Hyperosmolar therapy quiz

Here’s a short quiz you can use to test your knowledge. Just 13 True/False questions. I bet you learn something (I did!):

As brain volume increases, volume of CSF and/or blood within the skull must decrease in accordance with the Ned-Kelly Hypothesis

As intracranial pressure reaches 50 to 60 mm Hg, it approaches arterial pressure in the vessels of the circle of Willis and brings about global brain ischemia, the end result of which is brain death.

The pressure–volume relationship within the cranium approximates a linear curve

The brain parenchyma is 80% water, higher than in other organs

The beneficial effect of hyperosmolar therapy requires that the blood–brain barrier be intact

A side effect of mannitol during its first pass through the brain is to increase blood viscosity and causing a reactive dilation of cerebral conductance vessels, which can increase intracerebral blood volume and intracranial pressure.  

Following hyperosmolar therapy, a rebound increase in intracranial volume and pressure can occur after either hypertonic saline or mannitol due to idiogenic osmole formation by astrocytes and neurons

Hartmann’s (Ringer's Lactate) is preferable to normal saline for resuscitation boluses in isolated traumatic brain injury

Factors that may determine whether hypertonic saline or mannitol should be used include all of the following:
  • blood pressure
  • renal function
  • lung water

When using intracranial pressure-guided management, The target intracranial pressure is typically less than 10 mm Hg, with maintenance of cerebral perfusion pressure at 105 to 120 mmHg.

ICP monitoring-based prescription of hyperosmolar solutions results in improved outcome compared with clinical indications or fixed-dose regimens

The following are all features of mannitol therapy:
  • Causes sustained hyperosmolarity by dehydration from osmotic diuresis
  • Typically induces a hypokalemic, hypochloremic alkalosis associated with volume contraction and diuresis
  • Can increase the osmolar gap
  • Can cause acute renal failure in high doses.
  • Can cause considerable skin sloughing if infiltrates the subcutaneous tissues

The following are all features of hypertonic saline therapy:
  • Increases serum osmolarity directly rather than by inducing osmotic diuresis
  • Causes intravascular volume expansion, which may lead to congestive heart failure
  • Can induce mild acidosis, hyperchloremia, and hypokalemia
  • Can cause considerable skin sloughing if infiltrates the subcutaneous tissues

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