Noninvasive System for Assessing Cardiac Filling Pressure
Abstract (Set) The invention is a system for assessing cardiac filling pressure noninvasively. It consists of a device and method that can be used at the bedside, in clinic, in the emergency department, an intensive care unit, or at home. It can be used repeatedly and conveniently, and is inexpensive to operate. Description (Set) The invention consists of a photoplethysmography (PPG) transducer and a pressure transducer that are connected to a central processor. The clinician places the PPG transducer on the patient's finger and the pressure transducer into the patients mouth, separated by tubing and/or mouthpiece. The patient blows into the tube, through which the device measures the expiratory pressure. Pulse pressure of the photoplethysmography waveform, which is the width of the signal from minimum to maximum during one cardiac cycle, is measured. The device compares the pulse pressure near the end of the expiratory effort to the pulse pressure at baseline before the expiratory effort begins. The ratio of the pulse pressure near the end of the expiratory effort to the pulse pressure before the beginning of the expiratory effort is used. This is called the pulse amplitude ratio. The device displays the photoplethysmography waveform, the expiratory effort waveform and level, and the pulse amplitude ratio number after the expiratory effort has ceased. The pulse amplitude ratio determines whether the patient has normal filling pressure, very elevated filling pressure, or whether the measurement is in a middle range that does not reliably indicate by itself a specific filling pressure. Proposed Use (Set) A product can be produced which a clinician uses to assess filling pressure in a variety of settings, including but not limited to: 1) An outpatient clinic, 2) An emergency department, 3) A medicine ward, 4) An intensive care unit, 5) At home. The product could be free-standing, could be on a rolling cart, could be portable, or could fit in a coat pocket. The expiratory pressure could be come constant value such as 20 mmHg or could be some predetermined pattern. The duration of expiration could be 10 seconds or any other time desired. The display of the device could be a number, a waveform, words, or any combination thereof. The device could also have a miniature printer attached, or could have a connector that allows its data to be uploaded to a printer or computer.
Silber, Harry A.
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