Nursing Center - Journal Issue

WATER IS ONE of the most important nutrients for maintaining life and ensuring healthy aging. Body fluids move nutrients, gases, and wastes throughout the body; are essential in metabolizing food into energy; and generally assist in the body's functions.1

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Monitoring your patients' fluid status can prevent dehydration-a potentially fatal condition-and its complications.2Dehydration is defined as a rapid loss of more than 3% of body weight that's associated with water and electrolyte disturbance from either water or sodium depletion.3

This article focuses on assessing for and managing dehydration in older adults.

Aging increases risk

Older adults, who are more likely to have serious and chronic conditions than their younger counterparts, are at increased risk for dehydration, one of the most frequent causes of hospitalization in adults ages 65 to 75.4 Age-related changes are another reason for this preventable shift in water balance.5 According to the Agency for Healthcare Research and Quality (AHRQ), the hospitalization rates for dehydration increase substantially with age.6

This problem is likely to grow, too. By the year 2030, the number of Americans age 65 and older is expected to grow from 39 million in 2008 to 72 million.7

According to AHRQ's Guide to Prevention Quality Indicators, hospital admission for dehydration is a Prevention Quality Indicator (PQI). This is a screening tool for potential quality issues that may reflect the quality of care provided in community settings.2

To fully understand the serious implications of dehydration for older adults, refresh your knowledge of the pathophysiology underlying the condition.

A delicate balance

Total body water (TBW), which accounts for about 60% of a healthy younger adult's body weight, is found in the intracellular (ICF) and extracellular fluid (ECF) compartments.8 The fluid in the ICF makes up about 40% of adult body weight, while fluid in the ECF makes up about 20%. However, a particular person's water content depends on the amount of adipose tissue or fat, which is only about 10% water. Compare this to skeletal muscle, which is about 75% water. An adult who's obese may have TBW that's only 30% to 40% of body weight.1 (See Comparing TBW.)

TBW also declines with age, with women having lower TBW than men of the same age. In young men, TBW is about 60% of body weight, but in older men it's about 50%; in young women, it's about 50%, and in older women, about 40%.1

Figure. Comparing TB... - Click to enlarge in new window

Figure. Comparing TBW

Hydration of the ICF and ECF compartments is regulated separately. Intracellular hydration is regulated primarily by changes in osmolality, which responds to osmoreceptors in the thirst center in the hypothalamus. Extracellular hydration is primarily regulated by blood volume, which responds to baroreceptors in the cardiac atria, large pulmonary vessels, aortic arch, and carotid sinus.1,9

Requirements for water intake depend on many factors, including the patient's age and level of physical activity. The main source of water gain is through oral intake and metabolism of nutrients.1 Healthy people of any age need about 100 mL of water per 100 calories metabolized to dissolve and eliminate metabolic wastes. For example, someone who burns 1,800 calories needs about 1,800 mL of water for metabolic purposes.1,8 Miller suggests that consuming 1,500 to 2,000 mL of noncaffeinated fluid in 24 hours will maintain adequate hydration in older adults.8

A healthy adult loses around 2,500 mL of body water daily. Usually most water is lost through the kidneys, with smaller amounts lost through the gastrointestinal tract, skin, and lungs. Because water is lost through the skin and lungs without a person being aware of it, these losses are called insensible water losses.1 (See Sources of body water gains and losses in the adult.)

The body attempts to conserve water by concentrating urine via feedback systems that produce an increase in renal sodium and water retention. Conversely, excess water intake is excreted by the kidneys as dilute urine, via feedback mechanisms that decrease sodium and water retention.1 A decrease in blood volume or an increase in ECF osmolarity stimulates the thirst mechanism, leading the person to increase fluid intake.

Considering the risks

Dehydration is a common cause of morbidity and mortality in older adults. Dehydration can be classified as isotonic, hypertonic, or hypotonic. (See Classifying dehydration.)

Risk factors for dehydration include:

* age greater than 85

* institutionalization

* dependencies in feeding and eating

* dementia

* infections

* history of dehydration.5

Additional risk factors for dehydration include female gender, more than four chronic conditions, more than four medications, immobility, and laxative use.10 Other risk factors include dysphagia secondary to stroke; conditions associated with an increased demand for fluid, such as hyperglycemia, or an increased loss of fluids such as diarrhea or vomiting; medications that increase fluid losses, such as diuretics; sedating medications that decrease the ability to obtain or desire for fluid intake, such as antihistamines or antidepressants; environmental conditions, such as extremes in heat; and cognitive deficits such as dementia or delirium. Delirium can also be a sign of dehydration in older adults.11

Normal age-related physiologic changes that contribute to dehydration, particularly in those age 85 and older, include changes in body composition resulting in decreased TBW, decreased renal function, and decreased thirst.5,11,12 Age-related changes in body composition include decreased lean body mass. Decreased renal function results from decreased renal mass, decreased renal blood flow, decreased glomerular filtration rate (GFR), and diminished creatinine clearance.1 The ability of the kidneys to respond to aldosterone and antidiuretic hormone also decreases with age.13 Older adults frequently experience decreased thirst perception as well.12

Older adults with functional decline and altered mobility are at higher risk for dehydration because they may not be able to independently access fluids. Other causes of dehydration include psychosocial factors, such as inadequate patient education about medications and types and amount of fluids to drink; lack of social support; and fear of falling or of incontinence, which may lead older adults to restrict fluid intake.

