Are there any contraindications to using lactated Ringer's solution as the initial fluid in a patient with a closed head injury?

Lactated Ringer's Solution Should Be Avoided in Closed Head Injury

Yes, there is a clear contraindication to using lactated Ringer's (LR) solution in patients with closed head injury or traumatic brain injury (TBI), and 0.9% normal saline should be used instead as the isotonic crystalloid of choice. 1, 2

Primary Contraindication: Hypotonic Nature and Cerebral Edema Risk

The fundamental problem with LR in head trauma is its hypotonic osmolality when measured by real osmolality (mosmol/kg) rather than theoretical osmolality (mosmol/L), which can worsen cerebral edema and increase intracranial pressure. 1, 2

Key Physiological Concerns:

• LR has an osmolarity of 273-277 mOsm/L, making it hypotonic compared to plasma (275-295 mOsm/L), and this hypotonicity drives water movement into brain tissue, exacerbating cerebral edema. 1, 2

• Multiple guidelines explicitly state that gelatins, Ringer's lactate, and Ringer's acetate are hypotonic when real osmolality is determined and should be avoided in brain injury. 1

• 0.9% saline is the only commonly available isotonic crystalloid solution (osmolarity 308 mOsm/L) and is therefore the current crystalloid of choice in brain injury. 1, 2

Clinical Evidence Supporting This Recommendation

Observational Data:

• A large prospective multicenter trauma study (PROMMTT) demonstrated that pre-hospital LR was associated with higher adjusted mortality in TBI patients (HR = 1.78,95% CI 1.04-3.04, p = 0.035) compared to normal saline. 3 This finding was specific to patients with TBI (AIS head ≥3), while no mortality difference was seen in non-TBI trauma patients. 3

Randomized Controlled Trial Evidence:

• A prospective RCT in 32 severely head-injured children (Glasgow Coma Score <8) compared LR to hypertonic saline and found that LR-treated patients required significantly more interventions to control ICP, had higher rates of acute respiratory distress syndrome, longer ICU stays (11.6 vs 8.0 days, p=0.04), and longer mechanical ventilation times. 4

• Animal model studies consistently demonstrate that rapid infusion of LR after closed head trauma increases intracranial pressure significantly more than hypertonic solutions (9.5 vs 1.7 mm Hg increase, p<0.001). 5

• Even in rat models, LR administration after closed head trauma showed no deleterious effect on brain edema or neurological outcome, but this was in the context of small volumes (0.25 ml/g) and does not translate to clinical practice where larger resuscitation volumes are often needed. 6

Clinical Algorithm for Fluid Selection in Head Trauma

Step 1: Identify Severe TBI

• Any patient with closed head injury, suspected increased intracranial pressure, or Glasgow Coma Score <13 should be considered to have severe TBI requiring isotonic fluid management. 1, 2

Step 2: Choose Appropriate Crystalloid

• Use 0.9% normal saline as the primary resuscitation and maintenance fluid. 1, 2
• Avoid all hypotonic solutions including LR, Ringer's acetate, and gelatins. 1

Step 3: Fluid Management Goals

• Reverse hypovolemia and avoid hypotension (hypotension adversely affects neurological outcome), but use cautious isotonic fluid administration to maintain hydration while preventing volume overload. 1
• Maintain mean arterial pressure with vasopressors (metaraminol or noradrenaline) after correcting hypovolemia, rather than excessive crystalloid administration. 1

Step 4: Monitor and Adjust

• Measure arterial blood pressure with transducer at the level of the tragus (including when head-up positioned). 1
• Target cerebral perfusion pressure maintenance while minimizing ICP elevation. 1

Common Pitfalls and Caveats

Pitfall 1: Assuming "Balanced" Means "Better"

• While balanced crystalloids like LR are superior to normal saline in most clinical scenarios (sepsis, general trauma without TBI, perioperative management), this advantage is completely reversed in TBI where the hypotonic nature becomes the dominant concern. 2, 7

Pitfall 2: Ignoring the Osmolality Difference

• The difference between theoretical osmolality (mosmol/L) and real osmolality (mosmol/kg) is clinically significant in brain injury—LR appears "nearly isotonic" by theoretical calculation but is functionally hypotonic. 1, 2

Pitfall 3: Polytrauma Patients

• In patients with both TBI and hemorrhagic shock, the TBI contraindication takes precedence—use normal saline for initial resuscitation, limiting volume to 1-1.5 L maximum before transitioning to blood products. 1, 2
• Correction of major hemorrhage takes precedence over transfer, but fluid choice should still respect the TBI contraindication. 1

Pitfall 4: Maintenance Fluids

• The contraindication applies to both resuscitation AND maintenance fluids—even "maintenance rate" LR can contribute to cerebral edema over hours in TBI patients. 1, 2

Additional Contraindications for LR (Beyond TBI)

• Rhabdomyolysis or crush syndrome: The 4 mmol/L potassium content in LR poses additional risk when potassium levels increase markedly following reperfusion of crushed tissue. 2, 8

• Active severe hyperkalemia (>6.5 mmol/L): Avoid potassium-containing solutions until hyperkalemia resolves. 2

When LR Is Appropriate (For Context)

To emphasize the specificity of this contraindication, LR remains the preferred first-line crystalloid for most other trauma scenarios including general trauma without TBI, sepsis, burns, perioperative management, and even acute kidney injury. 2, 7 The TBI contraindication is an important exception to the general superiority of balanced crystalloids over normal saline.