Hyperosmolar Therapy for the Brain Injured Patient

  • When treating patients with severe brain injury, a major goal is to prevent secondary brain injury. This entails increasing oxygen delivery to the brain by preventing hypoxia and increasing cerebral perfusion.
  • Cerebral Perfusion Pressure (CPP) = Mean Arterial Pressure (MAP) - Intracranial Pressure (ICP). To increase CPP, one must either increase MAP and/or decrease ICP. When ICP is elevated, hyperosmolar therapy (i.e., mannitol and hypertonic saline), is used to decrease ICP by decreasing the brain volume and hence the ICP. 
  • A study conducted by Boone et al. reviewed 7 articles comparing mannitol vs. hypertonic saline in severe TBI. The study concluded that both agents are effective at reducing ICP with mixed results regarding superiority.
  • Another meta analysis conducted by Rickard et al. found similar results with a trend towards favoring hypertonic saline. A limiting factor in both studies is varying methodology between different studies. 
  • While there is no clear winner between mannitol and hypertonic saline it is clear that both decrease ICP, thereby increasing CPP and reducing the risk of secondary brain injury.