Hydration and Dehydration in Older Adults

Hydration is the chemical combination of a substance with water, the addition of water to a substance or tissue (Taber’s Cyclopedic Medical Dictionary, 1997, p. 920). Water is essential to sustain all cellular function (Chernoff, 1999). The percentage of water in older adults is approximately 60%. Clinicians contend that by promoting sufficient quantity and quality of fluids, especially water, fluid balance will more likely be achieved. Dehydration is the rapid weight loss of greater than 3% of body weight (Weinberg, A. D., & Minaker, 1995, p. 1553). 

Clinical symptoms of dehydration may be absent in older adults, until the condition warrants immediate hospitalization and intravenous replacement flu-ids (Weinberg & Minaker). Symptoms include change in mental status, confusion, lethargy, tachycardia, and syncope. Assessing skin turgor and dry mouth, a diagnostic marker of dehydration in middle-aged adults, is unreliable for detection of dehydration in older adults because of common age-related changes. Skin turgor may already be poor because of decreased subcutaneous tissue, while dry mouth may be due to mouth breathing or lack of oral care.

Dehydration in Older Adults

Dehydration is one of the top 10 reasons for hospitalization of older adults (Centers for Disease Control [CDC], 2002). In 1996, the hospitalization of older people with the primary diagnosis of dehydration cost $1.36 billion Medicare dollars (Burger, Kayser-Jones, & Bell, 2000). Older adults with a primary hospital admission diagnosis of dehydration are three times more likely to die within 30 days of admission compared to those with a primary admission diagnosis of a hip fracture (CDC). Managing hydration status to increase oral fluid intake in older people may reduce the number of hospitalizations and deaths associated with dehydration (Burger, Kayser-Jones, & Bell).
The prevalence of dehydration in the nursing home is not easily tracked, but it is thought to be significantly higher than among community-dwellers because of nursing home residents’ comorbidites, polypharmacy, declining functional and cognitive status, insufficient oral fluid intake (OFI), and dependence on scarce staff and the institutional food delivery system. Estimated prevalence of dehydration among Skilled Nursing Facility (SNF) residents is 35% or higher (Weinberg & Minaker, 1995). Of those SNF residents with dehydration, mortality rates are as high as 50% (Wakefield, Mentes, Diggelmann, &Culp, 2002). Yet, in many cases, dehydration of nursing home residents is reversible and preventable.
Across all settings, older adults are at risk for insufficient hydration and for dehydration for the following major reasons:
1. Older adults sustain lower baseline TBW (total body water). Episodic ill-nesses such as diarrhea, nausea accompanied by vomiting, and fever result in even lower TBW. Depletion of as little as 1 to 2 liters of water can create a state of dehydration in an older adult. Infants and young children dehydrate for the same reason—lower baseline TBW. With decreased TBW, hypernatremia or hyponatremia become a potential electrolyte problem.
2. Thirst response is diminished in older adults. As TBW drops below 1 liter, older adults may not experience thirst as a prompt to drink fluids due to changes in baroreceptors, decreases in vasopressin, and antidiuretic hormone (ADH) (Phillips, P. A., et al., 1984).
3. Decreased reserve capacity, especially in renal function and creatinine clearance, and slower response to illness and stressors create a more delicate homeostatic balance. Thus, it takes a lesser body stressor to fuel a crisis in an older adult than would be necessary to similarly affect a middle-aged adult. The older adult’s ability to recover is also extended beyond that which would be expected in a middle aged adult.
4. Older adults limit their fluid intake for convenience, especially if incontinence is present (Gaspar, 1999). For some individuals, the embarrassment of incontinence may outweigh the health benefit of drinking water or other fluids. In addition, disease states, such as diabetes or congestive heart failure, could place the older adult’s fluid balance at risk for imbalance (Weinberg & Minaker, 1995).
Preventively, evaluating OFI and laboratory values over time may be useful in detecting insufficient hydration in older adults. Older people generally fail to drink sufficient amounts of fluids. The recommended older adult OFI is a minimum of 1.5 L of liquid over 24 hours (Chernoff, 1999). Thirty milliliters per kilogram of body weight has also been used as a parameter to estimate the adequacy of daily fluid intake (Chernoff). Laboratory tests include: blood urea nitrogen/creatinine ratio (BUN/Cr), sodium, plasma specific gravity, and serum osmolality (Weinberg & Minaker, 1995). Bioelectric impedance analysis (BIA), a noninvasive method using electrodes to measure body compartments including intracellular, extracellular, and TBW, has been used to detect fluid balance (Chumlea & Guo, 1994; Robinson, S. B., & Rosher, 2002). Urine color charts have also been used and show correlation with some laboratory tests (Wakefield et al., 2002). Yet further research needs to be conducted to study sensitivity and specificity of tests to detect varying degrees of hydration status, from adequate hydration to mildmoderate-acute dehydration.
Prevention of dehydration in the most vulnerable group—nursing home residents—needs to be studied empirically. Two recent evidence-based studies provide findings to support specific effective protocols. S. F. Simmons, Alessi, and Schnelle (2001) tested a three-phase 8-month intervention on 63 nursing home residents. They used three behavioral approaches to improve residents’ hydration status: (a) prompting (four times/day for 16 weeks), (b) increased prompting (eight times/day for 8 weeks), and (c) increased prompting plus offering choice of beverage each day for 8 weeks. Eighty-eight percent of the sample was mildly or moderately dehydrated at baseline. OFI, serum osmolality, and BUN/cr ratio laboratory tests were measured before, during, and after each phase of the intervention. Eighty-one percent of the intervention group showed significant increases in between-meal oral fluid intake (OFI). Serum osmolality and BUN/Cr ratios in dehydrated residents significantly improved compared with the control group. A behavioral approach that combines consistent and frequent prompting and giving nursing home residents choices of beverage can support an effective hydration program which may improve hydration status.
Robinson and Rosher (2002) demonstrated that using a beverage cart in nursing home residents (N = 51) improved OFI and was associated with reduced use of laxatives, improved bowel function, and fewer falls. They based their hydration program on suggestions of Zembrzuski (1997) and T. Welch (1998) to use beverage carts, provide appealing fluids, offer choice of beverage, and use containers with visual appeal. Four types of between-meal fluids were displayed on a beverage cart along with colorful glassware and seasonal decorations.
Nursing home residents were assisted by two hired Certified Nurses Aides (CNAs) to consume an additional 480 cc daily over 5 weeks. Use of BIA showed that at the end of the intervention, the residents’ TBW increased significantly (p= .001), laxative use decreased significantly (p = .05), falls declined (p = .05), and number of bowel movements increased (p = .04). Robinson and Rosher concluded by recommending beverage cart service at mid-morning and mid-afternoon. Application of this research suggests that offering 480 cc total of between meal fluids to nursing home residents can make a clinical as well as statistically significant difference in their hydration status. Increasing OFI of older adults can prevent dehydration and unnecessary hospitalizations. Assessment and early-detection screening tools and empirically supported hydration programs are needed.