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M P Yeh

Publications and source records attributed to M P Yeh.

3 recordsLinked to original sources
PubMed1987

Turbine flowmeter vs. Fleisch pneumotachometer: a comparative study for exercise testing.

The purpose of this study was to investigate the characteristics of a newly developed turbine flowmeter (Alpha Technologies, model VMM-2) for use in an exercise testing system by comparing its measurement of expiratory flow (VE), O2 uptake (VO2), and CO2 output (VCO2) with the Fleisch pneumotachometer. An IBM PC/AT-based breath-by-breath system was developed, with turbine flowmeter and dual-Fleisch pneumotachometers connected in series. A normal subject was tested twice at rest, 100-W, and 175-W of exercise. Expired gas of 24-32 breaths was collected in a Douglas bag. VE was within 4% accuracy for both flowmeter systems. The Fleisch pneumotachometer system had 5% accuracy for VO2 and VCO2 at rest and exercise. The turbine flowmeter system had up to 20% error for VO2 and VCO2 at rest. Errors decreased as work load increased. Visual observations of the flow curves revealed the turbine signal always lagged the Fleisch signal at the beginning of inspiration or expiration. At the end of inspiration or expiration, the turbine signal continued after the Fleisch signal had returned to zero. The "lag-before-start" and "spin-after-stop" effects of the turbine flowmeter resulted in larger than acceptable error for the VO2 and VCO2 measurements at low flow rates.

Carbon Dioxide↗
PubMed1987

Measurement of anaerobic threshold in chronic airflow obstruction.

We compared determinations of anaerobic threshold (AT) made from measurements of arterial lactate concentration with AT determined from ventilatory response measurements of subjects with chronic airflow obstruction (CAO). Six untrained subjects with CAO performed incremental maximal cycle ergometer tests. Ventilation (VE); O2 uptake (VO2), CO2 output (VCO2); end-tidal CO2 fraction (FETCO2); and end-tidal O2 fraction (FETO2) were measured breath by breath. Arterial lactate concentration was sampled at rest and every 30 s during exercise from an indwelling arterial catheter. For three subjects with more severe airflow obstruction, plots of VE/VO2 and FETO2 failed to detect AT. In contrast, a systematic increase of the respiratory gas exchange ratio across the lung (R) accompanied increasing arterial lactate concentrations in all 6 subjects. We conclude that progressive increases of VE/VO2 and FETO2 cannot be relied upon for the measurement of AT in patients with severe CAO. Progressive increases of R unaccompanied by decreasing FETCO2 detect AT in CAO.

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