Abstract: An ambulatory blood pressure monitor comprises a cuff coupled by a single fluid passageway to a manifold which in turn is coupled to a pump, valve and pressure transducer. The manifold comprises a larger main chamber in fluid communication with a smaller secondary chamber through a small channel in a wall separating the chambers. The pump, cuff and valve are in fluid communication with one another directly through the main chamber while the pressure transducer is coupled to the cuff through the secondary chamber.

Abstract: A portable recorder has a pinch roller moved to engage a capstan, a recording head brought into a recording position and a motor to power the recorder switched on through the sliding movement of a slide assembly in engagement with the case of the recorder near a hinge between bottom and top portions of the case. The capstan is rotated about an axis substantially perpendicular to the plane of the case by a pulley arrangement driven by the motor with an axis substantially within a plane parallel to the case. The recording head is mounted to the slide assembly which includes a roller attached to the back thereof for rotating engagement with the case when it is opened and closed. Rotating movement of the roller causes the slide assembly to move back and forth within the case as the top of the case is opened and closed causing the recording head to move near or away from the tape. A spring mounted to the case and the slide assembly biases the slide assembly to a remote position when the case is opened.

Abstract: A connector and sampling line for obtaining sample gases from a patient's exhaled gas stream present in an air tube coupled to the patient is disclosed. The sampling line comprises a sampling end portion having an open end and at least one hole in a wall of the end portion. A tubular shaped connector through which the gas stream passes along a first path includes a hollow cylinder coupled to the wall of the connector and protruding therefrom. The hollow interior of the connector communicates with ambient atmosphere through a distal open end and to the interior of the tubular portion of the connector through a hole in the connector wall. The sampling line includes a reinforced portion adjacent the sampling end portion for reinforcement. The hollow cylinder has an interior diameter large enough to receive the reinforced portion and substantially larger than the hole in the connector wall which hole is large enough to receive the sampling end portion.

Abstract: An apparatus and method for smoothing the reproduction of digitized waveforms on a raster scan line display by providing control signals which increase and decrease the electron beam pattern along the scan line in a trapezoidal pattern which is representative of the amplitude of the sampled waveform along that scan line. A microprocessor provides a plurality of digital signals which define the slopes of the increasing and decreasing ramps of the trapazoids and their starting points along the scan line. The digital signals for an entire frame of scan lines are stored during the frame blanking interval of the display and are accessed for each scan line during the scan line blanking interval. The digital signals are stored in a random access memory (RAM) at raster scan line addresses provided by the processor through a scroll counter and at digital signal addresses provided through a display controller.

Abstract: A crossed light beam coordinate detection and encoding system having a plurality of emitter/detector pairs along each axis of the display space is disclosed. The emitters are modulated in amplitude and the detectors are biased with a low load resistance to provide a wide dynamic range. The wide dynamic range and amplitude modulation detection provides immunity to unwanted interference. After band pass filtering, the carrier is amplified by high gain amplifier with auto bias control. The output of the amplifier generates a true/false output corresponding to the presence/absence of a beam. A single chip microprocessor controller checks the screen for interrupted beams and when not clear generates coordinates of the interrupted beams. The coordinates can be calculated as a weighted average of the interrupted beams for each axis or as the min and max coordinates along each axis. Reporting is done repeatedly at preselected time intervals.

Abstract: A power supply circuit for an output stage portion of a magnetic deflection circuit amplifier is disclosed. It comprises a power supply means for supplying a supply voltage during the collapse of the magnetic field associated with the yoke following the retrace portion. The power supply means also restores energy to another power supply means to which it is coupled, the other power supply means providing a supply voltage to the amplifier during a portion of the raster scan just preceding the retrace.

Abstract: A crossed light beam coordinate detection and encoding system having a plurality of emitter/detector pairs along each axis of the display space is disclosed. The emitters are modulated in amplitude and the detectors are biased with a low load resistance to provide a wide dynamic range. The wide dynamic range and AM modulation detection provides immunity to unwanted interference. After band pass filtering, the carrier is amplified by high gain amplifier with auto bias control. The output of the amplifier generates a true/false output corresponding to the presence/absence of a beam. A single chip microprocessor controller checks the screen for interrupted beams and when not clear generates coordinates of the interrupted beams. The coordinates can be calculated as a weighted average of the interrupted beams for each axis or as the min and max coordinates along each axis. Reporting is done repeatedly at preselected time intervals.

