Abstract: A method for determining a dominant heart rate from a series of beat triggers representative of a mixed series of normal heart beats and non-arrhythmic activities, with the beat triggers being determined at a specific sampling rate defining sample intervals, comprising the steps of: framing a window to include a portion of the series of beat triggers and to be beat-aligned with a first beat trigger and a last beat trigger, the window thereby defining a plurality of trigger intervals for respective adjacent beat triggers, with each trigger interval containing a plurality of the sample intervals existing between the respective adjacent beat triggers; summing the windowed sample intervals; for each of the trigger intervals, computing a weight factor based upon the ratio of the summed windowed sample intervals to the number of sample intervals within that trigger interval; grouping the trigger intervals according to the weight factors; computing the percentage of the window that each group of weight factors const

Abstract: This invention relates to a novel needle for expeditiously determining proper insertion of the needle into a patient. A transparent shaft is positioned behind the tip of the needle. Upon insertion of the needle into the vein of a patient, blood is observed in the transparent shaft of the needle. Preferably, the shaft is formed of polyurethane or polycarbonate the needle can be used with an over-the-needle catheter.

Abstract: A method and apparatus are described for determining characteristics of peripheral arterial volume and compliance. A blood pressure cuff is inflated and deflated around a limb of the body and pressure measurements are taken. The volume of air removed from the cuff is determined in a quantifiable manner, such as by expelling air through an orifice of known characteristics or by means of a volume of know characteristics. The detected pressures and volume of air, removed are used to compute oscillation volume, which in turn is used to display arterial capacity and compliance as a function of transmural pressure and time. Arterial capacity may be displayed in terms of arterial radius, arterial cross-sectional area, or arterial volume. A display of these characteristics as a function of pre and post anesthetic administration is particularly useful to the anesthesiologist and surgeon.

Abstract: A patient monitoring system includes a pulse oximeter sensor and an audible alarm which is not produced when a blood pressure module is taking measurements, but only during that portion of the cycle that affects the pulse oximeter reading. During such measurements, the pulses detected by the oximeter decrease below a threshold T.sub.oxim. An audible alarm is caused to receive a logic level of zero by an AND gate through the detection of measurements exceeding a minimum pressure P.sub.min on the blood pressure module. The audible alarm continues to receive such a logic level until the measurements exceed a threshold P.sub.thr. After that time, the audible alarm AND gate logic level is reset to one, so as to permit reporting of pulses missing at the oximeter. None of the other alarms, such as the actual SPO.sub.2 reading, are affected by the AND gate. Accordingly, the present invention does not affect the taking of important SpO.sub.

Abstract: An anesthetic agent analyzer having six or more independent analytical channels, where each channel comprises a first thermopile which receives incident infrared radiation and a second thermopile behind the first thermopile which is blocked from the incident infrared radiation and thus serves as a reference for detecting ambient temperature variations. The first and second thermopiles are connected in a "parallel opposed" fashion so that the effects of ambient temperature variations automatically cancel and the detectors may be readily configured in a detector package. The anesthetic agent analyzer of the invention is designed for use with a wideband infrared radiation source so that anesthetic agents having characteristic absorption bands in the far infrared wavelength range (6-15 microns) may be more readily detected and discriminated.

Abstract: An infrared gas analyzer implementing an optically stabilized detector in a sidestream configuration. In order to reduce the pneumatic sampling volume, an "optical funnel" or collimator is used to resize the optical aperture of a multi-channel optically stabilized detector without compromising signal strength. The smaller pneumatic volume is desirable in order to minimize the time required for a gas wavefront from the sample cell to traverse the optical aperture, thereby minimizing pneumatic response time. The geometry of the sample cell of the invention is also streamlined so that sharp corners or transitions which might induce turbulent gas flow are eliminated. The sample cell of the invention thus promotes smooth, laminar flow of aspirated respiratory gases through the optical aperture so as to preserve the temporal relationship of gas concentration wavefronts within the gas stream and to thereby allow the analyzer to exhibit a faster pneumatic response.

Abstract: Methods and apparatus for constructing optically stabilized, shutterless infrared capnographs are disclosed. The capnographs of the present invention provide the absolute concentration of the constituents of the respiratory airstream of a patient, without the thermal drift problems normally associated with thermopile detectors, thereby providing a device with a high degree of accuracy. The present invention eliminates the need for a mechanical shutter to modulate the incident infrared beam and the need for a modulated source, thereby increasing the reliability and response time of the devices disclosed. Capnographs which are substantially unaffected by changes in the ambient temperature at which they operate are provided by connecting pairs of optically filtered thermopiles in series and processing the resulting differential pair. In addition, techniques are provided for selecting overlapping optical filters for use with thermopiles with a minimum level of cross-talk.

Abstract: A patient monitoring system includes a pulse oximeter sensor and an audible alarm which is not produced when a blood pressure module is taking measurements, but only during that portion of the cycle that affects the pulse oximeter reading. During such measurements, the pulses detected by the oximeter decrease below a threshold T.sub.oxim. An audible alarm is caused to receive a logic level of zero by an AND gate through the detection of measurements exceeding a minimum pressure P.sub.min on the blood pressure module. The audible alarm continues to receive such a logic level until the measurements exceed a threshold P.sub.thr. After that time, the audible alarm AND gate logic level is reset to one, so as to permit reporting of pulses missing at the oximeter. None of the other alarms, such as the actual SpO.sub.2 reading, are affected by the AND gate. Accordingly, the present invention does not affect the taking of important SpO.sub.

