Managing Oral Hydration   9  

Janet C. Mentes

OVERVIEW

Studies using biomarkers (serum sodium, osmolality, and blood urea nitrogen [BUN]/creatinine ratio) for dehydration and volume depletion from the Established Populations for Epidemiologic Studies of the Elderly (EPESE; Stookey, Pieper, & Cohen, 2005) and National Health and Nutrition Examination Survey III (NHANES III; Stookey, 2005) found that the prevalence rate for these conditions in community-dwelling older adults could range from 0.5% to 60% depending on the markers used. Another study found that 48% of older adults presenting with dehydration at an emergency room (ER) unit were from the community (Bennett, Thomas, & Riegel, 2004) and, more recent, El-Sharkawy, Shahota, Maughan, and Lobo (2014) found that 40% of older adults were dehydrated on admission to a hospital and 44% were found to be dehydrated at 48 hours. Maintaining adequate fluid balance is an essential component of health across the life span; older adults are more vulnerable to shifts in water balance—both overhydration and dehydration—because of age-related changes and increased likelihood that an older individual has several medical conditions (Hooper, Bunn, Jimoh, & Fairweather-Tait, 2013). Dehydration is the more frequent occurrence in older adults (Warren et al., 1994; Xiao, Barber, & Campbell, 2004). In fact, avoidable hospitalizations for dehydration in older adults have increased by 40% from 1990 to 2000, at a cost of $1.14 billion (Xiao et al., 2004), and is one of the Agency for Healthcare Research and Quality’s 13 ambulatory care-sensitive conditions. When dehydration is considered as a comorbid condition the cost of hospitalizations and rehospitalizations is even higher (Frangeskou, Lopez-Valcarcel, & Serra-Majem, 2014).

Careful attention to hydration requirements of older adults will not only help prevent hospitalizations for dehydration but also decrease associated conditions such as acute confusion and delirium (Foreman, 1989; Mentes & Culp, 2003; Mentes, Culp, Maas, & Rantz, 1999; O’Keeffe & Lavan, 1996; Seymour, Henschke, Cape, & Campbell, 1980), adverse drug reactions (Doucet et al., 2002), infections (Beaujean et al., 1997; Masotti et al., 2000), increased morbidity associated with bladder cancer (Michaud et al., 1999), coronary heart disease (Chan, Knutsen, Blix, Lee, & Fraser, 2002; Rasouli, Kiasari, & Arab, 2008), stroke (Lin, Lee, Hung, Chang, & Yang, 2014; Rodriguez et al., 2009), and other thromboembolytic events (Kelly et al., 2004). Furthermore, dehydration has been associated with longer hospital stays for rehabilitation (Frangeskou et al., 2014; Mukand, Cai, Zielinski, Danish, & Berman, 2003) and for readmission to the hospital (Frangeskou et al., 2014; Gordon, An, Hayward, & Williams, 1998). Even in healthy community-dwelling older adults, physical performance and cognitive processing is affected by mild dehydration (Ainslie et al., 2002).

Oral hydration of older adults is particularly complex for a variety of reasons. In the following review, issues of age-related changes, risk factors, assessment measures, and nursing strategies for effective interventions for dehydration are addressed.

BACKGROUND AND STATEMENT OF PROBLEM

Water is an essential component of body composition. Intricate cellular functions, such as gene expression, protein synthesis, and uptake and metabolism of nutrients, are affected by hydration status. Organ systems, specifically the cardiovascular and renal systems, are particularly vulnerable to fluctuating levels of hydration (Metheny, 2000).

