Balanced Crystalloids Should Be Preferred Over Normal Saline for Fluid Resuscitation
Balanced crystalloid solutions (such as Lactated Ringer's or Plasma-Lyte) should be used in preference to 0.9% normal saline for resuscitation and maintenance of intravascular volume in critically ill patients, with the important exception of traumatic brain injury patients. 1, 2, 3
Primary Recommendation for Most Clinical Scenarios
Balanced crystalloids reduce mortality and major adverse kidney events compared to normal saline in critically ill patients, particularly those with sepsis or requiring emergency surgery 1, 2
The SMART trial and subsequent meta-analyses demonstrated that balanced crystalloids are associated with lower 30-day mortality (OR 0.84,95% CI 0.74-0.95) and reduced major renal events in sepsis patients 1
The SALT trial showed that crystalloid solutions resulted in lower 30-day in-hospital mortality and reduced need for renal replacement therapy compared to 0.9% saline 1
Physiological Rationale
Normal saline contains supraphysiologic chloride concentration (154 mmol/L) which causes hyperchloremic metabolic acidosis, decreased kidney perfusion, reduced urine output, and increased extravascular fluid accumulation 2, 3, 4
Balanced solutions contain physiological or near-physiological chloride concentrations, preventing worsening of acidosis and improving acid-base balance 2, 3
If normal saline must be used, limit administration to a maximum of 1-1.5 L to minimize chloride load and metabolic complications 2, 3
Critical Exception: Traumatic Brain Injury
In patients with traumatic brain injury (TBI), normal saline is preferred over balanced crystalloids 5
Balanced solutions were associated with increased mortality in TBI patients (OR 1.31,95% CI 1.03-1.65) compared to normal saline 5
Hypotonic balanced solutions should be avoided in severe head trauma to prevent fluid shift into damaged cerebral tissue and cerebral edema 2, 3
Specific Clinical Applications
Sepsis and Septic Shock
- Balanced crystalloids are strongly recommended as first-line fluid therapy 1
- Benefits are most pronounced when balanced crystalloids are initiated in the emergency department rather than delayed until ICU admission 1
Emergency Laparotomy and Surgical Patients
- Balanced crystalloids should be used for resuscitation and intravascular volume maintenance 1
- The use of 0.9% saline should be limited, especially in high-risk patients with existing electrolyte derangements such as acidosis or hyperchloremia 1
Hemorrhagic Shock
- Balanced crystalloids are favored as the initial crystalloid solution over colloids 1
- Colloid solutions (hydroxyethyl starches, gelatins) are not recommended due to lack of mortality benefit and increased risk of renal complications 1
Common Pitfalls to Avoid
Do not use large volumes of normal saline (>5000 mL) as this has been associated with increased mortality in observational studies 2
Avoid assuming all balanced solutions are equivalent - Lactated Ringer's and Plasma-Lyte have slightly different compositions, though both are superior to normal saline in most scenarios 3, 4
Do not reflexively use normal saline for blood product administration - Plasma-Lyte A is FDA-approved for use with blood components and may be safer than normal saline 4
Monitoring Requirements
Monitor serum electrolytes, particularly chloride levels, in patients receiving large-volume resuscitation 3
Assess acid-base status in critically ill patients receiving substantial fluid volumes 3
Watch for signs of hyperchloremic metabolic acidosis (elevated chloride, normal anion gap acidosis) when normal saline has been administered 2, 4