Fluid of Choice in Traumatic Brain Injury
Normal saline 0.9% is the crystalloid of choice for TBI management, as it is the only commonly available isotonic crystalloid solution that prevents increases in brain water. 1
Why Normal Saline is Preferred
The fundamental principle in TBI fluid management is maintaining isotonicity based on real osmolality (mosmol/kg) rather than theoretical osmolarity (mosmol/L). 1
Normal saline 0.9% is the only commonly available isotonic crystalloid when measured by real osmolality, making it the current standard for brain injury resuscitation. 1
Ringer's lactate (compound sodium lactate) and Ringer's acetate are hypotonic when real osmolality is determined and should be avoided in TBI, as they can increase brain water content. 1
Gelatins and other synthetic colloids are also hypotonic by real osmolality measurements and are not recommended. 1
What to Avoid: Critical Contraindications
Albumin 4% solution is specifically contraindicated in severe TBI patients based on high-quality evidence. 1
The SAFE study demonstrated significantly increased mortality in severe TBI patients receiving 4% albumin (24.5% vs. 15.1%, RR: 1.62, P = 0.009) compared to normal saline. 1
Two-year follow-up data confirmed this harm, with mortality of 41.8% with albumin versus 22.2% with saline (RR: 1.88, P < 0.001). 1
The hypotonic nature of 4% albumin infusion likely contributes to worsened outcomes by increasing brain water. 1
Resuscitation Goals and Fluid Strategy
The primary aims of fluid management in TBI are to reverse hypovolemia, avoid hypotension, and maintain cerebral blood flow to limit cerebral ischemia. 1
Hypovolemic brain-injured patients do not tolerate transfer well, and hypotension adversely affects neurological outcomes. 1
Hypotension should be assumed to be due to hemorrhage in trauma with TBI, and bleeding must be controlled before transfer. 1
If fluid resuscitation is not needed, cautious use of isotonic fluids (normal saline) to maintain hydration while preventing volume overload is appropriate. 1
Special Considerations: Hypertonic Saline
While hypertonic saline solutions are used for acute ICP management, they are not recommended as primary resuscitation fluids. 1
Hypertonic saline (3% or 7.5%) is reserved for treating intracranial hypertension or signs of brain herniation, not routine fluid resuscitation. 1
Large prospective studies with 2,184 patients found no survival or neurological outcome benefit from out-of-hospital hypertonic saline resuscitation compared to normal saline. 1
Prophylactic hypertonic saline administration without evidence of intracranial hypertension was not superior to crystalloids for outcomes. 1
Common Pitfalls to Avoid
Using "balanced" crystalloids like Ringer's lactate because they appear isotonic by theoretical osmolarity—they are actually hypotonic by real osmolality and can worsen cerebral edema. 1
Administering colloids or albumin thinking they will provide better volume expansion—albumin specifically increases mortality in TBI, and other colloids are hypotonic. 1
Fluid restriction to prevent cerebral edema—excessive restriction may result in hypotension, which increases ICP and worsens neurological outcomes. 2
Permissive hypotension strategies used in hemorrhagic shock should only be considered in exceptional circumstances with TBI, as the brain requires adequate perfusion pressure. 1
Blood Pressure Management Adjuncts
After adequate fluid resuscitation with normal saline, if hypotension persists: