Equiosmolar doses of hypertonic saline versus mannitol for brain relaxation in patients undergoing elective craniotomies: an updated systematic review and meta-analysis

Background: Hypertonic saline and mannitol are hyperosmolar agents frequently used to lower ICP and relax the brain during surgeries. Several methods have been used to achieve a good and relaxed brain, such as hyperventilation, cerebrospinal fluid drainage, head position correction, and administration of hyperosmolar agents. Comparing equiosmolar doses between hypertonic saline and mannitol in patients undergoing elective craniotomies is important to further notice the differences in several outcomes. This study aims to compare the outcome of hypertonic saline versus mannitol on brain relaxation in patients undergoing elective craniotomy.Results: 10 articles from 2007 to 2021 were included. Hypertonic saline is associated with better brain relaxation (OR = 1.84, 95% CI 1.31-2.59; P = 0.001) but significantly increase blood natrium level, both serum and arterial (MD = 3.03, 95% CI 1.70-4.36; P = < 0.001 and MD = 7.14, 95% CI 0.04-14.24; P = < 0.001, respectively). Mannitol was associated with increased fluid input and urine output (SMD = - 0.56, 95% CI - 0.98 to - 0.15; P = < 0.001 and SMD = - 0.96, 95% CI - 1.42 to - 0.50; P = < 0.001, respectively). Serum osmolality and hemodynamic parameters difference was insignificant.Conclusions: ypertonic saline is associated with significantly better brain relaxation score and increased blood sodium level without increase in urine. This may prove to be clinically significant in patients with electrolyte imbalance.

Automated summary

Hypertonic saline is associated with better brain relaxation and increased blood sodium level compared to mannitol in patients undergoing elective craniotomy. Mannitol, on the other hand, is associated with increased fluid input and urine output. There was no significant difference in serum osmolality and hemodynamic parameters between the two agents.