Definition: Spirometry is a breathing test that measures how much air you blow out and how quickly. MedlinePlus says you breathe into a mouthpiece connected to a spirometer, which records the amount and rate of air over time. FEV1, the air forced out in the first second, is one of its main numbers.
MedlinePlus says some measurements use normal breathing and others a forced breath out after a deep breath in. Results are compared with predicted values for people of the same age, sex, height and weight, and given as a percentage. Results well below predicted may point to lung disease. The test can cause brief shortness of breath, lightheadedness or coughing.
The Afrezza label requires spirometry with FEV1 before starting inhaled insulin, as part of its boxed warning.
| When | What the label says |
|---|---|
| Before starting | Medical history, physical exam and spirometry (FEV1) |
| After the first 6 months | Spirometry, even without symptoms |
| Every year after that | Spirometry, even without symptoms |
| FEV1 down 20% or more from baseline | Consider stopping Afrezza |
Over up to 2 years, adults on Afrezza had a 40 mL greater fall in FEV1 than on comparators, starting in the first 3 months. In people with asthma, FEV1 fell by a mean of 400 mL 15 minutes after a single dose.
A dated note of each spirometry result next to your dose history makes it easy to compare later results with the starting value, which is what the label's 20% rule is measured against.
Read more on Dose Track: Who can use inhaled insulin · Afrezza side effects