What is the fluid of choice for intravenous (IV) resuscitation?

Fluid of Choice for IV Resuscitation

Balanced crystalloid solutions (Ringer's Lactate or Plasmalyte) are the preferred fluids for intravenous resuscitation in most clinical scenarios, as they are associated with better acid-base balance, reduced mortality, and fewer adverse renal events compared to 0.9% normal saline. 1, 2

Primary Recommendation

• Use balanced crystalloids (Ringer's Lactate or Plasmalyte) as first-line therapy for IV resuscitation in critically ill patients 1, 2
• These solutions have electrolyte compositions closer to plasma (sodium 130-145 mmol/L, chloride 98-127 mmol/L) compared to 0.9% saline (sodium 154 mmol/L, chloride 154 mmol/L) 1
• Balanced solutions maintain better acid-base balance and reduce the risk of hyperchloremic metabolic acidosis, particularly when large volumes are administered 1

Evidence Supporting Balanced Crystalloids

The most recent and highest quality evidence demonstrates clear benefits:

• In sepsis-induced hypotension, lactated Ringer's solution reduced mortality (12.2% vs 15.9%, adjusted HR 0.71, p=0.043) and increased hospital-free days compared to 0.9% saline 3
• In the SMART study involving 15,802 ICU patients, balanced solutions reduced major adverse kidney events (death, doubling of creatinine, or renal replacement therapy within 30 days) 1
• Balanced solutions consistently demonstrate superior acid-base balance without increasing transfusion requirements or complications 1

Fluids to Avoid

Synthetic colloids (hydroxyethyl starch, gelatin) should NOT be used due to:

• Increased risk of renal failure requiring replacement therapy 1
• Hemostasis disorders and higher bleeding risk 1
• Higher transfusion requirements without improved mortality 1

Albumin is NOT recommended for routine resuscitation due to higher cost without demonstrated mortality benefit over crystalloids 1, 2

Hypertonic saline (3% or 7.5%) should NOT be used as first-line therapy as it shows no mortality benefit in resuscitation (RR 0.96,95% CI 0.82-1.12) 1

Addressing the Potassium Concern

A common pitfall is avoiding balanced solutions due to their potassium content (4-5 mmol/L):

• The potassium in balanced solutions does NOT cause clinically significant hyperkalemia, even in patients prone to elevated potassium 1, 4
• Studies in renal transplant recipients showed potassium levels increased MORE with 0.9% saline than with Ringer's Lactate 1
• Two large randomized studies involving 30,000 patients found comparable plasma potassium concentrations between balanced solutions and 0.9% saline 1
• Physiologically, a fluid with potassium concentration lower than the patient's plasma cannot create potassium excess 1

Clinical Algorithm for Fluid Selection

Step 1: Identify the clinical scenario

• Sepsis, trauma, hemorrhagic shock, perioperative resuscitation, or general volume depletion 1, 2

Step 2: Choose balanced crystalloid as default

• Ringer's Lactate or Plasmalyte for all scenarios except traumatic brain injury with focal neurological signs 1, 2

Step 3: Special exception for severe TBI

• If traumatic brain injury with focal neurological signs AND hemorrhagic shock: consider hypertonic saline bolus for osmotic effect, then transition to balanced crystalloid 1, 2
• Note: One study showed increased mortality with pre-hospital lactated Ringer's in isolated TBI (HR 1.78, p=0.035), though this requires confirmation 5

Step 4: Avoid 0.9% saline except when

• No alternative is available
• Specific contraindication to balanced solutions exists (extremely rare)

Volume and Administration

• For sepsis-induced hypoperfusion: administer at least 30 mL/kg within the first 3 hours 2
• Use goal-directed therapy with frequent reassessment to prevent fluid overload 2
• Monitor dynamic variables (pulse pressure variation, stroke volume variation) rather than static variables (central venous pressure) to predict fluid responsiveness 2

Common Pitfalls to Avoid

• Do NOT use 0.9% saline for large-volume resuscitation (>5000 mL), as this causes hyperchloremic metabolic acidosis and is associated with increased mortality 1
• Do NOT withhold balanced solutions due to potassium content—this concern is not supported by evidence 1, 4
• Do NOT use synthetic colloids—they increase renal failure risk without improving outcomes 1
• Do NOT continue fluid administration without reassessment—fluid overload worsens outcomes and increases mortality 2