Airflow perturbation device

A second, nonplethysmographic, technique for measuring airways resistance makes use of an airflow perturbation device (APD) (Fig. 21.18). In this approach, the patient breathes through a mouthpiece connected to a flow sensor. A pressure transducer measures the pressure at the mouth. At the outlet of the flow sensor is a rapidly rotating wheel that intermittently creates partial obstruction to airflow. During the time that there is no obstruction, the airflow is described by... 

Johnson, A. T., and C.-S. Lin, 1983A, Airflow Perturbation Device for Measuring Airway Resistance of Animals, Trans. ASAE, 26 503-506. 

Johnson, A. T., J. N. Hochheimer, and J. Windle, 1984, Airflow Perturbation Device for Respirator Research and Medical Screening, J. ISRP, 2 338-346. 

Lausted, C. G., and A. T. Johnson, 1999, Respiratory Resistance Measured by an Airflow Perturbation Device, Physiol. Meas., 20 21-35. 

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