Pulmonology Coding Alert

Question: What is the CPT for lung volumes by nitrogen wash out? Tell me more about how it is used and based on what diagnosis.New Jersey SubscriberAnswer: The code for the nitrogen washout is 94240 (Functional residual capacity or residual volume: helium method, nitrogen open circuit method, or other method).How: The patient breathes oxygen for 7 minutes, having been turned into the system at functional residual capacity (FRC). All the expired gas is collected from the patient and analyzed for nitrogen (N2). The nurse/medical staff measures the inspired N2, expired N2, and expired patient volume. He also determines the FRC. By substracting the expired reserve volume -- patient blows out all the air from the end expiratory position to residual volume -- the residual volume (RV) is determined. It is the only lung volume of 4 which cannot be measured directly.Another test similar to the N2 washout is helium dilution method, wherein [...]