Older individuals are at increased risk for hydration problems stemming from several converging age-related factors, including lack of thirst (Ainslie et al., 2002; Phillips, Bretherton, Johnston, & Gray, 1991; Phillips et al., 1984); changes in body composition, specifically loss of fluid-rich muscle tissue (Bossingham, Carnell, & Campbell, 2005); increasing inability to respond efficiently to physiological stressful events through which dehydration results (Farrell et al., 2008; Rolls, 1998); and renal changes, including a reduced renal capacity to handle water and sodium efficiently (Macias-Nuñez, 2008). Additionally, personal, often lifetime hydration habits, may contribute to risk but have not been explored in relation to underhydration. As a result, older adults are often at risk for a chronic state of underhydration. Several studies (Bossingham et al., 2005; Morgan, Masterson, Fahlman, Topp, & Boardley, 2003; Raman et al., 2004) of community-dwelling older adults suggest that under normal conditions, older adults maintain adequate hydration; however, when challenged by environmental stressors—physical or emotional illness, surgery, or trauma—they are at increased risk for dehydration and rapidly become dehydrated if they are already chronically underhydrated.

DEFINITIONS

Dehydration

Dehydration is the depletion in total body water (TBW) content caused by pathological fluid losses, diminished water intake, or a combination of both. It results in hypernatremia (more than 145 mEq/L) in the extracellular fluid compartment, which draws water from the intracellular fluids. The water loss is shared by all body-fluid compartments and relatively little reduction in extracellular fluids occurs. Thus, circulation is not compromised unless the loss is very large.

Underhydration

Underhydration is a precursor condition to dehydration associated with insidious onset and poor outcomes (Mentes, 2006; Mentes & Culp, 2003). Others have referred to this condition as mild dehydration (Stookey et al., 2005), chronic dehydration (Bennett et al., 2004), or impending water loss dehydration (Hooper et al., 2011).

ASSESSMENT OF THE PROBLEM

Assessment of the hydration status consists of determining adequate intake, risk identification with attention to specific populations at increased risk, assessment of hydration habits, and evaluation of specific biochemical and clinical indicators.

Determining Adequate Intake

All older adults should have an individualized fluid goal determined by a documented standard for daily fluid intake. There are many standards that have been developed (Table 9.1). However, Gaspar (2011) has compared four standards and has produced a nomogram based on an individual’s weight and height, which is the most individualized standard. Table 9.1 provides examples of daily fluid goal calculations.

Risk Identification

Risk for dehydration in ill or frail older adults across care settings has been studied more frequently. Although there is no outstanding risk factor for dehydration, age, gender, ethnicity, class, and number of medications taken, level of activities of daily living (ADL) dependency, presence of cognitive impairment, presence of medical conditions such as infectious processes, and a prior history of dehydration have all been associated with dehydration in older adults (Mentes & Iowa–Veterans Affairs Nursing Research Consortium [IVANRC], 2000). Therefore, although single risk factors are discussed, it is likely that clusters of risk factors may be more helpful in clinical settings (Leibovitz et al., 2007).

TABLE 9.1

Daily Fluid Goal Formulas

BW, body weight.

Increasing age is associated with increased likelihood of dehydration (Ciccone, Allegra, Cochrane, Cody, & Roche, 1998; Lavizzo-Mourey, Johnson, & Stolley, 1988; Warren et al., 1994). Ciccone et al. (1998) found that adults aged 85 years and older were three times more likely to have a diagnosis of dehydration on admission to an emergency department than adults aged 65 to 74 years. Older African American and Black adults have higher prevalence rates of dehydration on hospitalization than Caucasian adults (Lancaster, Smiciklas-Wright, Heller, Ahern, & Jensen, 2003; Warren et al., 1994). Female gender has been associated with risk for dehydration in nursing home residents (Lavizzo-Mourey et al., 1988); however, male hospitalized patients had an increased risk for dehydration (Warren et al., 1994) and, more recent, no gender differences were detected in a large database study (Xiao et al., 2004).

In general, individuals in long-term care (LTC) settings are considered to be at increased risk, with one third of residents experiencing a dehydration episode in a 6-month period (Mentes, 2006). However, many of the factors are also characteristic of older adult hospitalized patients as well. See Protocol 9.1 for patient, staff, and family issues that serve as risk factors for dehydration. An example of a tool to determine risk is the Dehydration Risk Appraisal Checklist (Mentes & Wang, 2010) developed to be used by nursing home staff members and based on information that could be retrieved from the Minimum Data Set (MDS; Table 9.2).

