86. A nurse knows that the serum sodium level of a client with a head trauma should be above 140 to:
86. A nurse knows that the serum sodium level of a client with a head trauma should be above 140 to:
. Keep cerebral perfusion pressure up.
. Prevent cerebral vasodilation.
. Lower the seizure threshold.
. Prevent cerebral edema.
Test-Taking Tip
Remember: H2O follows sodium. The desired clinical outcome is to reduce or prevent cerebral edema.
Content Area: Adult Health, Fluid and Electrolyte Imbalances; Integrated Process: Nursing Process, Analysis; Cognitive Level: Application; Client Need/Subneed: Physiological Integrity/Reduction of Risk Potential/Laboratory Values
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Answer 1 is incorrect because cerebral perfusion is determined by the pressure of the blood flowing into the brain and the resistance to inflow created by intracerebral pressure. Answer 2 is incorrect because cerebral vasodilation is largely determined by PaCO2. It is important to ensure good ventilation in clients who have had trauma, but this is unrelated to serum sodium. Answer 3 is incorrect because lowering the seizure threshold would make the client more at risk for seizures, which is never desirable. Low serum sodium levels can increase seizure risk. Answer 4 is correct because osmolarity is largely determined by serum sodium. If the sodium level is low, water will move from the bloodstream into the cells. The client is already at risk for cerebral edema because of the injury. The swelling could result in a dangerous increase in intracerebral pressure.