Abstract: A memory in a sensor is used to store multiple coefficients for a physiological parameter. In one embodiment, not only are the sensor's specific calibration coefficients stored in a memory in the sensor for the formula to determine oxygen saturation, but multiple sets of coefficients are stored. The multiple sets apply to different ranges of saturation values to provide a better fit to occur by breaking the R to SpO2 relationship up into different pieces, each described by a different function. The different functions can also be according to different formulas for determining oxygen saturation.

Abstract: A method and apparatus for reducing the effects of noise on a system for measuring physiological parameters, such as, for example, a pulse oximeter. The method and apparatus of the invention take into account the physical limitations on various physiological parameters being monitored when weighting and averaging a series of measurements. Varying weights are assigned different measurements, measurements are rejected, and the averaging period is adjusted according to the reliability of the measurements. Similarly, calculated values derived from analyzing the measurements are also assigned varying weights and averaged over adjustable periods. More specifically, a general class of filters such as, for example, Kalman filters, is employed in processing the measurements and calculated values. The filters use mathematical models which describe how the physiological parameters change in time, and how these parameters relate to measurement in a noisy environment.

Abstract: A memory in a sensor is used to store multiple coefficients for a physiological parameter. In one embodiment, not only are the sensor's specific calibration coefficients stored in a memory in the sensor for the formula to determine oxygen saturation, but multiple sets of coefficients are stored. The multiple sets apply to different ranges of saturation values to provide a better fit to occur by breaking the R to SpO2 relationship up into different pieces, each described by a different function. The different functions can also be according to different formulas for determining oxygen saturation.

Abstract: A sensor has codes useful for a monitor which can be authenticated as accurate. The sensor produces a signal corresponding to a measured physiological characteristic and provides codes which can be assured of being accurate and authentic when used by a monitor. A memory associated with the sensor stores both data relating to the sensor and a digital signature. The digital signature authenticates the quality of the code by ensuring it was generated by an entity having predetermined quality controls, and ensures the code is accurate.

Abstract: A pulse oximeter sensor having an emitter(s) and a detector, with a layer having a first portion of the emitter and a second portion of layer over the detector is provided. A barrier is included between the first and second portions of the overlying layer to substantially block radiation of the wavelengths emitted by the emitter(s). Preferably, the barrier reduces the radiation shunted to less than 10% of the radiation detected, and more preferably to less than 1% of the radiation detected.

Abstract: A headband with a tension indicator having an elastic segment sized to fit around a wearer's head; and a non-elastic segment being smaller than and attached with the elastic segment. The non-elastic segment is sized to span a portion of the elastic segment when the elastic segment is stretched, and the non-elastic segment is larger than the portion of the elastic segment it spans when the elastic segment is not stretched. The non-elastic segment is attached with the elastic segment in such a manner that the non-elastic segment projects out from the surface of the elastic portion when the headband is not sufficiently tight, thus creating a loop which provides a visual indication that the headband needs re-tightening.

Abstract: A method and apparatus for controlling alarms in a medical diagnostic apparatus where an alarm is generated when a measured value for a physiological parameter is outside a specified range. The method continuously calculates a baseline value, and establishes dynamic thresholds that are related to and continuously track the baseline value. The method determines the amount of time the measured value is past the dynamic threshold, and the amount by which the threshold is passed. Alarms are triggered based upon a combination of the amount of time and the amount by which the threshold is passed. Preferably, the combination is an integral or some function of an integral.

Abstract: An optical sensor having a cover layer, an emitter disposed on a first side of the cover, a detector disposed on the first side of said cover, and a plurality of stacked independent adhesive layers disposed on the same first side of the cover, wherein the top most exposed adhesive layer is attached to a patient's skin. Thus, when the sensor is removed to perform a site check of the tissue location, one of the adhesive layers may also be removed and discarded, exposing a fresh adhesive surface below for re-attachment to a patient's skin. The independent pieces of the adhesive layers can be serially used to extend the useful life of the product.

Abstract: A parameter of interest being measured by a sensor is estimated from output response data from the sensor and the known transfer function of the sensor, allowing fast and accurate sensor data from sensors having a dynamic characteristic otherwise precluding assessment of the sensor input. A parameter of breathing gas from a ventilator is determined based upon the known transfer function and a plurality of the sensor output signals at predetermined intervals of time, to provide an estimation of the parameter of interest.

Abstract: The system and method for graphic creation of a medical logical module in the Arden syntax file format allows a user to define a medical decision process in terms of flowcharts and outlines. The system and method provide for creation of a medical logical module for a computer in the Arden syntax file format. A graphic representation of a medical decision logic tree of a connected series of a plurality of nodes in a medical decision process is encoded, with each node having a logical path from the node, and each connected series of nodes containing at least one intermediate node and a concluding node. For each node, a conditional statement is encoded for each path from the node; a definition of a path for each intermediate node is encoded; and an outcome for each concluding node is encoded.

