Diabetic Ketoacidosis (DKA): Pathophysiology, Diagnosis, and Management

Diabetic ketoacidosis (DKA) is a life-threatening endocrine emergency most often seen in Type 1 diabetes. This guide covers the pathophysiology, triggers, diagnostic criteria, and the stepwise FIKAP management approach, with a focus on nursing priorities and high-yield exam points.

What Is DKA?

• A life-threatening complication caused by absolute insulin deficiency, typically in Type 1 diabetes.
• Without insulin, glucose cannot enter cells for energy.
• The body breaks down fat for fuel, producing ketones, which cause metabolic acidosis.

Precipitating Factors (The "I's" Mnemonic)

• Infection — the most common trigger overall
• Insulin omission — the most common cause in known diabetics
• Infarction — MI or stroke
• Injury — trauma, surgery
• Immune — new Type 1 diagnosis
• Iatrogenic — steroids, diuretics, antipsychotics

Clinical Presentation

• Kussmaul respirations: deep, rapid breathing to blow off CO₂
• Fruity (acetone) breath odor — specific to DKA
• Abdominal pain that mimics an acute abdomen but resolves with treatment
• Polyuria, polydipsia, dehydration, tachycardia, and hypotension

Diagnostic Criteria

• Anion gap = Na − (Cl + HCO₃)
• Initial serum potassium may appear normal or high, but total body potassium is low.

Management — FIKAP Mnemonic

Treatment Details

Fluids

• Begin with 0.9% normal saline at 15–20 mL/kg/hr.
• Give the first 1–2 liters rapidly to restore volume.
• After volume repletion, switch to 0.45% normal saline.
• Add dextrose 5% when blood glucose falls below 250 mg/dL.

Insulin

• Give regular insulin as a continuous IV infusion via pump.
• Do not give IV push insulin.
• Do not stop insulin when glucose normalizes — continue until ketones clear.
• Transition to subcutaneous insulin once the anion gap closes and the patient can eat.
• Overlap subcutaneous insulin with IV insulin by 1–2 hours to prevent rebound hyperglycemia.

Potassium

• Do not give insulin if K⁺ is below 3.3 mEq/L.
• Once K⁺ drops below 5.0, add 20–30 mEq potassium to each liter of IV fluid.
• Monitor potassium every 2–4 hours.
• Never give IV push potassium; always dilute and infuse slowly.

Bicarbonate

• Rarely used — can cause hypokalemia and cerebral edema.
• Only indicated for severe acidosis (pH < 6.9).

Phosphorus

• Replace if severe hypophosphatemia develops.
• Hypophosphatemia can cause cardiac and respiratory muscle weakness.

Priority Actions (Exam Focus)

• First action: initiate IV fluids immediately, before insulin.
• Before starting insulin, ensure K⁺ is above 3.3 mEq/L.
• Most concerning finding during treatment: new headache and confusion — suggests cerebral edema.

Indications of Improvement

• Anion gap closes to below 12
• Bicarbonate rises above 18 mEq/L
• Blood glucose falls to 200–250 mg/dL
• Ketones clear and mental status improves

Complications

DKA vs HHS

Nursing Priorities

• Do not give insulin if potassium is below 3.3 mEq/L.
• Never stop insulin until ketones clear.
• Position unconscious patients on their side to prevent aspiration.
• Identify and treat the underlying cause (e.g., infection, missed insulin).

Key takeaways

• DKA results from absolute insulin deficiency in Type 1 diabetes, causing hyperglycemia, ketones, and metabolic acidosis.
• Diagnostic triad: glucose > 250, pH < 7.30, bicarbonate < 18, with anion gap > 12 and ketones present.
• Management follows FIKAP: Fluids first, Insulin (hold if K⁺ < 3.3), Potassium replacement, Acid–base monitoring, Phosphorus if needed.
• IV fluids come before insulin; potassium must be ≥ 3.3 mEq/L before starting insulin.
• The most feared treatment complication is cerebral edema — watch for new headache and confusion, especially in children.
• Add dextrose to IV fluids when glucose reaches 250 mg/dL, and continue insulin until ketones clear and the anion gap closes.