What is the fluid management strategy for Hyperosmolar Hyperglycemic State (HHS)?

Fluid Management Strategy for Hyperosmolar Hyperglycemic State (HHS)

The fluid management strategy for HHS should begin with isotonic saline (0.9% NaCl) at 15-20 ml/kg/h for the first hour to expand intravascular volume and restore renal perfusion, followed by adjustment of fluid choice based on corrected serum sodium levels and hemodynamic status. 1, 2

Initial Assessment and Diagnosis

• HHS is diagnosed by blood glucose >600 mg/dl, arterial pH >7.3, bicarbonate >15 mEq/l, minimal ketonuria/ketonemia, and effective serum osmolality >320 mOsm/kg H₂O 1, 2
• Calculate effective serum osmolality using the formula: 2[measured Na (mEq/l)] + glucose (mg/dl)/18 to guide fluid management decisions 1, 3
• Correct serum sodium for hyperglycemia by adding 1.6 mEq to sodium value for each 100 mg/dl glucose >100 mg/dl 3, 2

Fluid Resuscitation Protocol

Phase 1: Initial Resuscitation (First Hour)

• Administer isotonic saline (0.9% NaCl) at 15-20 ml/kg/h (approximately 1-1.5 L in average adult) to expand intravascular volume and restore renal perfusion 1, 2
• This rapid initial fluid replacement is critical to improve hemodynamic stability and organ perfusion 2

Phase 2: Subsequent Fluid Management

• After initial resuscitation, adjust fluid choice based on corrected serum sodium and hemodynamic status 1:
  • If corrected serum sodium is normal or elevated: Use 0.45% NaCl at 4-14 ml/kg/h 1, 3
  • If corrected serum sodium is low: Continue 0.9% NaCl at similar rate 1
• Once glucose falls below 300 mg/dl, add 5-10% dextrose to IV fluids while continuing to treat hyperosmolarity 2, 4

Phase 3: Electrolyte Management

• Once renal function is assured and serum potassium is known, add 20-30 mEq/L potassium (2/3 KCl and 1/3 KPO₄) to the infusion 1, 2
• Monitor electrolytes (sodium, potassium, chloride, bicarbonate, phosphate, magnesium) every 2-4 hours during initial treatment 2

Monitoring and Rate of Correction

• Target fluid replacement should correct estimated deficits within the first 24 hours 1, 2
• The induced change in serum osmolality should not exceed 3-8 mOsm/kg/h to minimize risk of cerebral edema and central pontine myelinolysis 1, 5
• Monitor vital signs, mental status, fluid input/output, and hemodynamic parameters hourly 2
• Check blood glucose every 1-2 hours until stable 2

Special Considerations

• In elderly patients or those with cardiac/renal compromise, use more cautious fluid rates with closer monitoring to prevent fluid overload 3, 2
• For severe hypernatremia with adequate hemodynamic stability, consider alternating 5% dextrose in water (D5W) with isotonic saline 3
• Fluid replacement alone will cause a fall in blood glucose level; withhold insulin until the blood glucose level is no longer falling with IV fluids alone (unless ketonaemic) 5, 4
• An initial rise in sodium level is expected and is not itself an indication for hypotonic fluids 5

Insulin Management in Relation to Fluid Therapy

• Once insulin is started, administer as continuous intravenous infusion at 0.1 U/kg/h (typically 5-10 units/hour) 2
• When plasma glucose reaches 300 mg/dl, decrease insulin infusion to 0.05-0.1 U/kg/h (3-6 U/h) 3, 2
• Target glucose level between 250-300 mg/dl until hyperosmolarity resolves 3, 2

Resolution Criteria

• Effective serum osmolality <300 mOsm/kg 4
• Hypovolemia corrected (urine output ≥0.5 ml/kg/h) 4
• Cognitive status returned to pre-morbid state 4
• Blood glucose <15 mmol/L (270 mg/dL) 4