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A fast, digitally controlled flow proportional gas injection system for studies in lung function
J K K Kanhai1, P J Caspers, E G J Reinders
1Department of General Surgery, Erasmus Medical Centre Rotterdam, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands. jkkkanhai@hotmail.com
IEEE Transactions on Bio-Medical Engineering
|November 19, 2003
Summary
A new device precisely injects tracer gas into lungs of mechanically ventilated patients for lung volume studies. This flow-proportional injector ensures stable gas concentrations for accurate multiple breath indicator gas washout tests.
Area of Science:
- Respiratory Physiology
- Medical Device Engineering
Background:
- Accurate measurement of end-expiratory lung volume is crucial in respiratory diagnostics.
- Existing methods for tracer gas delivery may lack precision, especially in mechanically ventilated patients.
Purpose of the Study:
- To describe a novel device for flow-proportional injection of tracer gas into the lungs.
- To enable precise delivery of indicator gas for multiple breath indicator gas washout (MBGWO) technique.
- To facilitate studies on tracer gas uptake and elimination in respiratory physiology.
Main Methods:
- Development of a computer-controlled multivalve array system for precise gas injection.
- Utilized ten individual valves with varying diameters, controlled by input breathing signals.
- Employed sulphur hexafluoride (SF6) as the tracer gas, with a transmission rate of 80 Hz.
Main Results:
- The injector achieved a stable 1% SF6 concentration within 0.5 seconds.
- Demonstrated a full flow range of 0-10 L/min with a delay time of 70 ms.
- Showed increased flow output response above 3 Hz input frequency, with minor deviations in smaller valves.
Conclusions:
- The developed injector accurately delivers stable indicator gas concentrations (±0.005 L/min) for MBGWO tests.
- The device is suitable for use in human subjects and other respiratory physiology applications requiring indicator gas injection.
