Silverman, Nischom KThe stand-alone, USB-enabled Airflow Perturbation Device (APD) provides an average respiratory resistance (RR) measurement without connection to a computer and offers expanded functionality when connected to a computer. In both home and medical clinic settings, RR can provide a measure of impairment in obstructive respiratory disorders and the effectiveness of respiratory therapies. The APD measures RR during passive breathing by sensing the ratio of pressure increase to flow reduction during brief, partial airflow interruptions. Prior work has shown the APD to produce repeatable, sensitive RR measurements in humans and animals. The device of prior investigations incorporated a computer and data acquisition card. The research presented here demonstrates that the APD can provide accurate measurements in a stand-alone format and provide expanded function with a USB host computer.en-USThesisEngineering, Biomedical