When would you administer D5NS (5% dextrose in normal saline) to an adult patient?

When to Administer D5NS to Adult Patients

D5NS (5% dextrose in normal saline) should be given to adult patients primarily in three clinical scenarios: (1) during adrenal crisis resuscitation alongside stress-dose steroids, (2) for maintenance fluid replacement in severe diarrhea when patients cannot tolerate oral intake, and (3) as a transition fluid in diabetic ketoacidosis once glucose falls below 250 mg/dL.

Primary Indications

Adrenal Insufficiency/Crisis

• Strongly consider a concomitant fluid bolus of 20 mL/kg of D5NS during the first hour of treatment when administering stress-dose hydrocortisone for adrenal crisis 1
• The dextrose component addresses potential hypoglycemia that commonly accompanies adrenal insufficiency, while the normal saline provides volume resuscitation and sodium replacement 1
• This combination is critical because adrenal crisis patients often present with both hypoglycemia and hypovolemia requiring simultaneous correction 1

Severe Diarrhea with Dehydration

• After initial isotonic crystalloid resuscitation for severe dehydration, if the patient is unable to drink, administer 5% dextrose 0.25 normal saline solution with 20 mEq/L potassium chloride intravenously for ongoing maintenance 1
• This recommendation comes from the 2017 IDSA guidelines for infectious diarrhea management, which specify this exact formulation for maintenance after acute resuscitation 1
• The dextrose prevents hypoglycemia during prolonged inability to take oral nutrition, while the hypotonic saline replaces ongoing gastrointestinal losses 1

Diabetic Ketoacidosis (Transition Phase)

• When serum glucose reaches 250 mg/dL during DKA treatment, switch from normal saline to D5 with 0.45-0.75% NaCl to prevent hypoglycemia while continuing insulin therapy to clear ketoacidosis 2
• This transition is essential because insulin must be continued to resolve ketoacidosis even after glucose normalizes, necessitating dextrose supplementation 2
• Note that D5NS specifically (rather than D5 half-normal saline) may be used when sodium levels are low-normal or the patient requires more aggressive sodium replacement 2

Important Clinical Context

What D5NS Provides

• Each liter contains 50 grams of dextrose (5 g per 100 mL) plus 154 mEq each of sodium and chloride 3
• This delivers both glucose supplementation and isotonic sodium replacement simultaneously 3, 2
• The tonicity is approximately 560 mOsm/L (300 from NaCl + 260 from dextrose initially, though dextrose is rapidly metabolized) 3

Critical Monitoring Requirements

• Monitor blood glucose hourly during acute resuscitation, then every 2-4 hours once stable to prevent both hyperglycemia and hypoglycemia 2
• Assess for signs of fluid overload, particularly in elderly patients or those with cardiac/renal disease 2
• The maximum rate at which dextrose can be infused without producing glycosuria is 0.5 g/kg/hour, with about 95% retention at 0.8 g/kg/hour 4

Common Pitfalls to Avoid

When NOT to Use D5NS

• Do not use dextrose-containing fluids during cardiac arrest resuscitation - this is associated with decreased survival and worse neurological outcomes 5
• Avoid in traumatic brain injury or neurosurgical patients where hypotonic solutions can worsen cerebral edema 2
• Do not use for routine elective surgery fluid replacement - even 500 mL causes significant transient hyperglycemia (>10 mmol/L in 72% of patients) without preventing hypoglycemia 6
• Avoid as initial resuscitation fluid in severe dehydration or shock - use isotonic crystalloids (normal saline or lactated Ringer's) first 1

Hyperglycemia Risk

• D5NS can cause significant hyperglycemia even in non-diabetic patients, with plasma glucose exceeding 10 mmol/L in 72% after just 500 mL 6
• In critically ill patients, hyperglycemia from dextrose-containing diluents and fluids can worsen outcomes 2
• Slow infusion of hypertonic dextrose solutions is essential to ensure proper utilization and avoid production of hyperglycemia 4

Electrolyte Considerations

• Using saline-based diluents and fluids (including D5NS) increases risk of hypernatremia and hyperchloremia compared to D5W 7
• When D5NS is used as a drug diluent in ICU patients, it accounts for approximately 21% of total infusion volume and significantly increases hypernatremia risk (adjusted OR 2.43) 7

Alternative Considerations

When to Use Other Dextrose Solutions Instead

• For hypernatremic dehydration, use 5% dextrose in water (D5W) alone rather than D5NS, as it prevents worsening hypernatremia 2
• For pediatric maintenance with hypoglycemia risk, use D10 normal saline to meet glucose requirements of 4-6 mg/kg/min 2
• For hypoglycemia treatment specifically, use concentrated dextrose (D10, D25, or D50) in 5-gram aliquots rather than maintenance fluids 8, 9