
A–a Gradient Explained: Alveolar-Arterial Oxygen Difference
Learn how to calculate and interpret the A–a gradient, what is normal, and how it helps identify causes of hypoxemia like V/Q mismatch, shunt, and diffusion impairment.
Evidence-based posts for clinicians and students covering ABG and VBG interpretation, breathwork, COPD, oxygenation, ventilation, and respiratory education.
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Learn how to calculate and interpret the A–a gradient, what is normal, and how it helps identify causes of hypoxemia like V/Q mismatch, shunt, and diffusion impairment.

Learn how to distinguish respiratory vs metabolic acidosis using pH, PaCO₂, and HCO₃⁻, with causes, compensation patterns, and clinical examples.

Clinical scenarios, correlation caveats, and practical guidance for sampling strategy.