Physiology

Case presentation  A 67 year-old man with COPD is somnolent with shallow breathing. ABG: pH 7.25, PaCO₂ 60 mmHg, HCO₃⁻ 26 mEq/L. Arrow method For each ABG variable, imagine an arrow showing its direction from normal. pH 7.35-7.45: < 7.35 → ↓, > 7.45 → ↑. PaCO₂ 35-45 mmHg:  > 45 → ↑, < 35 → ↓. HCO₃⁻ 22-26 […]