Page 337 - Critical Care Nursing Demystified

322 CRITICAL CARE NURSING DeMYSTIFIED

Hallmark Signs and Symptoms
The patient may experience generalized weakness, dehydration, increased thirst
(polydipsia), a very low specific gravity of less than 1.005, increased sodium levels
of greater than 145 mEq/mL and polyuria of greater than 300 mL/hr of very dilute
(tasteless or insipid) urine. A huge cycle of polyuria and polydipsia continues, which
creates significant disruptions in a person’s schedules and quality of life. Hypoten-
sion, tachycardia, and shock can reveal signs of cardiovascular impairment. Also
observe for signs of CNS involvement such as mental dullness, irritability, and
coma. Additional problems that can occur include constipation from fluid loss or
diarrhea from intestinal hyperactivity associated with vasopressin drug therapy.

3 Patient Assessment
Obtain a medication history that could help to identify ADH imbalances. Drugs
that increase ADH release are barbiturates, anesthetics, vincristine, and gluco-
corticoids. Those that decrease ADH are Dilantin, reserpine, and chlorpromaz-
ine. A social history is also necessary to identify the patient’s compulsive or
unsatisfied water drinking and unexplained weight loss. Continuously assess the
patient’s hydration status through accurate measurement of intake and output,
daily weights, and determination of skin turgor and buccal membranes, as severe Downloaded by [ Faculty of Nursing, Chiangmai University 5.62.158.117] at [07/18/16]. Copyright © McGraw-Hill Global Education Holdings, LLC. Not to be redistributed or modified in any way without permission.
dehydration and hypovolemia can result from polyuria and polydipsia.
Fluid and electrolytes are routinely drawn and evaluated. ADH levels, serum
osmolality, urine osmolality, and serum sodium levels are obtained and compared.

Interpreting Test Results
Laboratory value changes associated with DI are shown in Table 7–4.
Also of diagnostic value is the Water Deprivation or Dehydration Test.
The patient is deprived of fluids for 24 hours. Urine and serum osmolality is
measured during this time. In patients with DI, their urine will be minimally
concentrated after forced dehydration and their serum osmolality will rise
above 300 mOsm. Sodium levels will increase above 145 mEq/mL. Individuals
with DI show no decrease in urine volume in response to strict water restric-
tion, whereas healthy people respond with a rapid decline in urine volume
when water intake is withheld.
The priority of care is to restore and maintain circulating fluid volume and
osmolality and prevent circulatory collapse through ADH replacement. For those
patients who can drink, they are given fluids orally and hourly in amounts to
match their fluid loss and output. Intravenous hypotonic solutions of 0.45% NSS
can be given to correct hypernatremia. A low sodium diet might be beneficial to
the patient with DI, along with fluid restriction of 500 to 1,000 mL per day.