Journal ArticleDOI
Ultrasonic Measurement of Respiratory Flow
David I. Plaut,John G. Webster +1 more
TLDR
This work reviews ultrasonic measurement of fluid flow with emphasis on ultrasonic pneumotachometers (UPTM's) and UPTM's, and presents four principle types: time of flight, sing around, phase shift, and phase-locked frequency shift.Abstract:
We review ultrasonic measurement of fluid flow with emphasis on ultrasonic pneumotachometers (UPTM's). For PTM's we discuss specifications such as dynamic range, resistance, and frequency response. We review fluid flow principles and point out the problems of nonultrasonic PTM's For UPTM's we describe transducer construction, attenuation versus frequency, reflection at interfaces, and acoustic field patterns. We present four principle types: 1) time of flight, 2) sing around, 3) phase shift, and 4) phase-locked frequency shift. For each, we detail principles, advantages, disadvantages, and potential for future development.read more
Citations
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Journal ArticleDOI
Flow measurement in mechanical ventilation: A review
TL;DR: The most promising emerging approaches for flowmeters design (i.e., fiber optic technology and three dimensional micro-fabrication) are briefly reviewed showing their potential for this application.
Journal ArticleDOI
A novel sensor for routine continuous spirometry of intubated patients.
TL;DR: The D-lite sensor, in a single, lightweight adaptor piece, encloses flow, airway pressure, and sidestream gas measurement, which can be handled by sophisticated computer algorithms at the host-monitor end.
Journal ArticleDOI
Variable ratio threshold and zero-crossing detection based signal processing method for ultrasonic gas flow meter
TL;DR: In this article, a variable ratio threshold and zero-crossing detection based digital signal processing method is proposed for ultrasonic gas flow meter, where the ultrasonic echo signal is normalized, and the ratio value is used as the threshold value to determine the feature point.
Journal ArticleDOI
Design and Construction of a Pulsed Ultrasonic Air Flowmeter
TL;DR: This respiratory air flowmeter is extremely fast and accurate, with low noise (below 9ml/s), with a wide flow range (bidirectional from 0 to 9 l/s and with a linear frequency response up to 70 Hz).
Journal ArticleDOI
Sensitivity of Breath-to-Breath Gas Exchange Measurements to Expiratory Flow Errors
TL;DR: It is concluded that an error sensitivity of less than one is achieved by a method that incorporates measurements of nitrogen flow into and out of the lung, and includes the analysis of breath-to-breath changes in lung volume.
References
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Book ChapterDOI
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TL;DR: In this article, it was shown that for a wide class of conservative systems in fluid dymamics changes in amplitude along the rays may be computed from conservation of wave action, defined as the wave energy divided by the intrinsic frequency.
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TL;DR: In this paper, the wave equations for the propagation of sound in an inhomogeneous and moving medium are established and a generalization of Kirchhoff's theorem (Huygens' principle) is given for a moving medium.
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