Home
Back
A-a Gradient Equation:
| From: | To: |
The Alveolar-arterial (A-a) gradient measures the difference between alveolar oxygen partial pressure (PAO₂) and arterial oxygen partial pressure (PaO₂). It helps assess the efficiency of oxygen transfer from alveoli to blood in canine patients.
The calculator uses the A-a Gradient equation:
Where:
Explanation: The A-a gradient reflects the efficiency of pulmonary gas exchange. A normal gradient indicates efficient oxygen transfer, while an increased gradient suggests ventilation-perfusion mismatch or diffusion impairment.
Details: A-a gradient assessment is crucial for diagnosing respiratory disorders in dogs, including pneumonia, pulmonary edema, pulmonary embolism, and assessing oxygenation efficiency in critical care patients.
Tips: Enter both PAO₂ and PaO₂ values in mmHg. Ensure measurements are taken under consistent conditions (room air or specified FiO₂). Values must be positive numbers.
Q1: What is the normal A-a gradient range in dogs?
A: Normal A-a gradient in dogs is typically 5-15 mmHg on room air, but can vary with age and breed.
Q2: When is A-a gradient increased in dogs?
A: Increased A-a gradient occurs in conditions like pneumonia, pulmonary edema, ARDS, pulmonary fibrosis, and pulmonary thromboembolism.
Q3: How does FiO₂ affect A-a gradient?
A: A-a gradient normally increases with higher FiO₂. Interpretation should consider the inspired oxygen concentration.
Q4: What are limitations of A-a gradient?
A: Affected by altitude, barometric pressure, and requires accurate blood gas analysis. Not a standalone diagnostic tool.
Q5: How is this different from human A-a gradient?
A: While the calculation is identical, normal values and clinical interpretation may differ between species due to anatomical and physiological variations.