From the Guidelines
Balanced crystalloids are the preferred choice for fluid resuscitation in critically ill patients, including those with sepsis or septic shock, due to their ability to maintain normal acid-base status and minimize hyperchloremic metabolic acidosis 1.
Definition and Composition
Balanced crystalloids are intravenous fluids that closely mimic the electrolyte composition of human plasma, containing sodium, chloride, potassium, and often calcium and magnesium, with a balanced anion composition that helps maintain normal acid-base status. Common examples include Lactated Ringer's solution, Plasma-Lyte, and Hartmann's solution.
Benefits and Recommendations
These fluids typically have a lower chloride concentration than normal saline (0.9% NaCl) and include buffers like lactate, acetate, or gluconate that metabolize to bicarbonate. The Surviving Sepsis Campaign guidelines suggest using either balanced crystalloids or saline for fluid resuscitation of patients with sepsis or septic shock, although the recommendation for balanced crystalloids is weaker due to low quality of evidence 1. However, more recent studies support the use of balanced crystalloids over normal saline due to their potential to reduce major adverse kidney events and improve acid-base balance 1.
Administration and Clinical Considerations
When administering balanced crystalloids, typical infusion rates range from maintenance rates (1-3 mL/kg/hr) to bolus administration (10-30 mL/kg) depending on the clinical situation. The physiological electrolyte profile of these solutions helps minimize iatrogenic electrolyte and acid-base disturbances that can occur with large-volume administration of unbalanced solutions like normal saline. Key considerations in the choice of fluid include the patient's volume status, electrolyte balance, and kidney function, as well as the potential for large-volume resuscitation 1.
Key Points
- Balanced crystalloids are preferred for most fluid resuscitation scenarios and maintenance fluid therapy.
- They cause less hyperchloremic metabolic acidosis compared to normal saline.
- Typical infusion rates range from 1-3 mL/kg/hr to bolus administration of 10-30 mL/kg.
- The choice of fluid should consider the patient's volume status, electrolyte balance, and kidney function.
From the Research
Definition of Balanced Crystalloids
- Balanced crystalloids are solutions that have a sodium, potassium, and chloride content closer to that of extracellular fluid 2
- They are designed to have fewer adverse effects on acid-base balance compared to unbalanced solutions like normal saline 2
Characteristics of Balanced Crystalloids
- Have a composition similar to that of human plasma 3
- Contain electrolytes such as sodium, potassium, and chloride in concentrations similar to those found in human blood 2
- Examples of balanced crystalloids include lactated Ringer's, Plasma-Lyte, and Hartmann's solution 3
Comparison with Unbalanced Crystalloids
- Normal saline (0.9% sodium chloride) is an example of an unbalanced crystalloid that can cause hyperchloremic metabolic acidosis and other adverse effects 4, 2
- Balanced crystalloids such as Plasma-Lyte have been shown to result in lower serum concentrations of chloride and lactate, and higher base excess compared to other balanced crystalloids 3
Clinical Use of Balanced Crystalloids
- Balanced crystalloids are used for volume replacement and resuscitation in critically ill patients 2, 5
- They may reduce the risk of complications such as acute kidney injury and death compared to unbalanced crystalloids like normal saline 2
- However, more research is needed to fully understand the benefits and risks of balanced crystalloids in different clinical settings 3, 2