Chapter 8 Implications of Abnormal Hydration Status

BOX 8.3 Indicators of Risk or Presence of Dehydration

● Has one or more of the following: change in mental status cracked lips diarrhea

➤ ➤ ➤ ➤ ➤ ➤ ➤

dry mouth fever

postural hypotension

pulse over 100 beats per minute and/or systolic blood pressure under 100 mm Hg

➤ ➤ ➤ ➤ ➤

recent, rapid weight loss small amounts of dark urine sunken eyes

urinary tract infection vomiting

● Needs help drinking from a cup or glass ● Drinks less than 6 c of liquids daily ● Trouble swallowing liquids ● Easily confused/tired ● Lethargic/weak ● Falls frequently

● ● Increased combativeness/confusion

Change in abilities to perform activities of daily living

are less able to concentrate urine (30). Also, ill older adults are less able to respond to vasopressin (31,32). Total body water also declines with aging due to a decline in lean body mass, which increases risk of cel- lular dehydration (33).

Medical Factors

Several medical conditions and therapies interfere with fluid homeostasis. One study (34) identified the follow- ing factors associated with volume depletion:

● ● ● ● ● ● ●

febrile illness infirmity surgery

high-protein diets

high-solute intravenous fluids diabetes diarrhea

● GI bleeding diuretics

● ● renal dialysis

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Older adults are especially prone to infections (19), which account for up to 25% of acute hospitalizations or emergency room visits for this group (35). Fevers associated with infections increase insensible losses through perspiration, respiration, and increased metab- olism. As stated previously, water losses increase by 100 to 150 mL/d for each degree of temperature above 37°C (98.6°F) (23).

Polypharmacy has been associated with dehydra- tion in older people. Some medications, such as diuret- ics and cardiovascular agents, contribute directly to the risk of dehydration. The antiseizure medication phe- nytoin interferes with the action of vasopressin (36). Other classes of medications indirectly contribute to dehydration risk. Sedative and ethanol use in older adults, as well as conditions that depress the level of consciousness, can interfere with adequate intake of fluids.

Gastrointestinal (GI) fluid losses due to vomiting, bleeding, nasogastric and fistula draining, laxative abuse, and diarrhea increase risk of dehydration. High-solute IVs and high-protein intakes can also cause dehydration if additional fluid is not given, because they increase renal solute load, which increases fluid needed for urinary excretion of solute. Urine volume must parallel renal solute load. In adults, each gram of protein theoretically contributes 5.7 mOsm to renal solute load (37).

ASSESSING HYDRATION STATUS Because dehydration is associated with significant morbidity and mortality in older adults, the Centers for Medicare & Medicaid Services (CMS) launched a Nutrition/Hydration Awareness Campaign to call atten- tion to early warning signs of unintended weight loss and dehydration among residents of LTC facilities (38).

In 2009, the American Medical Directors Association (AMDA) published their revised dehydra- tion and fluid maintenance clinical practice guidelines. These guidelines state that for a clinical diagnosis of dehydration to be made, the following minimal criteria must be present (2):

●

suspicion of increased output and/or decreased intake;

●

at least two physiological or functional signs or symptoms suggesting dehydration (eg, dizziness, dry mucous membranes, functional decline); and

●

a blood urea nitrogen (BUN):creatinine ratio above 25:1 or orthostasis (defined as a drop in systolic blood pressure that is at least 20 mm Hg or higher with a change in position) or a pulse of greater than 100 beats/min or a pulse change of