High-osmolarity saline in neurocritical care: systematic review and meta-analysis

Intracranial hypertension and cerebral edema are known contributors to secondary brain injury and to poor neurologic outcomes. Small volume solutions of exceedingly high osmolarity, such as 23.4% saline, have been used for the management of intracranial hypertension crises and as a measure to prevent or reverse acute brain tissue shifts. We conducted a systematic literature review on the use of 23.4% saline in neurocritically ill patients and a meta-analysis of the effect of 23.4% saline on intracranial pressure reduction.

We searched computerized databases, reference lists, and personal files to identify all clinical studies in which 23.4% saline has been used for the treatment of neurocritical care patients. Studies that did not directly involve either effects on cerebral hemodynamics or the treatment of patients with clinical or radiographic evidence of intracranial hypertension and/or cerebral swelling were eliminated.

We identified 11 clinical studies meeting eligibility criteria. A meta-analysis was performed to evaluate the percent decrease in intracranial pressure and the 95% confidence intervals, from baseline to 60 minutes or nadir from the six studies from which this information could be extracted. A fixed effects meta-analysis estimated that the percent decrease in intracranial pressure from baseline to either 60 minutes or nadir after administration of 23.4% saline was 55.6% (se 5.90; 95% confidence interval, 43.99-67.12; p < 0.0001).

Highly concentrated hypertonic saline such as 23.4% provides a small volume solution with low cost and an over 50% reduction effect on raised intracranial pressure. Side effects reported are minor overall in view of the potentially catastrophic event that is being treated. High quality data are still needed to define the most appropriate osmotherapeutic agent, the optimal dose, the safest and most effective mode of administration and to further elucidate the mechanism of action of 23.4% saline and of osmotherapy in general.