A patient with type 1 diabetes presents in DKA with pH 7.10, PaCO2 18 mmHg, and HCO3 5 mEq/L. Using Winter's formula, is the respiratory compensation adequate?
- A Hypoventilation present; concurrent respiratory acidosis
- B Compensation adequate; no additional respiratory disorder ✓
- C Hyperventilation present; concurrent respiratory alkalosis
- D Cannot determine without the anion gap
Correct answer: B. Compensation adequate; no additional respiratory disorder
Explanation
Winter's formula predicts expected PaCO2 = (1.5 × HCO3) + 8 ± 2. With HCO3 of 5 mEq/L: expected PaCO2 = (1.5 × 5) + 8 = 7.5 + 8 = 15.5, range 13.5–17.5 mmHg. The measured PaCO2 of 18 mmHg is just at the upper limit (within 2 of 15.5), placing it within the expected range of adequate compensation. There is therefore no concurrent respiratory disorder.
Reference: Guyton & Hall, Textbook of Medical Physiology, 14th ed.
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