Abstract: A method and apparatus for reducing the effects of noise on a system for measuring physiological parameters, such as, for example, a pulse oximeter. The method and apparatus of the invention take into account the physical limitations on various physiological parameters being monitored when weighting and averaging a series of measurements. Varying weights are assigned different measurements, measurements are rejected, and the averaging period is adjusted according to the reliability of the measurements. Similarly, calculated values derived from analyzing the measurements are also assigned varying weights and averaged over adjustable periods. More specifically, a general class of filters such as, for example, Kalman filters, is employed in processing the measurements and calculated values. The filters use mathematical models which describe how the physiological parameters change in time, and how these parameters relate to measurement in a noisy environment.

Abstract: A sensor has codes useful for a monitor which can be authenticated as accurate. The sensor produces a signal corresponding to a measured physiological characteristic and provides codes which can be assured of being accurate and authentic when used by a monitor. A memory associated with the sensor stores both data relating to the sensor and a digital signature. The digital signature authenticates the quality of the code by ensuring it was generated by an entity having predetermined quality controls, and ensures the code is accurate.

Abstract: A method and apparatus for the application of Blind Source Separation (BSS), specifically independent Component Analysis (ICA) to mixture signals obtained by a pulse oximeter sensor. In pulse oximetry, the signals measured at different wavelengths represent the mixture signals, while the plethysmographic signal, motion artifact, respiratory artifact and instrumental noise represent the source components. The BSS is carried out by a two-step method including an ICA. In the first step, the method uses Principal Component Analysis (PCA) as a preprocessing step, and the Principal Components are then used to derive sat and the Independent Components, where the Independent Components are determined in a second step. In one embodiment, the independent components are obtained by high-order decorrelation of the principal components, achieved by maximizing the sum of the squares of the higher-order cumulants of the plurality of mixture signals.

Abstract: A vent system for an infusion drip chamber is provided according to the invention. The vent system includes an automatic air eliminator communicating with an interior and an exterior of the infusion drip chamber. The automatic air eliminator is capable of automatically venting air from the infusion drip chamber in a substantially continuous manner. The vent system further includes a mechanical air eliminator communicating with the interior and the exterior of the infusion drip chamber. The manual air eliminator is capable of mechanically venting air from the infusion drip chamber at discrete time intervals.

Abstract: The present invention relates to a method and apparatus for improving the durability of a sensor, specifically one attached by an adhesive material to a subject. Specifically, the present invention discloses a method and apparatus for laminating a sensor and inserting the sensor into a protective shield for use. The shield includes some adhesive material to affix the sensor to the subject. A dirty, damaged, or worn out shield may be discarded and the sensor inserted into a new shield for continued use of the sensor.

Abstract: The invention is directed to a ventilation control system for controlling the ventilation of a patient. The ventilation control system utilizes a user-friendly user interface for the display of patient data and ventilator status. The user interface includes a graphic representation of a breath cycle that displays the breath cycle currently being ventilated, and is also responsive to changes in ventilation settings to assist the user in evaluation the effect of those changes on the ventilator strategy before the changes are implemented.

Abstract: An intrauterine pulse oximetry apparatus and method are provided to measure fetal blood oxygen saturation at sites in a preferred region on the fetus. The sensor of the apparatus is attached to a stiff cable which can be inserted into the uterus past the presenting part and transcervical region of the fetus. The cable may have visual and tactile markings by which the user, without seeing or feeling the sensor, can guide it to an appropriate site on the fetus.

Abstract: The system and method for detecting disconnection and occlusion of a tubing system of a patient ventilator detects disconnection of the tubing system, opens the exhalation valve, delivers an idle flow of breathing gas to the tubing system, disables breath triggering, and generates an alarm. A reconnection of the tubing system can also be detected, to initiate resumption of pressure supported inspiration. For occlusion detection, the pressure drop in the tubing system is determined by pressure sensors in the inspiratory and expiratory airways of the tubing system. The two pressure drop values are compared, and once occlusion is detected, an alarm is generated, and the ventilator responds to protect the patient from over distension. Abatement of the occlusion can also be monitored in a pressure based occlusion status cycling mode, and the ventilator can revert back to normal ventilation when either circuit occlusion or exhaust port occlusion are not detected.

Abstract: A device and a method to provide a more reliable and accurate measurement of hematocrit (Hct) by noninvasive means. The changes in the intensities of light of multiple wavelengths transmitted through or reflected light from the tissue location are recorded immediately before and after occluding the flow of venous blood from the tissue location with an occlusion device positioned near the tissue location. As the venous return stops and the incoming arterial blood expands the blood vessels, the light intensities measured within a particular band of near-infrared wavelengths decrease in proportion to the volume of hemoglobin in the tissue location; those intensities measured within a separate band of wavelengths in which water absorbs respond to the difference between the water fractions within the blood and the displaced tissue volume. A mathematical algorithm applied to the time-varying intensities yields a quantitative estimate of the absolute concentration of hemoglobin in the blood.

Abstract: The present invention relates to a method and apparatus for improving the durability of a sensor, specifically one attached by an adhesive material to a subject. Specifically, the present invention discloses a method and apparatus for laminating a sensor and inserting the sensor into a protective shield for use. The shield includes some adhesive material to affix the sensor to the subject. A dirty, damaged, or worn out shield may be discarded and the sensor inserted into a new shield for continued use of the sensor.