What is Plasma-Lyte?
Plasma-Lyte is a balanced isotonic crystalloid solution that closely mimics human plasma composition and is recommended as first-line fluid therapy for most critically ill patients, including those with sepsis, trauma (excluding severe traumatic brain injury), hemorrhagic shock, and perioperative settings. 1
Composition and Characteristics
Plasma-Lyte contains the following electrolytes that approximate physiological plasma concentrations 1, 2, 3:
- Sodium: 140 mEq/L
- Potassium: 5 mEq/L
- Chloride: 98 mEq/L (significantly lower than normal saline's 154 mEq/L)
- Magnesium: 3 mEq/L
- Acetate: 27 mEq/L (serves as a buffer, converted to bicarbonate)
- Osmolarity: 294 mOsm/L (isotonic, range 280-310 mOsm/L)
- Glucose: 0 g/dL 2
The balanced electrolyte composition, particularly the lower chloride content and physiologic sodium-to-chloride ratio, distinguishes Plasma-Lyte from normal saline and provides metabolic advantages 1, 3.
Primary Clinical Uses
General Fluid Resuscitation and Maintenance
Plasma-Lyte should be used as the default choice for IV fluid therapy across most clinical scenarios because it maintains electrolyte compositions closer to plasma and consistently demonstrates superior outcomes compared to normal saline 1. It is appropriate for both volume resuscitation and maintenance fluid therapy 2, 3.
Trauma and Hemorrhagic Shock
In hemorrhagic shock and general trauma resuscitation (excluding severe traumatic brain injury), Plasma-Lyte should be used as first-line fluid therapy to reduce mortality and adverse renal events 1. A randomized trial in trauma patients demonstrated that Plasma-Lyte resulted in significantly greater improvement in base excess (7.5 vs 4.4 mmol/L), higher arterial pH (7.41 vs 7.37), and lower serum chloride (104 vs 111 mEq/L) at 24 hours compared to normal saline 4. Plasma-Lyte avoids hyperchloremic metabolic acidosis associated with large volumes of normal saline, which can impair renal function and coagulation 1.
Sepsis and Critical Illness
In sepsis-induced hypoperfusion, at least 30 mL/kg of balanced crystalloid (including Plasma-Lyte) should be administered within the first 3 hours 1. The SMART trial involving 15,802 ICU patients demonstrated that balanced crystalloids (including Plasma-Lyte) reduced the incidence of major adverse kidney events by 1.1% absolute risk reduction compared to normal saline 5, 1. The SALT trial showed lower 30-day in-hospital mortality and reduced need for renal replacement therapy with balanced crystalloids 5.
Perioperative and Surgical Settings
Plasma-Lyte should be used as the primary intraoperative fluid, particularly in patients with end-stage renal disease or those undergoing major surgery 1. Balanced crystalloids should be used in preference to 0.9% normal saline for resuscitation and to maintain intravascular volume during emergency laparotomy 5. In kidney transplant recipients, balanced crystalloids like Plasma-Lyte reduce delayed graft function compared to normal saline 1.
Acute Kidney Injury
Plasma-Lyte is appropriate and recommended for patients with acute kidney injury, with the critical exception of patients with severe traumatic brain injury 1. The potassium content (5 mEq/L) in Plasma-Lyte should not be considered a contraindication in patients with mild-to-moderate hyperkalemia or renal dysfunction, except in rhabdomyolysis/crush syndrome 1. Large randomized studies involving 30,000 patients found comparable plasma potassium concentrations between groups receiving balanced fluids (containing 4-5 mmol/L potassium) versus normal saline 1.
Critical Contraindications
Plasma-Lyte should be avoided in two specific scenarios:
Severe traumatic brain injury or acute brain injury: In patients with acute brain injury requiring isotonic crystalloids, 0.9% NaCl is the preferred first-line choice to prevent cerebral edema 5, 1. Isotonic crystalloids (osmolarity 280-310 mOsm/L) are recommended, and while Plasma-Lyte is technically isotonic, guidelines specifically favor 0.9% NaCl in this population 5.
Rhabdomyolysis or crush syndrome: Plasma-Lyte should be avoided due to its potassium content (5 mEq/L) in patients with suspected or proven rhabdomyolysis 1.
Metabolic and Physiological Advantages
Plasma-Lyte prevents hyperchloremic acidosis and maintains renal perfusion, reducing major adverse kidney events compared to normal saline 1, 6. The balanced electrolyte composition makes it physiologically more similar to plasma than 0.9% NaCl, with a Na+:Cl- ratio that more closely resembles plasma 1, 3. The acetate buffer is converted to bicarbonate, providing additional buffer capacity to address acidosis 3.
A pilot randomized controlled trial in critically ill patients showed that Plasma-Lyte significantly decreased peak chloride concentrations (108 vs 111 mmol/L) compared to normal saline, though base excess differences were not statistically significant 7.
Practical Implementation Algorithm
For hypotensive patients requiring resuscitation:
- If severe traumatic brain injury or increased intracranial pressure is present: Use 0.9% NaCl 5, 1
- For all other scenarios (general trauma, sepsis, perioperative, AKI, burns): Use Plasma-Lyte as first-line 1, 6
- Administer in 500 mL boluses and reassess hemodynamics frequently 1
- Monitor chloride and acid-base status with large volume resuscitation 1
Important Caveats
When glucose administration is needed alongside Plasma-Lyte, separate dextrose-containing solutions must be administered, as Plasma-Lyte contains no glucose 2. For pediatric patients requiring both isotonic fluids and dextrose, clinicians must use alternative solutions since Plasma-Lyte with dextrose is not available in the US 2.
Plasma-Lyte shares common crystalloid limitations including potential for fluid overload, edema with weight gain, pulmonary edema, and worsening of intracranial pressure 3. The magnesium content may theoretically affect peripheral vascular resistance and heart rate, though clinical significance remains unclear 3.