TABLE 9.2

Dehydration Risk-Appraisal Checklist

ADL, activities of daily living; BMI, body mass index; GDS, Geriatric Depression Scale; MMSE, Mini-Mental State Examination.

From Mentes and Wang (2010). Reprinted with permission from Mentes and Kang (2011).

At-Risk Populations

Several groups of patients, based on medical diagnosis, are at increased risk of dehydration. These groups include the chronic mentally ill, surgical, stroke, and end-of-life patients.

Chronic Mentally Ill Patients

Special consideration should be given to chronic mentally ill older adults (e.g., individuals with schizophrenia, bipolar disorder, obsessive–compulsive disorder) because they may be at risk of hydration problems. Their antipsychotic medications may blunt their thirst response and put them at increased risk in hot weather for dehydration and heat stroke (Batscha, 1997). In addition, even small increases in their antipsychotic medications may predispose them to neuroleptic malignant syndrome (NMS), of which hyperthermia and dehydration are prominent features (Bristow & Kohen, 1996; Jacobs, 1996; Sachdev, Mason, & Hadzi-Pavlovic, 1997). In these individuals, risks for overhydration stem from a combination of the drying side effects of prescribed psychotropic medications and the individual’s compulsive behaviors that result in excessive fluid intake (Cosgray, Davidhizar, Giger, & Kreisl, 1993).

Patients With Stroke

There is increasing evidence that dehydration may play an important part in contributing to early cerebral ischemia (Rodriguez et al., 2009), and in the early recovery from stroke (Kelly et al., 2004; Lin et al., 2014). In fact, Kelly et al. (2004) found that dehydration in patients with stroke was hospital acquired and led to poorer outcomes for recovering patients with stroke. Dehydration, signified by increased serum osmolality, led to a 2.8- to 4.7-fold increase in the risk of hospitalized patients with stroke acquiring a venous thromboembolism (VTE). Lin et al. (2014) found that by managing stroke patients’ fluid intake based on their admission BUN/creatinine ratio significantly decreased neurological deficits called “stroke in evolution” in older adults with ischemic stroke (2014). Hospitalized patients recovering from stroke should be carefully and continuously monitored for dehydration. Another sequela of stroke is dysphagia, which can cause dehydration (Whelan, 2001). This appears to be related not only to the dysphagia resulting from the stroke but also the poor palatability of the thickened fluids offered to patients to prevent aspiration.

Surgical Patients

Prolonged nothing by mouth (NPO) status before elective surgery has been linked to increased risk of dehydration and adverse effects, such as thirst, hunger, irritability, headache, hypovolemia, and hypoglycemia, in surgical patients (Smith, Vallance, & Slater,1997; Yogendran, Asokumar, Cheng, & Chung, 1995). Crenshaw and Winslow (2002) have found that despite the formulation of national guidelines developed by the American Society of Anesthesiologist Task Force on Preoperative Fasting, patients were still being instructed to fast too long before surgery (Crenshaw & Winslow, 2002). In fact, patients may safely consume clear liquids up to 2 hours before elective surgery using general anesthesia, regional anesthesia, or sedation anesthesia (American Society of Anesthesiologists, 2011).

End-of-Life Patients

Maintaining or withholding fluids at the end of life remains a controversial issue. Proponents suggest that dehydration in the terminally ill patient is not painful and lessens other noxious symptoms of terminal illness, such as excessive pulmonary secretions, nausea, edema, and pain (dehydration acts as a natural anesthetic; Fainsinger & Bruera, 1997). Some suggest additional benefit from the decreased need to stand up to use the restroom and receive bedpans or diaper changes, which could be difficult or painful for someone at the end of life.

