Mixed DKA/HHS management

Diagnosis & Labs - The Hybrid Monster

• A metabolic storm combining severe hyperglycemia, ketoacidosis, and hyperosmolality.
• Core Lab Criteria:
  • Plasma Glucose: >600 mg/dL (often higher)
  • Arterial pH: <7.3
  • Serum Bicarbonate: <18 mEq/L
  • Serum Ketones: Positive
  • Effective Serum Osmolality: >320 mOsm/kg H₂O
• Calculate osmolality: $2 imes ext{Na} + ext{Glucose}/18$

⭐ The degree of acidosis may be less severe than in pure DKA, but the combination with extreme hyperosmolality signifies a graver prognosis.

IV Fluids & Potassium - Leaky Pipes & Live Wires

• Initial Fluid Resuscitation:

  • Start with 1-1.5 L of 0.9% Normal Saline (NS) over the first hour to restore intravascular volume.
  • If corrected serum Na⁺ is high or normal, switch to 0.45% NS.
  • When plasma glucose approaches 200-250 mg/dL, add dextrose to the IV fluid (e.g., D5-0.45% NS) to prevent iatrogenic hypoglycemia.

• Potassium Management:

  • ⚠️ Crucial: Check serum K⁺ before starting insulin.

⭐ Despite a normal or even high initial serum K⁺, patients have a significant total-body potassium deficit. Acidosis forces K⁺ out of cells, artificially inflating the serum measurement.

Insulin & Glucose Control - The Sugar Tamer

• IV Regular Insulin Infusion:
  • Start drip at 0.1 units/kg/hr.
  • Goal: ↓ Glucose by 50-75 mg/dL/hr.
• Glucose Management:
  • When blood glucose reaches ~200 mg/dL (DKA) or ~300 mg/dL (HHS):
    • Do NOT stop insulin.
    • Add dextrose to IV fluids (e.g., D5 ½ NS).
    • Reduce insulin infusion rate to 0.02-0.05 units/kg/hr.

⭐ Transition Protocol: Administer long-acting subcutaneous insulin 1-2 hours before stopping the IV insulin infusion to prevent rebound hyperglycemia and ketoacidosis.

Resolution & Transition - The Finish Line

• Resolution Criteria:

  • Anion gap closed (< 12 mEq/L)
  • Glucose < 200 mg/dL
  • Bicarbonate ≥ 15 mEq/L
  • Patient is alert and can eat.

• Transition to Subcutaneous (SQ) Insulin:

  • Administer basal (long-acting) insulin 1-2 hours before stopping the IV infusion.
  • Calculate total daily dose (0.5-0.8 U/kg/day); split 50% basal, 50% prandial (divided with meals).

⭐ Critical Step: Overlap SQ basal insulin with the IV insulin drip for 1-2 hours. Stopping the drip prematurely causes rebound hyperglycemia due to the short half-life of IV insulin.

High‑Yield Points - ⚡ Biggest Takeaways

• Mixed DKA/HHS features glucose >600 mg/dL alongside significant ketosis and acidosis.
• Aggressive fluid resuscitation with isotonic saline is the most critical initial step.
• Start IV insulin only after initial fluids and confirming potassium is >3.3 mEq/L.
• Bicarbonate therapy is rarely indicated, reserved only for severe acidosis with pH <6.9.
• The primary therapeutic goal is closing the anion gap, not simply normalizing blood glucose.
• Continuously monitor the anion gap, potassium, and serum osmolality.