Why is Hartmann's (Ringer's lactate) solution or Sterofundin not used for bolus resuscitation in patients with traumatic brain injury (TBI)?

Why Hartmann's (Ringer's Lactate) and Sterofundin Are Avoided for Bolus Resuscitation in Traumatic Brain Injury

Hartmann's solution (Ringer's lactate) and Sterofundin should not be used for bolus resuscitation in patients with traumatic brain injury because they are hypotonic relative to plasma, which increases the risk of cerebral edema by promoting water movement from plasma into brain tissue, potentially worsening intracranial pressure and mortality. 1

The Osmolarity Problem

The fundamental issue is osmolarity and its direct impact on cerebral water content:

• Hartmann's/Ringer's lactate has an osmolarity of approximately 273 mOsm/L, making it hypotonic compared to normal plasma (280-295 mOsm/L) 1
• The osmolarity of administered intravenous fluids directly impacts water movement between plasma and brain tissue, cerebral water content, and risk of edema through rheological effects 1
• Hypotonic solutions promote water shift into the brain parenchyma, increasing intracranial pressure in patients who already have compromised intracranial compliance from TBI 1

Evidence-Based Guideline Recommendations

The strongest guideline evidence explicitly addresses this:

• The 2024 International Multidisciplinary Perioperative Quality Initiative recommends use of 0.9% saline as first-line fluid therapy in patients with traumatic brain injury (weak recommendation, moderate quality evidence) 1
• The 2013 European trauma guidelines state that hypotonic solutions such as Ringer's lactate should be avoided in patients with severe head trauma 1
• The primary goal for fluid therapy in neurosurgery and TBI is to maintain normal blood volume, optimize cerebral blood flow, and avoid reduction in plasma osmolarity 1

Clinical Outcomes Data

The mortality impact is significant:

• A retrospective study from the PROMMTT trial found that lactated Ringer's was associated with increased adjusted mortality compared with normal saline in patients with TBI (HR = 1.78, CI 1.04-3.04, p = 0.035) 2
• In patients without TBI, no mortality difference was demonstrated between fluid types (HR = 1.49, CI 0.757-2.95, p = 0.247) 2
• Positive fluid balance and higher fluid intake in TBI patients are associated with higher mortality and worse functional outcomes, as demonstrated in the CENTER-TBI and OzENTER-TBI cohorts 1

The Preferred Alternative: Normal Saline

Normal saline (0.9% NaCl) is recommended because:

• 0.9% saline has an osmolarity of 308 mOsm/L, making it isotonic to slightly hypertonic, which prevents water shift into brain tissue 1
• Normal saline is the crystalloid of choice for initial resuscitation and maintenance in brain injury to prevent cerebral edema from hypotonic fluids 3
• In trauma patients with TBI specifically, normal saline is preferred over balanced crystalloid solutions 4

Buffered Isotonic Solutions as an Alternative

There is emerging support for truly isotonic buffered solutions:

• Buffered isotonic solutions (such as Plasmalyte®) might be better than 0.9% saline as they are not associated with hyperchloremic metabolic acidosis or adverse renal effects 1
• The key distinction is that these solutions must be truly isotonic (not hypotonic like Hartmann's/Ringer's lactate) 1

Common Pitfalls to Avoid

• Do not assume all "balanced" crystalloids are safe in TBI—Hartmann's/Ringer's lactate are hypotonic despite being "balanced" in electrolyte composition 1
• Do not use Hartmann's/Ringer's lactate even if the patient is hypovolemic from trauma—the risk of cerebral edema outweighs resuscitation benefits in TBI patients 1
• Avoid excessive fluid administration and positive fluid balance in TBI patients regardless of fluid type, as this independently worsens outcomes 1
• Never use albumin for resuscitation in TBI patients, as it increases mortality (strong recommendation, moderate quality evidence) 1, 5

Special Consideration: Hypertonic Saline

For specific indications in TBI:

• Hypertonic saline (3% or 7.5%) is used as osmotherapy to treat elevated intracranial pressure, not for routine volume resuscitation 6, 7
• Prehospital bolus of 7.5% hypertonic saline in severe TBI did not improve mortality or neurological outcomes at 6 months compared to Ringer's lactate in a randomized trial 8
• Hypertonic saline should be reserved for acute ICP crises as bolus therapy, not for sustained volume resuscitation 3