A spirometer is designed to measure the rate and volume of airflow to and from the lungs during various phases of the respiratory cycle. The main purpose of these units involves accepting patient data, measuring patient ventilator efforts, and presenting diagnostic information. A hard copy must also be provided.

Manufacturers should clearly specify what parameters are evaluated by the spirometers, and whether it is volume or flow sensing. They should also indicate any computer interfacing capabilities along with the required software. The purchase price should factor in all necessary software costs. Manufacturers should also inform buyers on future spirometer improvements.