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Part II Nutrition Assessment, Consequences, and Implications

TABLE 8.1 Isotonic Dehydration Lab Test

Osmolality, serum Sodium, serum Albumin BUN

BUN:creatinine ratio Urine-specific gravity

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 Abbreviations: WNL, within normal limits; BUN, blood urea nitrogen.

characterized by an osmotic shift of fluid from the extracellular to the intracellular areas (40). This com- plication can be life-threatening if swelling causes pressure on the brain, known as cerebral edema. Repeated vomiting and GI suction over a long period causes continual loss of GI juice and possible hypotonic dehydration. This type of dehydration can also be caused when there is a large wound area such as in burns or multiple pressure areas with exudates. In older adults, hypotonic dehydration can occur when diuretics are used, especially if used in conjunction with low-sodium diets and/or in those with kidney disease. Although rare, it can also occur due to exces- sive intakes of plain water or other liquids with little or no sodium content. This excessively dilutes the level of sodium in the body and may cause the body’s cells to swell; this is known as dilutional hyponatremia (21). Hypotonic dehydration manifests in numerous clinical ideologies just as isotonic dehydration. Health care professionals need to monitor individuals who have any of these symptoms, including diminished thirst, GI disturbances, diminished vision, weakness, rapid pulse, and orthostatic hypotension. In hypotonic dehydration, the blood volume falls and there is subse- quent decreased renal filtration. Because of this, meta- bolic product retention increases, causing muscle spasms and changes in overall reflexes. In severe hypo- tonic dehydration, coma may occur (40). Because of this, sodium deficit levels are classified as mild, mod- erate, and severe, each with its own signs and symptoms.

In mild sodium deficit, the older adult has an increase in fatigue and may complain of numbness in the extremities. Sodium in the urine falls, and sodium

blood levels are less than 135 mEq/L. Sodium loss is about 0.5 g/kg. With moderate sodium deficits, more clinical man- ifestations may occur. Nausea and vomiting are more prominently seen, and pulse and blood pressures often are abnormal. The older adult may also complain of vision problems and may have fainting episodes related to orthostatic hypotension. There is a decrease in urine output with no sodium or chloride in the urine, and serum blood levels of sodium are decreased even more to 130 mEq/L with sodium losses of 0.5 to 0.75 g/kg.

Severe sodium deficit in hypotonic dehydration produces symptoms ranging from mild nonspecific complaints, such as malaise and apathy, to marked central nervous system impairment. In these cases, serum sodium is less than 120 mEq/L, with sodium losses estimated at 0.75 to 1.25 g/kg (42). Residents with hypotonic dehydration are diag- nosed using their history, evidence of clinical manifes- tations that are identified by the health care professional, and laboratory values such as increases in red blood cells, hemoglobin, and hematocrit; low serum sodium; and increases in both nonprotein nitro- gen and BUN.

Hypotonic dehydration is treated by determining and then removing the causes. Providing a hypertonic saline infusion is the treatment of choice, providing both sodium chloride and protein solution (42). The goal of using hypertonic saline infusions is to treat the sodium deficit and acidosis. If the acidosis continues after the infusion is completed, then sodium bicarbon- ate or a balanced salt solution may be tried. Potassium

Isotonic Dehydration WNL WNL

Above normal Above normal > 25:1

> 1.031