Purpose of review
In patients with traumatic brain injury (TBI), dysfunction of the neurovascular unit (‘blood–brain barrier’) is a common finding, resulting in maldistribution of water and osmoles within the brain. The purpose of the present article is to review the underlying physiology of osmolality and fluid therapy in TBI.
The findings of the ‘Saline versus Albumin Fluid Evaluation’ study suggest that infusion of colloidal solutions is associated with adverse outcomes as compared with sole crystalloid infusion in patients suffering from TBI. Comparison of calculated osmolarity and measured in-vitro osmolality suggests that human albumin solutions, Hartmann's solution, and, to a lesser extent, gelatine preparations are hypo-osmolar, and may, therefore, increase brain volume and intracranial pressure.
In the context of the published literature on this topic, it appears that the osmolality of an infusion solution rather than the colloid osmotic pressure per se represents the key determinant in the pathogenesis of cerebral edema formation.