Opponents to this position suggest that associated symptoms of dehydration, such as acute confusion and delirium, are stressful and reduce the quality of life for the terminally ill older adult (Bruera, Belzile, Watanabe, & Fainsinger, 1996). Most research that has been done with terminally ill patients with cancer has examined discomforts of dehydration, including thirst, dry mouth, and agitated delirium. However, research has not demonstrated a link between biochemical markers of dehydration and these various symptoms in terminally ill patients (Burge, 1993; Ellershaw, Sutcliffe, & Saunders, 1995; Morita, Tei, Tsunoda, Inoue, & Chihara, 2001). It is suggested that several confounding factors influence the uncomfortable dehydration-like symptoms that accompany the end of life. These include use and dosage of opiates, type and location of cancer, hyperosmolality, stomatitis, and oral breathing (Morita et al., 2001). On the other hand, Bruera et al. (1996) have determined that small amounts of fluids delivered subcutaneously via hypodermoclysis plus opioid rotation was effective in decreasing delirium and antipsychotic use and did not cause edema in terminally ill patients. A 2-day pilot study of parenteral hydration in terminally ill patients with cancer led to statistically significant decreases in hallucination, myoclonus, fatigue, and sedation (Bruera et al., 2005). However, research suggests that artificial hydration does not prolong life (Bruera et al., 2005, 2012; Meier, Ahronheim, Morris, Baskin-Lyons, & Morrison, 2001; Mitchell, Kiely, & Lipsitz, 1997).

Therefore, it is recommended that maintaining or withholding fluids at the end of life be an individual decision that should be based on the etiology of illness, use of medications, presence of delirium, and family and patient preferences (Fainsinger & Bruera, 1997; Morita et al., 2001; Schmidlin, 2008). Schmidlin (2008) recommended early discussions with patients and family on their wishes as well as educating patients on the current knowledge about artificial hydration so that proper patient-centered care will be provided.

Hydration Habits

Hydration habits may indicate the level of risk for dehydration in older adults. Some hydration habits may have developed over a lifetime, and others are adaptations to current health status. Four major categories of hydration habits have been identified (Mentes, 2006). The categories include those older adults who “can drink,” “cannot drink,” “will not drink,” and older adults who are at the “end of life.” For example, older adults who can drink are those who are functionally capable of accessing and consuming fluids but who may not know what is an adequate intake or may forget to drink secondary to cognitive impairment; older adults who cannot drink are those who are physically incapable of accessing or safely consuming fluids related to physical frailty or difficulty in swallowing; older adults who will not drink are those who are capable of consuming fluids safely but who do not because of concerns about being able to reach the toilet with or without assistance or who relate that they have never consumed many fluids; and older adults who are terminally ill comprise the end-of-life category. Understanding hydration habits of older adults can help nurses to plan appropriate interventions to improve or ensure adequate intake (Mentes, 2006).

