Abstract: An improved biological signal detector which is extremely sensitive, yet resistant to the effects of high frequency noise. A multiplexed signal representation of a plurality biological signals is demultiplexed by a detector circuit comprising a plurality of switches each of which controls an individual storage network. A switch logic control circuit synchronizes the various switches to close during the time intervals corresponding to the pulse amplitudes representing the particular signal of interest. The amplitude of the alternating component of each of the biological signals is stored in one of the respective storage networks over a number of pulse time intervals. In the preferred embodiment, the storage networks of the detector each have a time constant which is purposely chosen to be substantially longer than the time interval of the pulses.

Abstract: A method for monitoring a transducer array of individual pressure or force sensitive elements and for selecting the element within the array which most tracks the actual pulse waveform in an underlying artery, thus providing the most accurate measurement of the patient's blood pressure. The outputs of all of the transducer elements are employed in locating the particular element which is centrally located over the artery. A limited number of elements exhibiting local minima of diastolic pressure is first chosen. Then, pulse amplitude outputs from the limited number of transducer elements are employed in selecting that element within the limited-number group which is to be used for obtaining blood pressure measurements. The method provided by the present invention selects from the limited-number group of elements that element about which is centered the greatest spatially weighted average of a predetermined number of pulse amplitude values.

Abstract: A pulse wave detecting apparatus for detecting a blood pressure pulse wave of an arterial vessel of a subject, based on an oscillatory motion of at least one contact element which is adapted to be depressed against a surface of a body member of the subject, such that each contact element is iscillated in response to the pulsation of the arterial vessel. The apparatus includes a main frame for supporting each contact element such that the contact element is movable relative to the main frame fixed in position on the surface of the body member. A positioning device is provided, which is capable of at least moving the contact element relative to and along the body surface, in a direction perpendicular to the arterial vessel, to thereby locate one of the at least one contact element right above the arterial vessel. A pressing device is provided for moving each contact element relative to the main frame, in a direction toward the surface, for forcing each contact element against the surface.

Abstract: An interference resistant biomedical transducer for monitoring the acoustic output of a patient's cardiac or respiratory system which provides a high degree of rejection of acoustic noise and spurious electromagnetic signals. The transducer comprises a piezoelectric diaphragm assembly having electrodes which produce a differential output signal. The transducer housing includes a massive metal disc and a compliant handle which provide a mechanical filter to remove undesired signals such as those related to motion of the patient and ambient acoustic noise.

Abstract: A method and apparatus for ensuring accurate measurement of blood pressure regardless of the position of the sensing transducer relative to the position of the patient's heart. The method and apparatus provides a hydrostatic balancing system in which a column of fluid is used to offset the hydrostatic pressure created by the corresponding column of blood contained in the blood vessel in the limb upon which the measurement is being taken. A flexible tube is routed along the patient's limb with one end being positioned at heart level and the other end terminating at the occlusion cuff which supports the pressure sensing transducer. The tube is filled with fluid and is connected to a fluid reservoir chamber located at approximately the same level as the patient's heart. The hydrostatic pressure created by the fluid in the tube effectively balances the corresponding hydrostatic pressure created by the blood in the blood vessel.