Lung Function Test Before and After an Inhaler

What it is

Spirometry measures airflow: how much air you can blow out and how fast it comes. You take the deepest breath you can and then empty your lungs into a tube as hard and as long as possible, and the machine records the volume against time. That alone shows whether air is leaving the lungs more slowly than expected. This code is the two-part version. After the first set of efforts, an inhaled bronchodilator is given, a waiting period passes while it takes effect, and the whole set of blows is repeated. Comparing the two runs is the actual test — it shows whether the airway narrowing loosens when the muscle around the breathing tubes is relaxed. A plain spirometry without that second round is a different, less expensive code.

Why it is done

• To investigate wheeze, cough, or breathlessness whose cause is not obvious
• To distinguish airway narrowing that responds to a bronchodilator from narrowing that does not
• To help sort out asthma from chronic obstructive lung disease, or to see how much of a mixed picture is reversible
• To judge how well current inhaled treatment is working
• To follow lung function over time in someone with a known lung condition

What to expect

You sit upright, a clip goes on your nose, and you seal your lips around a mouthpiece. The technician coaches loudly and insistently — "blow, blow, blow, keep going" — because the result depends entirely on maximum effort, and each manoeuvre is usually repeated several times until three consistent efforts are recorded. It can leave you lightheaded or coughing for a moment. Then the bronchodilator is given, typically through an inhaler with a spacer or a nebulizer, and after a wait of roughly fifteen minutes the blows are repeated. Allow around forty-five minutes for the appointment. Patients are often asked to hold certain inhaled medicines beforehand so the baseline is meaningful; the department sends those instructions in advance. A physician interprets the numbers and writes the report.

Questions worth asking

• Was the post-bronchodilator round actually performed? If only the first set of blows was done, the simpler spirometry code applies.
• Is the bronchodilator given during the test billed as a separate drug charge?
• Is there a separate interpretation fee from the physician reading the tracings, on top of the charge for the test itself?
• Is this being done in a hospital pulmonary function lab or in a pulmonologist's own office? The price gap between those two settings for this test is often large.
• If other lung measurements — lung volumes or gas transfer — are added on the same day, are they separate codes on the same bill?