What is a spirometer?

A spirometer is used to make the most common of pulmonary function tests (PFTs). It is a respiratory flowmeter that determines how well the lungs are working by measuring the amount of inhaled air, amount of exhaled air and how quickly it is exhaled. Used to diagnose asthma, chronic obstructive pulmonary disease (COPD) and other respiratory conditions, there are several terms defined in dynamic spirometer measurements. Three of the most common terms that are also used to rate commercially available spirometers are:

• Forced vital capacity (FVC) – the largest amount of air that can be forcefully exhaled after breathing in as deeply as possible
• Forced expiratory volume (FEV) – how much air is forced from the lungs in one second and
• Peak expiratory flow (PEF) – the highest forced expiratory flow measured with a peak flow meter

Depending on the application requirements, from hospital to home consumer use, spirometer measurements are made using a variety of flow measurement techniques including:

• Counting/paddle wheel
• Pressure sensor (to calculate flow)
• Stator/rotor

A consumer-oriented spirometer, such as the Vitalograph asma-1, measures PEF and FEV1 and  the readings may be integrated with smart phone or tablet for ePRO data collection. It uses the stator/rotor mass flow meter principle, has a flow / volume range (PEF) of 25 to 840 L/min BTPS (body temperature, ambient pressure, saturated with water vapor) and FEV1 from 0 to 9.99 L BTPS.Vitalograph Asma-1 Electronic Asthma Monitor. Image courtesy of Medical Device Depot.

After surgery, a potentially disposable mechanical incentive spirometer is used by patients to keep their lungs clear and help keep their lungs active during the recovery process.

Incentive Spirometer. Image courtesy of Cleveland Clinic.