J320 – A-a oxygen gradient requiring measurement of RQ by sampling mixed expired gas and using alveolar air equation
OHIP Cardio-Thoracic Surgery Code — PULMONARY FUNCTION STUDIES · Schedule of Benefits
A-a oxygen gradient is a diagnostic pulmonary function study that measures the difference between the alveolar concentration of oxygen and the arterial concentration of oxygen. The procedure requires the measurement of the respiratory quotient (RQ) by sampling mixed expired gas and using the alveolar air equation. This service is comprised of a technical component ('H' Fee) and a professional component ('P' Fee), which are billed for separately. The technical component is not payable outside a hospital setting. (Source: , ).
When to Use
- Use J320 when calculating the A-a gradient specifically via mixed expired gas sampling and the alveolar air equation, rather than relying on standard arterial blood gas (ABG) calculations alone.
- Select this code for complex pulmonary diagnostic workups where J319 (arterial blood gas) is insufficient to characterize gas exchange efficiency.
Common Pitfalls
- Billing the technical component (J320B) for tests performed in a private clinic or office setting, which is strictly prohibited by OHIP policy.
- Failing to submit the claim with the correct suffix (B for technical, C for professional), which will result in an automatic rejection.
- Attempting to bill J320 alongside J319 for the same patient encounter without clear clinical documentation justifying the necessity of both distinct procedures.
Billing Tips
- Ensure the professional component (J320C) is billed by the physician interpreting the data, while the technical component (J320B) is billed only by the facility where the gas sampling equipment is located.
Effective: April 1, 2025
H. Pulmonary Function Studies
PULMONARY FUNCTION STUDIES
Diagnostic
Pulmonary Function Studies, Diagnostic and Therapeutic Procedures
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