A DKA Patient

 Study Notes: DKA Lecture – Dr. Sarah Kraiger

Introduction

• Topic: Sick diabetic ketoacidosis (DKA) patients.

• Focus: Not protocol memorization, but pathophysiology-driven management.

1. Conceptual Framework

• DKA is not about the sugar.

  • Goal: Prevent glucose from dropping too low, too fast.

  • The real problem: ketoacidosis.

• Pathophysiology: Think of DKA as an insulin supply–demand mismatch.

  • Supply problem: Not enough insulin (missed doses, lack of access, pancreatic failure).

  • Demand problem: Physiologic stress increases insulin needs (sepsis, MI, shock).

• Stress hormones (cortisol, epinephrine):

  • Directly activate lipase → release of free fatty acids → ketosis.

  • Induce tissue insulin resistance → worsen intracellular glucose deficit.

• Type 2 diabetics (esp. young/healthy): Can still get DKA due to strong stress responses.

• Elderly patients: Blunted stress response → more likely HHS, not DKA.

2. Diagnosis

• Not always straightforward.

• Pitfall #1: High glucose + acidosis ≠ always DKA.
  Example: elderly patient with mesenteric ischemia → lactic acidosis + hyperglycemia (not DKA).

• Pitfall #2: Normal glucose/bicarb ≠ exclude DKA.
  Example: vomiting patient with pancreatitis + diabetes → normal bicarb/pH due to mixed metabolic alkalosis and acidosis.

  • Always calculate anion gap.

  • Anion gap ↑ = suspect DKA, even if labs “look normal.”

• Lesson: Don’t anchor on glucose/bicarb alone.

3. DKA as a Red Herring

• Danger: Focusing only on DKA → miss underlying physiologic stressor.

• Must actively search for causes: infection, ischemia, shock, intoxication, etc.

• Chicken-or-egg problem:

  • DKA can cause altered mental status.

  • But altered mental status from another cause (stroke, sepsis) may trigger stress → DKA.

4. Sick vs. Not Sick

• Use the eyeball test + physiologic “cliff” concept.

  • Where is the patient relative to decompensation?

• ABGs: Not for diagnosis, but for severity.

  • Use to assess compensation:

    • Shortcut: Is CO₂ ≈ last 2 digits of pH?
      → If yes = appropriate compensation.

  • pH < 7.10 → at the edge of the cliff (max compensation reached).

  • Superimposed resp. acidosis = very high risk of rapid decompensation.

5. Airway Management

• Avoid intubation if possible.

  • Spontaneous ventilation achieves higher minute ventilation than a ventilator.

  • Paralysis/apnea → precipitous pH drop → cardiac arrest.

• Alternative:

  • Use BiPAP early if CO₂ rising or WOB high.

  • High-flow nasal cannula if vomiting risk.

• If forced to intubate: extreme caution, minimize apnea time.

6. Management Principles

• Protocols: Helpful for not-sick patients, but manual management often better for sick ones.

• Potassium:

  • Biggest pitfall: under-replacement.

  • Use central line if needed → allow high infusion rates (20–30 mEq/hr).

  • Use antiemetics early to allow oral K⁺.

  • Don’t forget magnesium (low Mg prevents K repletion).

• Bicarbonate:

  • Goal = fix acidosis (with insulin), not transiently fix acidemia.

  • Bicarb lowers K⁺ → limits insulin use.

  • Only consider:

    • If forced to intubate a severely acidemic patient (temporary bridge).

    • Later phase: non-gap hyperchloremic acidosis after large-volume fluids & ketoaciduria → then bicarb may help prevent relapse into DKA.

• Fluids:

  • Correct intravascular volume deficit.

  • Avoid 10 L normal saline → worsens acidosis (hyperchloremic).

  • Prefer LR (Lactated Ringer’s).

  • Monitor for cerebral edema and volume overload.

  • Separate fluid quantity from fluid composition.

7. Key Takeaways

• DKA = insulin supply-demand mismatch, not just hyperglycemia.

• Always calculate the anion gap; don’t be fooled by normal glucose or bicarb.

• Look for the underlying physiologic stressor.

• Avoid intubation; support spontaneous ventilation whenever possible.

• Be aggressive with potassium repletion (and Mg).

• Use bicarb sparingly—not for routine management.

• Fluids: resuscitate smartly, avoid chloride overload.

• Protocols are safe for stable patients, but sick DKA requires active thinking.