A 28-year-old man with type 1 diabetes mellitus presents to the emergency department with a 2-day history of polyuria, polydipsia, and vomiting. On examination, he is tachypneic (RR 28/min), blood pressure is 110/70 mmHg, and there is a fruity odor on his breath. Laboratory investigations show: pH 7.25, HCO₃⁻ 12 mEq/L, glucose 450 mg/dL, β-hydroxybutyrate elevated, and anion gap 16. Serum potassium is 5.8 mEq/L. What is the most appropriate immediate next step in management?

Explanation

## Management of DKA: Immediate Priorities **Key Point:** The cornerstone of DKA management is simultaneous fluid resuscitation and insulin therapy, with careful potassium monitoring. Despite elevated serum K⁺, total body potassium is depleted due to osmotic diuresis and acidosis-induced shift. ### Why Fluid Resuscitation Comes First **High-Yield:** In DKA, insulin should NOT be started until: 1. IV access is established 2. Initial fluid resuscitation has begun (0.9% NS bolus) 3. Potassium is known and being monitored Reasoning: Insulin drives K⁺ intracellularly, and starting it in a hypokalemic patient (total body deficit) without fluid support risks severe hypokalemia and arrhythmias. The serum K⁺ of 5.8 is deceptively high — it reflects acidosis-driven shift, not total body stores. ### DKA Management Algorithm ```mermaid flowchart TD A[DKA Diagnosis Confirmed]:::outcome --> B[Establish IV Access]:::action B --> C[0.9% NS Bolus<br/>1-1.5 L over 1 hour]:::action C --> D{Serum K+ known?}:::decision D -->|K+ < 3.5| E[Add KCl to IV fluids<br/>BEFORE insulin]:::urgent D -->|K+ 3.5-5.5| F[Start insulin infusion<br/>0.1 units/kg/hr]:::action D -->|K+ > 5.5| G[Monitor K+ closely<br/>Start insulin after<br/>initial fluid bolus]:::action E --> H[Continuous monitoring<br/>K+, glucose, pH]:::action F --> H G --> H ``` ### Potassium Management in DKA | Serum K⁺ Level | Action | |---|---| | < 3.5 mEq/L | Add 40 mEq KCl per liter of IV fluid; delay insulin | | 3.5–5.5 mEq/L | Add 20 mEq KCl per liter; start insulin | | > 5.5 mEq/L | Do NOT add K⁺; monitor closely; start insulin cautiously | **Clinical Pearl:** The patient's K⁺ of 5.8 is high, but this is pseudohyperkalemia from acidosis. Once insulin and fluids are given, K⁺ will drop rapidly. Monitoring every 2–4 hours is essential. ### Why NOT Sodium Bicarbonate? **Warning:** Bicarbonate is NOT routinely used in DKA unless pH < 6.9 (rare) because: - Insulin and fluids correct acidosis naturally - Bicarbonate worsens hypokalemia and cerebral edema risk - It does not address the underlying ketosis [cite:Harrison 21e Ch 396]