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Objective.The aim of this study was to compare clinicallyrelevant performance of: 1) a prototype respiratory sensor based oncapnometry with two alternative signal receptor fixations, 2) afiberoptic humidity sensor and 3) human visual observation. Comparativeprovocation tests were performed on volunteers at the Post-AnesthesiaCare Unit at Västerås Central(More)
Respiratory failure can be difficult to predict. It can develop into a life-threatening condition in just a few minutes, or it can build up more slowly. Thus continuous monitoring of respiratory activity should be mandatory in clinical, high-risk situations, and appropriate monitoring equipment could be life-saving. The review considers non-invasive methods(More)
The need for continuous, noninvasive, and reliable respiratory rate monitoring during recovery from general anesthesia has long been recognized. Alternative principles can be grouped into those detecting the respiratory effort, and those detecting the actual result, i.e. the respiratory gas flow. The second category is of greatest interest for patient(More)
To study the degree of stenosis from the acoustic signal generated by the turbulent flow in a stenotic vessel, so-called phonoangiography was first suggested over 20 years ago. A reason for the limited use of the technique today may be that, in the early work, the theory of how to relate the spectrum of the acoustic signal to the degree of the stenosis was(More)
Acoustic sensors based on the well-known relation between sound velocity and mean molecular mass are suggested for the determination of small concentrations of `̀ pollutants'', such as CO2, in air. The theoretical basis for high resolution is outlined, and a basic design is presented, together with experimental results. Sound velocity is measured(More)
The present techniques for breath alcohol determination have usability limitations concerning practical use and the time and effort required for the test person. The rationale of the physiological assumptions in a recently demonstrated technique for breath analysis without a mouthpiece is investigated in this paper. Expirograms quantifying ethanol, carbon(More)
A system for patient monitoring during magnetic resonance imaging (MRI) is described. The system is based on remote auscultation of heart sounds and respiratory sounds using specially developed pickup heads that are positioned on the precordium or at the nostrils and connected to microphones via polymer tubing. The microphones operate in a differential mode(More)
STUDY OBJECTIVES To determine the frequency of true and false alarms and to determine the frequency of alarm failures for various parameters when using a postanesthesia monitoring system. DESIGN Open prospective study. SETTING Postanesthesia care unit at a university hospital. PATIENTS 123 ASA physical status I-IV patients who underwent general or(More)
End tidal carbon dioxide measurements with an electro acoustic capnograph prototype have been demonstrated. The aim of this study was to verify that it is possible to obtain an adequate capnogram using the prototype and to investigate the influence of ambient temperature and humidity variations. By simultaneous measurements with a reference capnograph, on(More)