Method to produce American Thoracic Society flow-time waveforms using a mechanical pump

Area of Science:

• Pulmonary Function Testing
• Biomedical Engineering
• Respiratory Device Calibration

Background:

• The American Thoracic Society (ATS) introduced 26 new standard flow-time waveforms for device testing.
• Higher frequency content in these waveforms can cause gas compression losses in mechanical pumps.
• These losses lead to reduced pump flow output, impacting device accuracy.

Purpose of the Study:

• To investigate the impact of gas compression on mechanical pump output for ATS waveform testing.
• To evaluate the accuracy of different methods for measuring pump flow.
• To develop a method for generating ATS waveforms accurately despite compression losses.

Main Methods:

• A mechanical pump was used to generate flows for testing mini-Wright and Assess peak expiratory flow (PEF) meters.
• Pump output flow was measured using a pneumotachometer and a validated piston displacement/pressure method.
• New input waveforms were derived to compensate for gas compression losses.

Main Results:

• The piston displacement/pressure method accurately measured pump output with lower resistance and dead space.
• Pump output flow was significantly lower than desired for both mini-Wright (7.1%) and Assess (10.9%) meters with waveform No. 26.
• The developed input waveform method successfully produced all 26 ATS flow-time waveforms accurately.

Conclusions:

• Gas compression is a significant factor affecting mechanical pump accuracy when generating high-frequency ATS waveforms.
• A novel input waveform generation method effectively overcomes compression losses.
• This approach ensures reliable and accurate testing of respiratory diagnostic and monitoring devices using the latest ATS standards.