What is the recommended crystalloid to blood loss ratio?

Recommended Crystalloid to Blood Loss Ratio

For initial fluid resuscitation in trauma and hemorrhagic shock, a crystalloid to blood loss ratio of 1.5:1 is recommended as the most effective approach based on current evidence. 1, 2

Crystalloid vs. Colloid Considerations

• Crystalloid solutions are the preferred first-line fluid for initial resuscitation in hypovolemic patients due to similar clinical outcomes with lower cost compared to colloids 2
• Balanced crystalloids (such as Ringer's Lactate) are generally preferred over 0.9% sodium chloride to reduce the risk of hyperchloremic acidosis and renal dysfunction 1
• If 0.9% sodium chloride is used, it should be limited to a maximum of 1-1.5 L 1
• Colloid solutions can achieve similar hemodynamic endpoints with lower fluid volumes compared to crystalloids, with a volume ratio of crystalloid to colloid of approximately 1.5:1 1, 2

Blood Loss Replacement Strategy

• For blood loss up to 20-25% of total blood volume, balanced crystalloid solutions alone are typically sufficient 3
• For blood loss exceeding 20-25% of total blood volume or when hematocrit falls below 20%, consider adding colloids or blood products 3
• If erythrocyte transfusion becomes necessary, target a hemoglobin level of 70-90 g/L 1

Specific Fluid Resuscitation Approach

• Initial fluid bolus should be 10-20 ml/kg of balanced crystalloid 2
• Implement a restricted volume replacement strategy with permissive hypotension (systolic BP 80-90 mmHg) in trauma patients without traumatic brain injury until bleeding is controlled 4
• For patients with traumatic brain injury, avoid hypotonic solutions like Ringer's lactate to prevent fluid shift into damaged cerebral tissue 1
• Recent evidence suggests that a 1:1 crystalloid to blood loss ratio may be adequate for maintaining hemodynamic stability while avoiding pulmonary edema, challenging the historical 3:1 ratio 5

Important Considerations and Pitfalls

• Aggressive crystalloid resuscitation can increase hydrostatic pressure on wounds, dislodge blood clots, and dilute coagulation factors 4
• Large-volume fluid administration increases the risk of coagulopathy and tissue edema 4
• Synthetic colloids (hydroxyethyl starches) should be avoided due to increased risk of renal failure and coagulation disorders 2
• Continually reassess the patient's response to fluid therapy using dynamic variables (pulse pressure variation, stroke volume variation) and clinical signs of tissue perfusion 2

Special Circumstances

• In patients with severe ongoing bleeding, if crystalloids combined with vasopressors are unable to maintain basic tissue perfusion, consider colloid infusions as a further option 1
• For elderly patients and those with traumatic brain injury or spinal cord injury, permissive hypotension may not be well tolerated, requiring higher blood pressure targets 4