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Spirometry is one of the ongoing pulmonary function tests (PFTs) we use to monitor lung function following transplantation. As you know, vigilance is a key to success in lung transplant patients, and spirometry is one of the simplest and best tools we have to catch even small changes in lung function.

Spirometry is routinely performed at each of your clinic visits, but you will need to also measure your lung function at home every day. You will receive your own personal portable microspirometer, and instructions how to use it, before leaving the hospital.

The maneuver

To perform a spirometric maneuver, take in as deep a breath as possible and then blow out as hard and as long as possible through your mouth into the microspirometer. You must maintain a tight seal between your mouth and the mouthpiece. We also recommend you wear a nose clip for best results. The goal is for every molecule of your exhaled breath to be captured by the microspirometer.

The home spirometer records two numbers. Forced vital capacity (FVC) represents the total volume of air blown out. Forced expired volume in 1 second (FEV1) represents the amount of air blown out in the first one second of exhaling.

Perform 3 maneuvers at the same time each day and record the highest FVC and FEV1 readings you obtain, even if they come from different maneuvers. Note that the readings obtained at home may run a little lower than those recorded in the PFT lab.

Call the Lung Transplant Center if you experience a drop of 10% in either of the numbers over 2 days time. Depending on your situation, you may be asked to come to the PFT laboratory for further testing.