Abstract: The system provides information to facilitate efficient optimization of programmer settings for cardiac pacemakers. It simultaneously measures a patient's electrocardiogram and peripheral blood pressure (or volumetric displacement) waveform in order to calculate, in real-time and non-invasively, a value correlated to the pre-ejection time (PET) and, optionally, ejection duration (ED) for the patient's left ventricle. The peripheral pulse waveform can be monitored with a wrist mounted tonometer, or a suitable brachial cuff device. The time difference between the occurrence of the R-wave on the ECG trace and the foot of the pulse on the radial blood pressure waveform is defined as a surrogate pre-ejection time interval (SPET).

Abstract: The system provides information to facilitate efficient optimization of programmer settings for cardiac pacemakers. It simultaneously measures a patient's electrocardiogram and peripheral blood pressure (or volumetric displacement) waveform in order to calculate, in real-time and non-invasively, a value correlated to the pre-ejection time (PET) and, optionally, ejection duration (ED) for the patient's left ventricle. The peripheral pulse waveform can be monitored with a wrist mounted tonometer, or a suitable brachial cuff device. The time difference between the occurrence of the R-wave on the ECG trace and the foot of the pulse on the radial blood pressure waveform is defined as a surrogate pre-ejection time interval (SPET).

Abstract: A high frequency oscillatory ventilator for infants and adults using feedback control to maintain either the desired tidal volume or pressure delivered to the subject. The inspiratory to expiratory time ratio of the ventilator is variable. The ventilator corrects the measured pressure for arbitrarily-sized endotracheal tubes and calculates the actual pressure or tidal volume delivered to the subject. The ventilator also separates the source of the tidal volume oscillations from the patient circuit with a flexible membrane or diaphragm, allowing transmission of oscillating tidal volumes while blocking mean airway pressures. The patient circuit is flexible, but fabricated from low-compliance material to minimize the loss of tidal volume. The ventilator uses feedback control of the exhaust flow to maintain mean airway pressure in the presence of an independently controlled bias flow.

Abstract: A monitoring system for providing an accurate indication of a patient's respiration rate. The system is effective in eliminating or significantly reducing the effects of heart sounds and ambient noise. The system comprises means for obtaining a first signal waveform containing components corresponding to the patient's breath sounds, as well as components corresponding to heart sounds and ambient noise. The signal is passed through a digital bandpass filter having a passband selected to remove heart sounds and ambient noise to produce a second waveform. From the second waveform the total energy is computed of a portion of the signal within a moving window of predetermined length. The resulting energy envelope signal is smoothed and then high-pass filtered by removing the average DC value of the signal over a predetermined preceding time interval. Respiration is detected by identifying significant, positive-going zero crossings of the resulting signal through a band about zero.

Abstract: A system for positioning a tonometric sensor array over an artery on a patient's wrist such that minimal hold down pressure is required to flatten said artery. The preferred embodiment of the invention comprises a sensor case which can be attached to a patient's wrist in a manner similar to a conventional wristwatch. A transducer piston is received in the case and is movable therein. A protrusion in the lower face of the transducer piston defines a sensor mounting platform. A sensor comprising an array of pressure sensing elements is attached to the mounting platform such that the operative face of the sensor is offset from the lower surface of the piston by a predetermined distance. The sensor platform has a shape which allows part of it to fit between the radius bone and the flexor tendon in the patient's wrist. The required hold down pressure is provided by a pressurizable bellows.

Abstract: A pressurization system for a continuous blood pressure monitor transducer. The system comprises dual chamber compression apparatus and a switching mechanism, both of which are engaged with a servo motor drive mechanism. The drive mechanism simultaneously controls the compression apparatus and the switching mechanism, thereby coordinating flow of air from the compression chambers to the pressurizable chamber within the transducer. A detachable connector permits simultaneous interruption of air flow and the control signals to the drive mechanism.

Abstract: A method and apparatus for detection of coronary artery disease. The apparatus records and analyzes that portion of the phonocardiogram lying between about 100 to 600 Hz. An electrocardiogram is also recorded and examined in order to pinpoint the diastolic window of PCG data. This window of data is subject to autocorrelation analysis and spectral analysis, resulting in a partial correlation coefficient index and a power density index. A linear combination of these two indices results in a Cardiac Screening Index which is indicative of the presence or absence of coronary artery disease.

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 method for computing optimal hold down pressure for a transducer comprising an array of pressure sensing elements for generation of electrical waveforms indicative of blood pressure in an artery. Using the selected pressure sensing element that is determined to be positioned substantially over the center of the underlying artery, a set of data corresponding to the diastolic pressure and the pulse amplitude pressure is collected and stored. The diastolic pressures and pulse amplitude pressures are taken as a function of hold down pressure over a range of hold down pressures between the pressure at which the artery is unflattened and the pressure at which the artery is occluded. First and second polynomials are fitted to the diastolic pressure data set and the pulse amplitude data set, respectively. The hold-down pressure at the point of minimum slope of the first polynomial fitted to the diastolic versus hold-down pressures values provides one estimate of the correct hold-down pressure.

Abstract: A system for automatically positioning a blood pressure monitor transducer in a desired position relative to an underlying artery. The positioning system comprises a positioniong motor which drives a gear assembly. The gear assembly is operatively engaged with a lead screw having a follower mounted thereto in threaded engagement therewith. The follower is secured to a strap which is routed through a roller system. As the motor is activated in response to output signals from the sensor mounted within transducer housing, the lead screw will rotate, thereby effectuating lateral movement of the transducer housing and sensor along a path defined by the strap.

Abstract: A non-invasive method and apparatus for measuring the volume of an object such as an infant using the principle of the Helmholtz resonator. A container having a cavity therein containing gas and having an opening is subjected to a variable frequency loud speaker. The resonance frequency of the cavity is proportional to the volume of the cavity. By placing an object to be measured in the cavity, the change in the resonance frequency of the cavity before and after the object is placed is an indication of the volume of the object. The loudspeaker is mechanically uncoupled from the opening, the volume of the cavity is large enough compared to the object to be measured so the object will not change the shape of the cavity, and the temperature inside the cavity is maintained substantially constant during the measurements. Various lung measurements may be taken by determining the volume of air inhaled or exhaled from the lungs of an animal.