Assessing your patient

Use a systematic approach to identify risk factors to prevent dehydration or to identify signs and symptoms consistent with dehydration in your older patients so you can quickly intervene and help prevent complications. (See Look for these signs and symptoms.) Obtain a comprehensive health history for older adults in all healthcare settings and update it regularly.14 The history should include:

* diseases that put a patient at risk, such as dementia, heart failure, chronic kidney disease, malnutrition, and mental health disorders such as depression.

* medications, including prescription and over-the-counter drugs and herbal and nutritional supplements.

* any history of dehydration or repeated infections.

* a review of systems for possible sources of fluid loss.5

When you perform medication reconciliation, identify medications that could alter fluid and electrolyte balance. For example, dehydration risk increases with the use of diuretics, vasodilators, beta-blockers, aldosterone inhibitors, angiotensin-converting enzyme (ACE) inhibitors, angiotensin receptor blockers, and lithium.14 Some medications can cause syndrome of inappropriate secretion of antidiuretic hormone, including tricyclic antidepressants, selective serotonin reuptake inhibitors, phenothiazines, vasopressin, and some antineoplastic drugs.

Table. Sources of bo... - Click to enlarge in new window

Table. Sources of body water gains and losses in the adult

Physical assessment should include vital signs, height and weight, body mass index, and major body systems with special attention to any signs and symptoms suggesting dehydration.

Although tachycardia is a compensatory mechanism to increase cardiac output in younger, healthy adults with dehydration, older adults may not exhibit tachycardia, especially if they're taking medications such as beta-blockers or calcium channel blockers.14 In addition, many signs and symptoms aren't specific to dehydration. For example, dry mucous membranes can also be caused by anticholinergic medications, and postural hypotension may be an adverse reaction to antihypertensive medication.

Besides delirium, other atypical signs and symptoms of dehydration in older adults include falls, muscle weakness, changes in functional status, fatigue, confusion, or changes in level of consciousness.11 Don't assume that confusion is normal in older adults. Instead, promptly assess any change in mental status from baseline.11

Any strategy preventing readmission benefits patients while reducing department workload and length of stay.19 Include medical, nursing, occupational therapy, and dietary staff. Appoint fluid and diet monitors on each shift to assess and document older patients' hydration and eating habits, fluid preference, and preferred beverage temperature.14

Use assessment tools to identify dehydration risk and nutritional imbalance so you can implement preventive and therapeutic interventions.8 One such tool, the Dehydration Risk Appraisal Checklist, can be downloaded from http://rgp.toronto.on.ca/torontobestpractice/Dehydrationriskappraisalchecklist.p.

Focus patient education on the importance of hydration and of drinking even when not thirsty. Aim for early recognition of any decrease in your patient's usual fluid intake patterns. Replenish and refresh fluids regularly. Frequently offer and encourage your patient to drink preferred fluids or eat fluid-rich foods, ensure access to drinks, and position the patient comfortably so drinking straws, feeder cups, or special drinking apparatus can be used. Incorporate swallowing exercises, if needed. Use visual reminders such as posters or notes.14

Besides assessing and monitoring for dehydration in hospitalized patients, emphasize preventive practices at home where recovery and rehab often continue.20 Dehydration may delay rehab or result in hospital admission or readmission.

Patient teaching

As a nurse, you're in an ideal position to identify older adults at risk for dehydration and to educate them and their families. Inform them about the benefits of hydration and raise their awareness of the potential risks associated with increasing age and psychosocial factors.

Interventions to promote hydration include encouraging family and visitors to provide fluids and reminding older adults about drinking fluids.3 You can ease older adults' fears about incontinence and falls by providing education and connection with state and federally funded community resources such as all-inclusive older adult centers. The Program of All-Inclusive Care for the Elderly (PACE) includes comprehensive services with an interdisciplinary team of professional and paraprofessional staff to assess participants' needs and to develop and implement individual care plans.

Improving outcomes

Don't just go with the flow: Take dehydration seriously and implement proper strategies to prevent it or reverse its course. Your astute nursing care can prevent hospital admissions and readmissions-so turn on the taps for best practices.

Classifying dehydration

* Isotonic dehydration: a balanced depletion of water and sodium that causes ECF loss. Causes include vomiting and diarrhea.

* Hypertonic dehydration: depletion in TBW content due to pathologic fluid losses, diminished water intake, or both. Because of the resulting hypernatremia in the ECF compartment, water is drawn from the ICF compartment.

* Hypotonic dehydration: depletion in sodium and water in which sodium loss predominates, resulting in ECF loss. Causes include overuse of diuretics, renal disease, and decreased intake of sodium and water.

Source: Hartford Institute for Geriatric Nursing. Need Help Stat. Consider: Hydration Management. http://consultgerirn.org/topics/hydration_management/need_help_stat/.