A 28-year-old man with known type 1 diabetes mellitus presents to the emergency department with a 2-day history of polyuria, polydipsia, and progressive lethargy. He had missed his insulin injections for 3 days due to financial constraints. On examination, he is drowsy, respiratory rate 28/min with deep laboured breathing, blood pressure 110/70 mmHg, and heart rate 110/min. His breath has a fruity odour. Laboratory investigations reveal: blood glucose 580 mg/dL, arterial pH 7.18, HCO₃⁻ 10 mEq/L, anion gap 18, serum sodium 128 mEq/L, serum potassium 6.2 mEq/L, and serum creatinine 1.8 mg/dL. Urine dipstick shows 4+ ketones and 2+ protein. What is the most appropriate immediate management after securing airway and establishing IV access?

Explanation

## Diagnosis: Diabetic Ketoacidosis (DKA) **Key Point:** This patient meets diagnostic criteria for DKA: hyperglycaemia (580 mg/dL), metabolic acidosis (pH 7.18, HCO₃⁻ 10), elevated anion gap (18), and ketonuria with Kussmaul breathing (fruity breath). ## Management Priorities in DKA **High-Yield:** The sequence of DKA management is: (1) Airway/IV access, (2) Fluid resuscitation with 0.9% saline, (3) Insulin therapy, (4) Electrolyte monitoring and replacement. ### Fluid Resuscitation - **0.9% normal saline** is the initial fluid of choice (not hypotonic solutions) - Typical deficit: 5–10 L; replace 50% in first 12 hours - Hypotonic fluids (0.45% saline) risk cerebral oedema and are avoided in acute DKA ### Insulin Therapy - **Bolus:** 0.1 unit/kg IV (e.g., 7 units for a 70 kg patient) - **Infusion:** 0.1 unit/kg/hr continuous IV infusion - Insulin **must not be withheld** despite hyperkalaemia; it drives K⁺ intracellularly - Insulin and fluids are given **concurrently**, not sequentially ### Potassium Management - **Do NOT give potassium before insulin** — insulin will shift K⁺ into cells and risk fatal hypokalaemia - Serum K⁺ 6.2 mEq/L appears elevated but is **pseudohyperkalaemia** (due to acidosis and dehydration) - Once insulin is started, K⁺ will drop; monitor and replace as needed - Typical replacement: 20–40 mEq/L once urine output is confirmed ### Bicarbonate Therapy - **NOT indicated** in DKA unless pH < 6.9 (this patient's pH is 7.18) - Bicarbonate delays ketone clearance and risks hypokalaemia ```mermaid flowchart TD A[DKA Diagnosis Confirmed]:::outcome --> B[Secure airway & IV access]:::action B --> C[Start 0.9% saline bolus]:::action C --> D[Insulin 0.1 unit/kg IV bolus]:::action D --> E[Insulin 0.1 unit/kg/hr infusion]:::action E --> F[Monitor K+ closely]:::decision F -->|K+ drops below 5.5| G[Add K+ to fluids 20-40 mEq/L]:::action F -->|K+ remains elevated| H[Continue insulin & fluids]:::action G --> I[Repeat labs q2-4h]:::action H --> I ``` **Clinical Pearl:** The combination of insulin + fluid resuscitation corrects both hyperglycaemia and acidosis. Insulin lowers glucose by suppressing lipolysis (stopping ketone production) and enhances cellular glucose uptake. Fluids dilute glucose and restore renal perfusion, allowing glucosuria. **Mnemonic: DKA Management = "FIK"** — **F**luids (0.9% saline), **I**nsulin (0.1 unit/kg bolus + infusion), **K**+ monitoring (replace only after insulin started). [cite:Harrison 21e Ch 396]