Abstract: A system and a method for switching antenna fields without waiting until data packets containing errors are detected. This is accomplished by monitoring the signal power for each antenna field immediately after receipt of data packets via the currently active antenna field and then switching to another antenna field having greater signal power. A communications channel is provided which has a capacity greater than that required by the data to be transmitted. This extra capacity is used to introduce time periods when no data is being transmitted. During these time periods, known bit patterns are transmitted, and the signal power during receipt of each of these blank packets is estimated for each antenna field. The receiver then switches to the most appropriate antenna field based on highest signal power (e.g., based on a weighted average for the N-th most recent sample periods) and continues to receive the transmitted data without interruption.

Abstract: A patient monitoring system comprising a central station for analyzing and displaying patient data; a system receiver connected to the central station; and an antenna array connected to the system receiver and including a plurality of antennae, each having connected thereto a respective transmitter.

Abstract: A method of detecting heart beat coincidence includes receiving first and second signals from first and second heart beat sources. The method further includes detecting first heart beat occurrences on the first signal, each first heart beat occurrence having a respective time associated therewith and detecting second heart beat occurrences on the second signal, each second heart beat occurrence having a respective time associated therewith. The method further includes comparing the times of the first and second heart beat occurrences to detect coincidence.

Abstract: A method and apparatus of storing and accessing data from a database is disclosed. The method and apparatus applies particularly to database systems used for cardiovascular information systems but may also be used in other database systems. The method and apparatus for storing and accessing data utilizes a markup language tag data structure to provide for simplified and expedited searching over conventional databases.

Abstract: A cable management and data acquisition method and apparatus to store system data and data from activity sensors when the sensors are disconnected from a monitoring system. The apparatus includes a housing, a first connection port operable to receive information from one or more activity sensors, a device interface coupled to the first connection port, a non-volatile memory coupled to the device interface; and an output port coupled to the device interface. The cable management and data acquisition apparatus may also include a digital-to-analog converter to convert analog signals from sensors to digital signals. Preferably, the device interface is an application specific integrated circuit (“ASIC”) that communicates with a signal processor in the monitoring processor. The signal processor responds to commands or messages from the monitoring processor and reads data from and writes data to the memory in the cable management and data acquisition apparatus through the ASIC.

Abstract: In order to reduce bias associated with conventional ECG analysis, the present invention provides a method and apparatus to improve diagnosis of acute cardiac syndromes (ACS), such as acute myocardial infarction and acute cardiac ischemia (unstable angina), in specified groups of patients using ECG signals and automatic detection analysis. Specific criteria are developed and utilized based on a prespecified group selection for the particular patient. After identifying group membership for the particular patient, ECG data are acquired from a patient experiencing ACS symptoms. Known criteria typically used for assessing ACS are then modified for the particular group membership. Such criteria significantly reduce the bias found in a baseline group for which the known criteria were established.

Abstract: A system for selecting physiological data from a plurality of physiological data sources includes first and second physiological data sources and a selection algorithm. The first physiological data source is configured to provide first physiological data. The first physiological data includes a first measurement of a physiological trait. The second physiological data source is configured to provide second physiological data. The second physiological data includes a second measurement of the physiological trait. The first and second measurements are based on different physiological characteristics. The selection algorithm is configured to receive the first and second physiological data and to select one of the first and second measurements as the output data for the physiological trait based on at least one of the first physiological data and the second physiological data.

Abstract: A liquid and gas separator system is disclosed, the liquid and gas separator system includes an inlet that receives a first gas sample. The first gas sample at least partially includes liquid introduced from a patient in a gaseous or liquid form. The liquid and gas separator system also includes a first chamber coupled to the inlet and configured to receive the first gas sample. The first chamber includes a drain aperture. An outlet is coupled to the first chamber and is configured to receive a second gas sample from the first chamber. The second gas sample is derived from the first gas sample, that is the second gas sample includes less liquid than the first gas sample. The second chamber is substantially sealed around the first chamber. The first chamber receives a combined gas and liquid from the inlet and separates at least some of the liquid from the gas. The first chamber is configured to have liquid deposited at the bottom of the first chamber.

Abstract: A method of stabilizing temperature effects on a gas analyzer includes transmitting infrared energy through a plurality of cells in a reference cell drum to a sensor in the gas analyzer. The plurality of cells include at least one cell containing a reference gas and at least one cell containing an air reference. The method also includes interposing a filter in at least one of the plurality of cells in the reference cell drum, wherein energy from the infrared beam is reduced. The method further includes rotating the reference cell drum such that the infrared energy fully passes through each of the plurality of cells for a limited period of time such that the sensor generates a substantial sine wave signal.

Abstract: An ECG signal is acquired in multiple channels, and sources of interference are filtered from the signals. A covariance matrix is then formed with the channels of data. The invention then employs matrix mathematics to discover a set of eigenvectors that organize the variability of data in a multi-dimensional space along new directions, orthogonal to each other and ranked in order of significance. For each eigenvector, a corresponding eigenvalue is calculated. In addition, coefficients are calculated which correspond to the portion of each eigenvector that is necessary to reconstruct each original vector. From the eigenvector solution of the covariance matrix, the angles between the eigenvectors and the original vectors are determined. The eigenvector coefficients and the angles between the eigenvectors and the original vectors are related by a cosine relationship.

Abstract: A method and an apparatus for informing a system user of the remaining battery terminal voltage as the battery approaches the fully discharged condition. One horizontal fuel gauge icon for each battery is displayed on the host system display panel. The fuel gauge is displayed as two overlapping rectangles which are left justified. The first layer is a solid outline, always the same width, representing the full charge capacity of the battery. The second layer is a filled-in rectangle representing the present (actual) charge capacity as a percentage of the full charge capacity in a charge depletion mode and representing the battery terminal voltage in a voltage mode. The fuel gauging switches from the charge depletion mode to the voltage mode is response to detection of a battery terminal voltage threshold greater than a shutdown voltage threshold.

Abstract: The combination of a pressure control and a catheter including an elongate member, a sensor mounted on the catheter and adapted to be placed in pressure engagement with tissue for sensing signals resulting from physiological phenomena and an expandable member mounted on the elongate member for maintaining the sensor in contact with the tissue. A pressure source is connected to the expandable member for maintaining the expandable member inflated and a pressure controller coupled to the expandable member for maintaining the contact pressure between the sensor and the tissue within preselected limits.

Abstract: A maternal blood pressure measuring method including the steps of periodically initiating a maternal blood pressure measurement, sensing uterine activity, preventing the initiation or continuation of a blood pressure measurement during uterine contraction, initiating a blood pressure measurement upon the cessation of uterine contractions and a processor programmed to perform these functions.

Abstract: A test stand for use in testing the performance of an X-ray system constructed and arranged to project an X-ray beam along a defined path. The stand includes a vertical base, a first support extending horizontally from one end of the base for positioning a first test object at a first location relative to the path and a second support extending horizontally from the other end of the base for positioning a second test object at a second position relative to said path and spaced from said first test object. Each support includes a test object receiver and one of the receivers is adjustable in a direction perpendicular to the path. A leveler is mounted on the stand for leveling the first and second supports relative to the horizontal. Each of the supports is pivotally mounted on the base and holding members are coupled to the base and the supports for holding each of said supports in a horizontal orientation, the holding members being releasable to permit the supports to be pivoted toward the frame for storage.