When should a patient be switched from D5LR (5% dextrose in lactated Ringer's solution) to PNSS (0.9% sodium chloride solution or normal saline)?

When to Switch from D5LR to PNSS

Switch from D5LR (5% dextrose in lactated Ringer's) to PNSS (0.9% normal saline) immediately if the patient develops or has severe traumatic brain injury, increased intracranial pressure, or signs of cerebral edema, as lactated Ringer's is hypotonic (273-277 mOsm/L) and can worsen brain swelling. 1

Primary Indication for Switching: Neurological Deterioration

Severe Head Trauma or Traumatic Brain Injury (TBI)

• Lactated Ringer's solution should be avoided in patients with severe head trauma because it is hypotonic when measured by real osmolality rather than theoretical osmolality 1
• The hypotonic nature of LR can increase cerebral edema and worsen intracranial pressure 1, 2
• Normal saline (308 mOsm/L) is the isotonic crystalloid of choice for brain-injured patients 1
• Switch immediately if patient develops focal neurological signs, declining Glasgow Coma Scale, or imaging shows cerebral edema 3, 1

Secondary Indications for Switching

Rhabdomyolysis or Crush Syndrome

• Avoid Ringer's lactate in suspected or proven rhabdomyolysis/crush syndrome due to its potassium content (4 mmol/L) 1
• Potassium levels may increase markedly following reperfusion of crushed limbs, making the baseline potassium in LR problematic 1
• Switch to PNSS if creatine kinase is markedly elevated or crush injury is identified 1

Hyperglycemia Management

• The dextrose component in D5LR can cause significant hyperglycemia, with plasma glucose exceeding 10 mmol/L in 72% of patients receiving dextrose-containing solutions 4
• Switch to PNSS (without dextrose) if blood glucose rises above 10 mmol/L or patient develops hyperglycemia 5, 4
• This is particularly important in surgical patients where hyperglycemia may impair wound healing 4

Hyperchloremic Metabolic Acidosis Concerns

• While PNSS can cause hyperchloremic acidosis with large volumes, this is a consideration for not switching to PNSS rather than a reason to switch 2, 6
• If switching to PNSS is necessary (for TBI), limit volume to maximum 1-1.5 liters to minimize hyperchloremic effects 2, 6

When NOT to Switch (Continue D5LR)

General Fluid Resuscitation

• Balanced crystalloids like lactated Ringer's are superior to normal saline for reducing mortality and adverse renal events in most clinical scenarios 6, 7
• Continue D5LR for general trauma resuscitation (without severe TBI), perioperative fluid management, sepsis, and critical illness 1
• The SMART trial demonstrated that balanced crystalloids reduce major adverse kidney events compared to normal saline 2

Mild-to-Moderate Hyperkalemia or Renal Dysfunction

• The potassium content in LR (4 mmol/L) should not be considered a contraindication in patients with mild-to-moderate hyperkalemia or renal dysfunction 1
• Large randomized studies involving 30,000 patients found comparable plasma potassium concentrations between balanced fluids and normal saline 1

Clinical Decision Algorithm

1. Assess neurological status: If severe TBI, increased ICP, or focal neurological signs → Switch to PNSS immediately 1

2. Check for crush injury/rhabdomyolysis: If CK markedly elevated or crush syndrome suspected → Switch to PNSS 1

3. Monitor blood glucose: If glucose >10 mmol/L → Switch to plain LR or PNSS (without dextrose) 5, 4

4. If none of the above: Continue D5LR as balanced crystalloids are superior for most clinical scenarios 1, 2, 6

Common Pitfalls

• Do not switch based solely on potassium concerns: The 4 mmol/L potassium in LR is physiological and does not cause hyperkalemia in most patients, even with renal impairment 1
• Avoid prolonged hypoglycemia concerns: Patients fasting for surgery do not develop hypoglycemia even after 11-13 hours of fasting, so dextrose is not required to prevent hypoglycemia 5, 4
• Remember PNSS limitations: If switching to PNSS for TBI, be aware that large volumes cause hyperchloremic acidosis and should be limited to 1-1.5L maximum 2, 6
• Monitor chloride levels: If using PNSS, check chloride levels as hyperchloremia (>110 mEq/L) is associated with increased mortality and worsening renal function 2