All Sample Questions

Treatment for Elevated Intracranial Pressure 1

Question

Vignette: A 24-year-old male is brought to the hospital after being involved in a motorcycle accident. He is unconscious and CT scan reveals a severe traumatic brain injury. The physician notes that the patient's intracranial pressure is significantly elevated. The patient is immediately intubated and placed on mechanical ventilation to protect his airway. The physician orders administration of a hyperosmotic solution to decrease the intracranial pressure. Which of the following is the most likely mechanism of action of the hyperosmotic solution?

Choices

A) Osmotic diuresis

B) Increased brain oxygenation

C) Decreased cerebrospinal fluid production

D) Vasoconstriction of cerebral blood vessels

E) Decreased metabolic rate of brain tissue

Answer

A) Osmotic diuresis

Explanation

Hyperosmotic solutions like mannitol are used to reduce elevated intracranial pressure (ICP) in conditions like traumatic brain injury. They work primarily by creating an osmotic gradient between the brain and the blood. This draws water out of the brain tissue and into the bloodstream, thereby reducing cerebral edema and ICP. This process is termed osmotic diuresis. Mannitol is filtered but not reabsorbed in the renal tubule, so it also increases urine output, which further helps to decrease ICP by reducing total body water. The other choices, while physiologically relevant, are not the primary mechanisms by which hyperosmotic solutions decrease ICP.