Technical assessment of spirometers connected in series

Area of Science:

• Pulmonary Function Testing
• Medical Device Evaluation
• Respiratory Diagnostics

Background:

• Office spirometers are crucial for diagnosing obstructive lung diseases.
• Technical accuracy of spirometers is often assessed using simulated expiratory maneuvers.
• Comparing two spirometers in series is a method to evaluate office spirometer accuracy.

Purpose of the Study:

• To evaluate the accuracy of using two spirometers connected in series for office spirometry.
• To determine if the position of spirometers in a series affects measurement accuracy.

Main Methods:

• Two sets of spirometers (PocketSpiro with MicroLoop, PocketSpiro with SpiroScout) were connected in series.
• Standard American Thoracic Society curves were simulated under ambient temperature and pressure (ATP) and body temperature and pressure saturated (BTPS) conditions.
• Lung function indices (FVC, PEF, FEV1) were compared based on the PocketSpiro's upstream or downstream placement.

Main Results:

• Lung function indices were higher with the downstream spirometer in ATP conditions, with deviations up to 10%.
• In BTPS conditions, downstream spirometer placement led to underestimation compared to ATP.
• Observed discrepancies are attributed to altered flow characteristics and temperature drops.

Conclusions:

• Connecting spirometers in series produces variable results dependent on device placement.
• Measurements obtained from spirometers in series are not interchangeable.
• Individual spirometer calibration and testing are essential for reliable diagnostic accuracy.