nursing homes (6). There are few data available about the prevalence of dehydration today. Implementation of the Resident Assessment Instrument (RAI) in 1993 was associated with a significant decline in prevalence, compared with prevalence in 1990 (7). Still, the problem of dehydration persists. In 2010, dehydration was listed as one of the reported diagnoses in 1,225,000 hospitalizations (8). The 2010 National Hospital Discharge Survey showed that 149,000 people aged 65 and older were discharged in 2010 with a primary diagnosis of volume depletion (9). Studies demonstrate that older residents rou- tinely do not consume enough fluid (10-12). In one study, researchers found that only 1 in 40 older resi- dents consumed an adequate amount of liquids (10). There is some evidence that chronic mild dehydra- tion may be a common condition in some population groups, especially elderly individuals (13,14). Both acute and chronic dehydration carry an increased risk of morbidity and mortality, especially for vulnerable older individuals. Because of the negative outcomes associated with dehydration, health care professionals must carefully assess hydration status, estimate fluid

8

Implications of Abnormal Hydration Status

needs, and ensure that the older adult gets adequate and appropriate fluids.

NORMAL HYDRATION STATUS AND

DEHYDRATION Normal hydration status refers to the state in which the body has sufficient water in the right locations and con- taining the right ratios and amounts of electrolytes (for example, sodium and potassium) (2). Dehydration occurs when the body loses more water than is taken in or replaced (2). Because no uni- versally accepted definition of dehydration exists, several parameters have been used to suspect or define this condition. However, all of these definitions have limitations (15). This confusion over the definition of dehydration results in difficulty diagnosing dehydration in the long-term care (LTC) setting. Dehydration may be inappropriately used as a nonspecific term referring to derangement in any fluid compartment. Furthermore, a diagnosis of dehydration may be inappropriately used as a medical reason for hospitalization when, in fact, at the time of admission these patients do not truly meet any accepted diagnostic criteria.

Dehydration is often accompanied by disturbances

in the body’s mineral salt or electrolyte balance, espe- cially those in the concentrations of sodium and potas- sium. Under typical circumstances, the body loses about 2,500 mL of water every day from perspiration (650 mL), pulmonary evaporation/respiration (450 mL), stool (100 mL), and urine (1,300 mL). “If water is lost from the bloodstream, the body can compensate somewhat by shifting water from cells into the blood vessels, but this is a very short-term solution. If the lost water is not replenished, the body may suffer serious consequences” (16). Box 8.1 provides examples of consequences of dehydration. Volume depletion is a reduction in extracellular fluid volume that occurs when salt and fluid losses exceed intake on a sustained basis (17). This may result