Page 335 - Critical Care Nursing Demystified

320 CRITICAL CARE NURSING DeMYSTIFIED

sodium loss and fluid retention at the site of the kidney tubules, sodium can be
replaced via 3% intravenous hypertonic saline solution infused at a slow rate of
0.1 mg/kg per minute on an infusion pump to prevent rapid volume overload
and pulmonary edema.

Interpreting Test Results
Laboratory tests combined with the patient’s clinical profile are the best indica-
tors of the amount of ADH released into the bloodstream. The serum ADH test
measures the amount of ADH present in a frozen sample of blood.
The normal result is 1 to 5 pg/mL. A more accurate direct measurement of
ADH is possible through a sensitive radioimmunoassay serum ADH test. BUN,
albumin, creatinine, hemoglobin, hematocrit, and electrolyte values may also
be affected and should be evaluated.
Laboratory value changes associated with SIADH are shown in Table 7–3.
A water load test might be done to confirm a diagnosis of SIADH by creating
a quasi-state of water intoxication. The patient is overhydrated with water after
a period of fasting. Urine output and serum osmolality are monitored. Serum
osmolality levels will decrease, and despite the excessive water load, an inability
to excrete dilute urine will be evident. Overhydration is difficult for the patient
and is generally never performed if the patient’s condition is critical. 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.

Prognosis
Individuals at risk for SIADH who are identified and cared for early in their
illness can expect a full recovery.

3 and 5 Nursing Diagnosis
for SIADH Expected Outcomes
Fluid volume deficit related to Sodium levels will return to normal status
dilutional hyponatremia and Status of dehydration will improve
dehydration

TABLE 7–3 Laboratory Value Changes Associated With SIADH
Test Normal Values Change
Serum ADH 1–5 pg/mL Elevated
Serum osmolality 285–300 mOsm/kg <250 mOsm/kg
Serum sodium 135–145 mEq/mL <120 mEq/L
Urine osmolality 300–1400 mOsm/kg Increased
Urine specific gravity 1.005–1.030 >1.030
Intake and output Fluid intake will remain Urine output will be below
unchanged. normal.