Indicators of Hydration Status

A priority for nursing, regardless of clinical setting, is the prevention of dehydration. Unfortunately, many of the standard tests for detection of dehydration only confirm a diagnosis of dehydration after it is too late to prevent the episode. In our fast-paced nursing environments, it is difficult to monitor the fluid intake of all our older patients. In using any measure for detection of impending or current dehydration, serial measures offer the greatest likelihood of accuracy (Mentes, 2006). Many studies have used a single test—either biochemical or clinical signs/symptoms—which have insufficient evidence to support diagnostic accuracy (Hooper et al., 2015). Although controversial, urine color and specific gravity have been shown to be reliable indicators of hydration status (not dehydration) in older individuals with adequate renal function in nursing homes and a Veterans Administration Medical Center (Culp, Mentes, & Wakefield, 2003; Mentes, Wakefield, & Culp, 2006). Specifically, the use of urine color, as measured by a urine color chart, can be helpful in monitoring hydration status (Armstrong et al., 1994; Mentes & IVANRC, 2000). The urine color chart has eight standardized colors ranging from pale straw (number 1) to greenish brown (number 8), approximating urine-specific gravities of 1.003 to 1.029 (Armstrong et al., 1994). The urine color chart is most effective when an individual’s average urine color is calculated over several days for an individual referent value. If the older person’s urine becomes darker from his or her average color, further assessment into recent intake and health status can be conducted and fluids can be adjusted to improve hydration status before dehydration occurs. Limitations in using urine indices to estimate specific gravity include (a) certain medications and foods can discolor the urine (Mentes, Wakefield, & Culp, 2006; Wakefield, Mentes, Diggelmann, & Culp, 2002), (b) persons must be able to give a urine specimen for color evaluation, and (c) best results in the use of urine color as an indicator have been documented in older adults with adequate renal function (Mentes et al., 2006). In addition, the timing of collection of urine is also important. In a recent study of younger adults, Perrier et al. (2013) found that a late afternoon (between 4:00 and 8:00 p.m.) specimen best reflected overall hydration status as measured by urine osmolality when compared to a 24-hour urine collection. This would need to be tested with a sample of older adults.

Bioelectrical impedance analysis (BIA) is a measurement that has been used mostly in the fitness industry to estimate body composition, including body mass index (BMI), TBW, and intracellular and extracellular water. Several nursing studies have used impedance measurements to estimate TBW and intracellular and extracellular water (Culp et al., 2003, 2004). Although mostly used in research, BIA is a noninvasive, reliable method used to estimate body water (Ritz & Source Study, 2001). Because TBW is dependent on weight and body composition, this measure is best used after a baseline value of TBW, intracellular, and extracellular fluid in liters has been documented. Then, deviations from the individual baseline can be noted. In a recent Cochrane Review for diagnostic accuracy, a single measure of bioelectrical impedance with resistance at 50 Hz was found to be diagnostic of impending dehydration in two studies and equivocal in two studies (Hooper et al., 2015).

Salivary osmolality is an emerging clinical indicator of hydration status that is sensitive in younger healthy adults (Oliver, Laing, Wilson, Bilzon, & Walsh, 2008) and has been tested in a small sample of nursing home residents (Woods & Mentes, 2011) and older hospitalized adults with a mean age of 78 years (Fortes et al., 2015). Salivary osmolality demonstrated 70% sensitivity and 68% specificity for water-loss dehydration as well as 78% sensitivity and 72% specificity for water and solute dehydration in this study (Fortes et al., 2015).

Indicators of Dehydration

Dehydration is the loss of body water from intracellular and interstitial fluid compartments that is associated with hypertonicity (Mange et al., 1997). Therefore, the most reliable indicators of dehydration are elevated serum sodium, serum osmolality, and BUN/creatinine ratio (Table 9.3). The most common clinical assessments of dehydration include the presence of dry oral mucous membranes, tongue furrows, decreased saliva, sunken eyes, decreased urine output, upper body weakness, a rapid pulse (Gross et al., 1992), and tongue dryness (Vivanti, Harvey, & Ash, 2010; Vivanti, Harvey, Ash, & Battistutta, 2008). Decreased axillary sweat production as a clinical sign of dehydration has produced contradictory results, making it an unreliable indicator of dehydration (Eaton, Bannister, Mulley, & Connolly, 1994; Gross et al., 1992). Assessment of sternal skin turgor as a sign of dehydration has been a mainstay in nursing practice; however, it is also an ambiguous indicator for dehydration in older individuals, with some researchers finding it unreliable because of age-related changes in skin elasticity (Gross et al., 1992) and others finding it reliable (Chassagne, Druesne, Capet, Ménard, & Bercoff, 2006; Vivanti et al., 2008). From a systematic review, Hooper et al. (2015) found that the clinical symptoms/signs of “expressing fatigue” and “missing drinks between meals” were the only measures with the ability to diagnose impending and current dehydration.

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