The provider orders mannitol IV for a client admitted to the ICU with a closed head injury. Following the administration of mannitol, the nurse expects which of the following?

Increased urinary output


• Mannitol is an osmotic diuretic. Osmotic diuretics make the blood hypertonic, which creates a concentration gradient to pull fluid away from the intracellular compartment (including the intracranial space, where the brain cells are swelling) into the intravascular compartment. Excess fluid volume in the blood increases pressure of the glomerular filtrate leading to diuresis.

• The therapeutic effect of mannitol is decreased cerebral edema and decreased intracranial pressure (ICP). The nurse can expect to observe diuresis and reduced ICP within 30-60 minutes after IV administration. The nurse evaluates effectiveness by monitoring ICP (which should decrease) and urinary output (which should increase).

• Mannitol is contraindicated in patients with dehydration, anuria, active intracranial bleeding, or severe pulmonary edema or congestion. Adverse effects may include headache, pulmonary edema, tachycardia, thirst, nausea, hyper or hypokalemia, hyper or hyponatremia, and transient volume expansion.

• Clients with closed head injuries are expected to have altered levels of consciousness. When decreased level of consciousness (LOC) is caused by increased ICP, administration of mannitol may lower the ICP and aid in improvement of symptoms, including an increased LOC.

• The actions of mannitol will not have any effect on the client's white blood cell count.

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