Abstract: An infrared source which provides a miniature, highly stable and efficient source of infrared energy for use with infrared detectors and the like. The infrared source of the invention incorporates a platinum resistance temperature detector (RTD) which is integrated with the heater element to provide a means of electronic servo control of the heater temperature. The heater element and the RTD are tightly coupled thermally to provide accurate, continuous tracking and control of the heater temperature. The infrared source design provides excellent infrared energy output with less than one watt input power to the heater.

Abstract: A method and apparatus are described for determining characteristics of peripheral arterial volume and compliance. A blood pressure cuff is inflated and deflated around a limb of the body and pressure measurements are taken. The volume of air removed from the cuff is determined in a quantifiable manner, such as by expelling air through an orifice of known characteristics or by means of a volume of know characteristics. The detected pressures and volume of air removed are used to compute oscillation volume, which in turn is used to display arterial capacity and compliance as a function of transmural pressure and time. Arterial capacity may be displayed in terms of arterial radius, arterial cross-sectional area, or arterial volume. A display of these characteristics as a function of pre and post anesthetic administration is particularly useful to the anesthesiologist and surgeon.

Abstract: One-way intravenous catheter assembly provided with a tubular needle guard slidable with respect to the needle housing, so as to completely cover the needle both before and after use, said needle housing comprising a substantially cylindrical central body with a flash chamber and a tapered front portion, to which the catheter needle is attached, and a peripheral finger gripping element, connected to the central body but extending around the tubular needle guard, the connection being provided by a connecting element which is slidable in a longitudinal slot of the tubular needle guard, the catheter assembly being further provided with a catheter tube or cannula mounted around the needle and provided with a hub for engagement with said tapered front portion of the needle housing.

Abstract: A method and apparatus for non-invasively measuring blood constituent concentration and particularly the oxygen saturation of arterial blood. The apparatus includes at least one light source directed to a tissue area of a patient, such as a finger or earlobe. A photodetector receives emitted light passing through the sample, and a receiver circuit analyzes the data and produces an output which is proportional to the oxygen content of blood. The light source is modulated onto a preselected carrier frequency and the receiver circuit is tuned to the carrier frequency so that undesired signals such as ambient light can be filtered out leaving only the signals created by the emitted light passing through the tissue at the light source frequency. The oxygen content is then calculated using the patient's known red cell count, thereby correcting the final saturation value for patient anemia.

Abstract: A care management workstation unit which contains three basic elements. There is a cathode ray tube or CRT, a mount, and a system unit. The CRT is rotatably mounted on the mount. It is capable of any rotational position and is able to be balanced at all such positions. The CRT is unique in that it is integral to the system. The mount connects the CRT to the system unit. It is able to be mounted flush against a wall such that the entire unit is supported by the mount. The system unit is also flush with the wall and the wall mount so that the entire system may be placed for mounting against a wall. In all, these three devices combine into one system to provide for a powerful, compact and ergonomically successful device which enables one to use the system virtually anywhere within a hospital or industrial setting.

Abstract: A blood pressure cuff is applied about a subject's artery, and inflated above the systolic level thus fully occluding the artery for a full heart cycle. The cuff pressure is thereafter reduced to permit an increasing flow through the progressively less occluded artery, and a measure of the peak amplitudes of the successively encountered blood pressure (oscillatory complex) pulses stored in memory. Also retained is the cuff pressure obtaining for each stored complex peak. In accordance with varying aspects of the present invention, the stored complex peak-representing data ensemble is corrected for aberrations; and improved data processing operates on the stored (and advantageously corrected) pulse peak data and the corresponding cuff pressure information to determine the subject's systolic arterial blood pressure.

Abstract: A catheter is provided which deters the backflow of blood between the insertion needle and the catheter cannula by forming the distal end of the catheter hub so as to restrict the inner diameter of the catheter cannula to a wiping fit with the engaged insertion needle. In a first embodiment the distal end of the catheter hub is pre-formed to its desired final inner dimension. The distal end of the hub is stretched to an oversize condition, the catheter cannula is attached to the hub, and the distal end of the catheter hub is heated, causing a stress relief of the previously stretched hub. The distal end of the catheter hub returns to its pre-formed dimension which will mechanically restrict the diameter of the catheter cannula at that point to form the wiping fit with the engaged needle.

Abstract: A catheter device is described with a safety needle guard that covers and protects the needle after use of the device. The device includes a semi-tubular needle housing containing a flash chamber with a hollow needle extending from the distal end of the flash chamber. A tubular needle guard concentrically fits and slides within the needle housing. The needle guard has a longitudinal slot through which the mounting base of the flash chamber passes as the guard slides within the housing. The top of the semi-tubular housing is open so that a user may access the top of the tubular needle guard with a finger to urge the needle guard to an extended position from the distal end of the housing and in a surrounding position about the needle. The proximal end or hose of the needle guard detaches for the needle housing and has a luer fitting for an infusion set. The catheter hub contains a lever capable of occluding the catheter to inhibit fluid flow.

Abstract: An I.V. catheter is described, including a catheter and hub assembly and a needle and hub assembly. A needle guard, including a tubular distal portion and a split proximal flange, is located about the needle at the distal end of the needle hub. The needle includes a slot near the needle tip. As the needle assembly is withdrawn from the catheter, the needle guard slides along the needle until the split flange engages the needle slot, which locks the tubular distal portion of the guard over the needle tip.