What is the composition of Sterofundin (balanced electrolyte solution) and its clinical indications?

Sterofundin Composition and Clinical Indications

Composition of Sterofundin ISO®

Sterofundin ISO® is a balanced isotonic crystalloid solution containing sodium 127 mmol/L, potassium 4 mmol/L, chloride 127 mmol/L, calcium 0.9 mmol/L, magnesium 1 mmol/L, and acetate/malate as organic anions, with an osmolarity of approximately 273-277 mOsm/L. 1, 2, 3

• The sodium-to-chloride ratio is approximately 1:1 (127:127 mmol/L), which is higher in chloride content than plasma but lower than normal saline (154 mmol/L). 2, 3
• The potassium content of 4 mmol/L approximates normal plasma levels and does not pose hyperkalemia risk in most patients. 1, 3
• Organic anions (acetate and malate) replace some chloride to create a more balanced solution compared to normal saline, though it contains more chloride than other balanced solutions like Plasma-Lyte (106 mmol/L). 2
• The osmolarity of 273-277 mOsm/L makes Sterofundin slightly hypotonic compared to plasma (275-295 mOsm/L). 4

Primary Clinical Indications

Sterofundin is indicated as an isotonic maintenance and resuscitation fluid for pediatric and adult patients undergoing surgery or requiring intravenous fluid therapy, with the critical exception of patients with severe traumatic brain injury. 5, 1, 3

Pediatric Surgery and Maintenance Fluid Therapy

• Use Sterofundin (with 1% glucose added) as the preferred intraoperative fluid for children aged 1-36 months undergoing major surgery, as it reduces the risk of hyperchloremic acidosis compared to normal saline. 1
• European pediatric guidelines recommend balanced isotonic solutions like Sterofundin for intravenous maintenance fluid therapy in acute and critically ill children to prevent hyponatremia and metabolic complications. 5
• When large volumes exceed approximately 47 mL/kg, even Sterofundin can cause hyperchloremia, though the risk is lower than with normal saline. 1

Adult Neurosurgery (Non-TBI Cases)

• Sterofundin provides superior acid-base control compared to normal saline during elective craniotomy for non-traumatic conditions (e.g., sellar region tumors), preventing metabolic acidosis and maintaining stable sodium and chloride levels. 3, 6
• In elective neurosurgery patients, normal saline caused pH <7.35 in 27.7% and base excess <-4.0 in 33.3% of patients, whereas Sterofundin maintained normal acid-base balance. 3

Correction of Hypernatremia and Metabolic Alkalosis

• Sterofundin is effective for correcting hypernatremia in neurosurgical patients with sellar region tumors, providing gradual sodium reduction without the risk of rapid overcorrection seen with hypotonic solutions. 6
• Sterofundin also corrects metabolic alkalosis more effectively than normal saline or other balanced solutions in this population. 6

Absolute Contraindications

Never use Sterofundin in patients with severe traumatic brain injury, closed head injury, or increased intracranial pressure, because its hypotonic osmolarity (273-277 mOsm/L) will worsen cerebral edema and increase intracranial pressure; use 0.9% normal saline (308 mOsm/L) instead. 4

• The distinction between theoretical and real osmolality is critical: Sterofundin appears nearly isotonic by calculation but is functionally hypotonic, driving water into brain tissue. 4
• This contraindication applies to both resuscitation and maintenance infusions in TBI patients. 4

Additional Contraindications

• Avoid Sterofundin in rhabdomyolysis or crush syndrome due to its potassium content (4 mmol/L), which poses additional risk when tissue reperfusion releases intracellular potassium. 4
• Do not use in patients with severe hyperkalemia (K⁺ >6.5 mmol/L) until potassium normalizes. 7

Comparative Advantages Over Normal Saline

Sterofundin prevents hyperchloremic metabolic acidosis that occurs with large-volume normal saline administration, making it safer for prolonged or high-volume fluid therapy in non-TBI patients. 1, 2, 3

• In pediatric craniofacial surgery, Sterofundin caused hyperchloremic acidosis in 19/50 patients (38%), whereas the lower-chloride solution Deltajonin® (106 mmol/L chloride) caused acidosis in only 2/50 patients (4%), indicating that Sterofundin's 127 mmol/L chloride content still carries some acidosis risk with large volumes. 2
• Despite this, Sterofundin remains superior to normal saline (154 mmol/L chloride) for maintaining acid-base balance during surgery. 1, 3

Clinical Decision Algorithm

Step 1: Screen for Absolute Contraindications

• If severe TBI, closed head injury, or GCS <13: Use 0.9% normal saline exclusively. 4
• If rhabdomyolysis or crush syndrome: Use potassium-free crystalloid (normal saline). 4
• If serum K⁺ >6.5 mmol/L: Use normal saline until hyperkalemia resolves. 7

Step 2: Select Sterofundin for Appropriate Scenarios

• Pediatric surgery (age 1-36 months): Use Sterofundin + 1% glucose at 1-2 mL/kg/h intraoperatively. 1
• Elective adult neurosurgery (non-trauma): Use Sterofundin for maintenance and replacement. 3
• Hypernatremia correction: Use Sterofundin for gradual sodium reduction. 6

Step 3: Monitor for Complications

• When total volume exceeds 47 mL/kg in children or equivalent large volumes in adults, monitor serum chloride, pH, and base excess every 2-4 hours to detect hyperchloremic acidosis. 1, 2
• Check sodium levels during hypernatremia correction to avoid overly rapid reduction. 6

Important Caveats

• Sterofundin's chloride content (127 mmol/L) is intermediate between normal saline (154 mmol/L) and lower-chloride balanced solutions like Plasma-Lyte or Deltajonin® (106 mmol/L), so it still carries some risk of hyperchloremic acidosis with very large volumes. 2
• The slight hypotonicity (273-277 mOsm/L) is clinically insignificant in non-brain-injured patients but is absolutely contraindicated in TBI. 4
• Always add 1% glucose to Sterofundin for pediatric maintenance to prevent hypoglycemia, though hypoglycemia occurred in only 2/229 patients in one study. 1