How can cerebral edema be prevented in neurosurgery patients with hypernatremia being treated with hypotonic fluids and free water?

From the Guidelines

To prevent cerebral edema in neurosurgery patients with hypernatremia being treated with hypotonic fluids and free water, it is crucial to avoid the use of hypotonic solutions such as Hartmann’s or Ringer’s lactate, and instead, use 0.9% saline or buffered isotonic solutions like Plasmalyte, as these solutions can help maintain normal blood volume, optimize cerebral blood flow, and avoid reduction in plasma osmolarity 1.

Key Considerations

• The primary goal for fluid therapy during neurosurgery is to maintain normal blood volume, optimize cerebral blood flow, and avoid reduction in plasma osmolarity.
• Hypovolaemia and use of hyperosmolar fluids can be detrimental in relation to inadequate cerebral perfusion due to the former or end-organ function due to the latter.
• The potential beneficial effects of HES on the blood-brain barrier in cerebral ischaemia have not been substantiated beyond in vitro modelling; thus, concerns in relation to adverse effects on renal function remain.

Recommendations

• Avoid the use of albumin in patients with traumatic brain injury, as it has been shown to increase mortality in this patient population 1.
• Use isotonic fluids such as 0.9% saline or buffered isotonic solutions like Plasmalyte to maintain normal blood volume and optimize cerebral blood flow.
• Monitor volume status and avoid hypovolaemia, as it can lead to inadequate cerebral perfusion.
• Avoid the use of large volumes of hypotonic fluids, as they can exacerbate cerebral edema 2.

Treatment Approach

• Start with a clear treatment plan that includes frequent monitoring of serum sodium levels, careful calculation of the sodium deficit, and precise administration of isotonic fluids.
• Consider adding desmopressin (DDAVP) if correction is occurring too rapidly.
• Loop diuretics like furosemide may be needed to enhance free water clearance while maintaining sodium levels.
• Continuous infusion of 3% hypertonic saline can be used to temporarily halt a too-rapid decline in sodium.

Osmotic Therapy

• The use of hypertonic saline solutions has been shown to reduce ICP in a variety of conditions, even in cases refractory to treatment with hyperventilation and mannitol 3.
• Mannitol can also be used to decrease ICP, but its use is associated with hypovolemia and the induction of a hyperosmotic state.

From the FDA Drug Label

Use in cerebral edema is not a substitute for careful neurosurgical evaluation and definitive management such as neurosurgery or other specific therapy.

The FDA drug label does not answer the question.

From the Research

Prevention of Cerebral Edema in Neurosurgery Patients

To prevent cerebral edema in neurosurgery patients with hypernatremia being treated with hypotonic fluids and free water, the following strategies can be employed:

• Avoid the use of hypotonic fluids, as they can exacerbate cerebral edema 4, 5
• Use isotonic or hypertonic fluids to maintain normovolemia and prevent a decrease in serum osmolarity 4, 5
• Monitor serum sodium levels and osmolality closely to avoid overcorrection of hyponatremia, which can lead to osmotic demyelination 6
• Use free-water restriction and correction of any reversible causes as the mainstay of treatment for hyponatraemia, unless the patient is symptomatic or has an intracranial catastrophe 6
• Consider the use of hypertonic saline to induce hypernatremia, although the evidence for this approach is limited 7

Key Considerations

When managing fluid therapy in neurosurgery patients, it is essential to consider the following:

• The choice of fluid is crucial to prevent a decrease in serum osmolarity 5
• The primary goal of fluid management is to maintain normovolemia and prevent serum osmolarity reduction 5
• Monitoring of serum sodium levels and osmolality is critical to avoid complications such as osmotic demyelination 6
• The use of hypotonic fluids can exacerbate cerebral edema, and therefore should be avoided 4, 5

Treatment Approaches

Different treatment approaches can be employed to manage cerebral edema in neurosurgery patients, including:

• The use of hypertonic saline to reduce intracranial pressure and cerebral edema 8, 7
• The use of mannitol to reduce intracranial pressure and cerebral edema 4
• The use of free-water restriction and correction of any reversible causes to manage hyponatraemia 6
• The use of vasopressin receptor 2 antagonists to manage hyponatraemia, although more evidence is needed to support this approach 8