Chapter 8 Implications of Abnormal Hydration Status

TABLE 8.2 Hypotonic Dehydration Lab Test

Osmolality, serum Sodium, serum Albumin BUN

BUN:creatinine ratio Urine-specific gravity

Abbreviation: BUN, blood urea nitrogen.

needs must also be monitored, with supplements pro- vided as needed (42). Table 8.2 summarizes what happens in hypotonic

dehydration. Hypertonic Dehydration

“In hypertonic dehydration, water loss exceeds salt loss—that is, when more water than sodium is lost” (43). Hypertonic dehydration is more common in people not getting enough nutrients, including fluids, through their diets due to excessive sweating, infection or fever, watery diarrhea, and excessive vomiting and is often seen in those with diabetes. It may also be caused by elevated environmental temperature, thera- pies such as air-fluidized beds and dry oxygen, and medications such as diuretics, laxatives, and cardiac glycosides.

Inadequate staffing (16), infirmity, functional dependence, dementia, and reduced consciousness can also contribute to hypertonic dehydration because these conditions can inhibit the older adult’s water intake. Hypertonic dehydration is characterized by an osmotic shift of water from the intracellular fluid to the extracellular fluid. Water intake for whatever reason decreases. This may occur in, for example, an older adult with throat or esophageal cancer resulting in dysphasia. Other causes may include staff not pro- viding adequate fluids and the older adult being unable to obtain them independently or infusing solu- tions without proper hydration, especially in those receiving saline solutions or enteral/parenteral feed- ings. Lastly, it may be because of high fever, perspira- tion, burns, or uncontrolled diabetes. In mild hypertonic deficit, older adults may experi- ence a water deficit of 2% to 4% of body weight. Thirst

is associated with this type of dehydration but unfortu- nately may not be identified by the older adult. Those with moderate hypertonic deficit often have fatigue, lower urine output, dry tongue, decreased elas- ticity of the skin, sunken eyes, and restlessness. In these cases, water deficit is around 4% to 6% of body weight.

Finally, in severe hypertonic water deficit, all the symptoms identified for those with mild and moderate hypertonic water deficit are usually identified along with changes in cognitive function, such as mania, hallucina- tions, delirium, and, in worst-case scenarios, coma. Water loss is now more than 6% of body weight. Those with hypertonic dehydration are diagnosed using the resident’s history, clinical manifestations that are identified by the health care professional, critical thinking, and laboratory values such as increases in urine-specific gravity, increased levels of red blood cells, hemoglobin, and hematocrit, and a serum sodium level that is more than 150 mEq/L.

Hypertonic dehydration is treated by determining and then removing the causes. Often it is a matter of using an intravenous infusion of glucose or sodium chloride, replenishing fluid volume based on the sodium concentration and fluid needs. Fluid is replen- ished by providing the daily requirement plus half of the calculated volume. Potassium supplementation should be provided when urine output is more than 40 mL/h and sodium bicarbonate should be provided in acidosis (19). Table 8.3 summarizes what happens in hypertonic

dehydration.

129

Normal Values

285–295 mOsm/kg water 136–145 mEq/L 3.5–5 g/dL

10–20 mg/dL 10:1

1.005–1.030

Hypotonic Dehydration < 295 mOsm/kg water < 136 mEq/L Above normal Above normal > 25:1

< 1.005