Abstract: A method for dynamically assigning addresses to new modules as they are coupled to a communication system with a synchronous data link control (SDLC) bus is described. These modules communicate with a display unit via the SDLC bus. The SDLC bus is controlled by a primary station in the display unit, with all modules acting as secondary stations. The primary station periodically broadcasts a time-tag to all modules at a thirty-two hertz rate. At power up, each module obtains a number, module 16, derived from the lower four bits of its unique twenty-four bit serial number. The module uses this number as a count of the number of time-tags which must occur before the module responds to the primary with an address request. If there are no collisions with other modules, the primary sends the module a packet which assigns the module the next available address. In the event of a collision (i.e.

Abstract: A method and apparatus for automatic rhythm analysis of digitized ECG signals. Candidate heartbeats are detected and the noise of the ECG signal portion containing the candidate is evaluated to determine whether the candidate is a valid nominal or noisy beat or an invalid noisy saturated signal. The timing of detected heartbeats, both noisy and nominal, are determined relative to prior validated heartbeats. Features of the detected heartbeats are automatically extracted including onset, offset and R wave locations; QRS complex width; R-R interval based on the onset points; instantaneous and averaged heartrates; and others. A 16 point template of the heartbeat starting at the onset is also determined. Beats are then classified in a two step process; first, by template comparison with a previously determined dominant template, and second, by a finite state machine process based on the results of the template comparison and relative timing of the beat.

Abstract: An amplifier circuit with serially coupled output stages coupled to different level voltage supplies wherein at least the higher voltage-supplied output stages comprise a field effect transistor (FET) device is disclosed. In one embodiment a floating power supply is coupled between V.sub.in and the gate of the FET to provide turn on of the FET at the proper crossover voltage. In another embodiment, control of the FET is provided by a transistor circuit which causes the FET to turn on in response to the instantaneous voltage drop across the lower voltage-supplied output stage.

Abstract: An ECG electrode impedance measuring approach is utilized which can determine, simultaneously, the condition of all electrodes in a three or five lead ECG monitoring configuration. A CPU automatically selects an ECG lead configuration in which all electrodes are attached to the patient and are below an impedance threshold. If the CPU cannot select a good ECG lead configuration, then the CPU signals a total lead failure. Electrode impedance is determined by passing a small DC current through each active electrode and the current is returned via the reference electrode. A comparator tests the resultant offset voltage induced between each active electrode and the reference. If the offset voltage exceeds a fixed threshold, then a flag is set and transferred to the CPU. The CPU can change the ECG lead configuration by issuing commands to an electrode lead switching network.

Abstract: An apparatus and method for providing a sample gas flow from an air tube of a patient undergoing automatic ventilation is disclosed. The air tube includes a gas diffusive membrane disposed in a wall of the air tube. The base of a funnel member is disposed to engage the air tube at the membrane, the area of the base substantially equal to the area of the membrane. The funnel member includes a tubular end portion opposite the base which end portion is disposed to be coupled to a sampling tube or gas monitoring equipment. Cross sectional area of the tubular end portion is substantially smaller than the area of the base. A pump in the gas monitoring system is coupled to the tubular end portion and causes a small portion of the gas in the air tube to pass through the membrane into the funnel. The velocity of the sample gas flow through the membrane is lower than the velocity through the tubular end portion but the sample gas flow rate remains constant.

Abstract: The amplitude of each R wave of an electrocardiogram signal at each of a plurality of sample points is compared with reference values representing amplitudes of a reference template at the sample points, with each new set of R wave amplitudes at the test points being applied to update the reference values by being averaged therewith. The amplitudes of each R wave which has been determined to differ from the reference template at at least one of the test points are stored in a recirculating shift register memory in addition to being compared to other values previously stored in the memory. Whenever a set of amplitudes is determined to be equal to a set of amplitudes previously stored in the memory, an alarm signal is generated to identify an arrhythmia.