Perioperative Intravenous Fluid Therapy
Fluid management is an important component of perioperative care for patients undergoing neurosurgery. The primary goal of fluid management in neurosurgery is the maintenance of normovolemia and prevention of serum osmolarity reduction. To maintain normovolemia, it is important to administer fluids in appropriate amounts following appropriate methods, and to prevent a decrease in serum osmolarity, the choice of fluid is essential. There is considerable debate about the choice and optimal amounts of fluids administered in the perioperative period. However, there is little high-quality clinical research on fluid therapy for patients undergoing neurosurgery. A review of Ryu discussed the choice and optimal amounts of fluids in neurosurgical patients based on the literature, recent issues, and perioperative fluid management practices.
Despite numerous studies on perioperative intravenous fluid therapy, there is insufficient evidence to draw definitive conclusions regarding fluid management in neurosurgical patients. Although evidence is still lacking, isotonic balanced crystalloid solutions should be considered the first-choice fluid, while hypotonic solutions should be avoided. Furthermore, colloid solutions should be used with caution, and their potential risks and benefits should be considered. To achieve an optimal fluid volume status while avoiding overhydration and excessive restriction, the amount and duration of fluid administration should be considered, and an individualized fluid strategy is recommended using Goal-directed fluid therapy based on dynamic fluid parameters 1).
A crystalloid fluid contains small molecular substances without high molecular substances, and it is classified as hypotonic, isotonic, or hypertonic according to its osmolarity. Lactated Ringer's solution (LR), a commonly used crystalloid, is hypotonic at 273 mOsm/L. Low plasma osmolarity can cause cerebral edema. Therefore, hypotonic solutions, such as LR, are avoided, while normal saline (NS) has traditionally been used as the main fluid in patients with neurosurgery 2).
Patients who received balanced crystalloid (BC) during Unruptured Intracranial Aneurysm Clipping had lower incidence of metabolic acidosis, earlier extubation and shorter ICU stay compared to those who received NS. Therefore, using BC as a peri-operative fluid can be recommended for patients who undergo surgery for UIA 3).
In prone elective neurosurgical patients, the baseline values of pulse pressure variation (PPV) and stroke volume variation (SVV) and the end-expiratory occlusion test (EEOT) fail to predict fluid responsiveness, while the tidal volume challenge (VTC) is a very reliable functional hemodynamic test and could be helpful in guiding intraoperative fluid therapy 4).