Abstract: An infant warming apparatus that has a canopy vertically movable with respect to an infant resting on an infant between a lower position wherein the apparatus functions as an incubator and an upper position where the apparatus functions as an infant warmer. A radiant heater is located on the canopy and directs infrared energy in a first path towards the infant platform to warm the infant when the canopy is in the upper position. When the canopy is moved to its lower position to act as an incubator, the infrared energy is redirected along a second path that is directed away from the infant platform so as to prevent residual infrared energy that continues to be emitted even after discontinuing power to the radiant heater from affecting the infant as that radiant heater is moved to a position in close proximity to the infant.

Abstract: A method and apparatus are disclosed for using photoplethysmography to obtain physiological parameter information related to respiration or the autonomic nervous system. In one implementation, the process involves obtaining (602) a pleth, filtering (604) the pleth to remove unwanted components, identifying (606) a signal component of interest based on the filtered signal, monitoring (608) blood pressure changes, monitoring (610) heart rate, and performing (612) an analysis of the blood pressure signal to the heart rate signal to identify a phase relationship associated with the component of interest. Based on this phase relationship, the component of interest may be identified (614) as relating to the respiration or Mayer Wave. If it is related to the respiration wave (616), a respiratory parameter such as breathing rate may be determined (620). Otherwise, a Mayer Wave analysis (618) may be performed to obtain parameter information related to the autonomic nervous system.

Abstract: An infant warming apparatus for supporting an infant upon an infant platform. A radiant heater is located above the infant platform at one end thereof. A canopy covers the infant platform and is movable between a closed position where the infant is enclosed and an open position providing access to the infant and/or the radiant heater can be energized to direct infrared energy toward the infant platform. The canopy is constructed of two sections, one of which is pivotally affixed with respect to the infant platform at or proximate the one end and the other section is movable relative the one section to create an open space so that when the canopy is pivoted to its open position past the radiant heater, the radiant heater is aligned with respect to the open space to allow the radiant energy to reach the infant platform without passing through the canopy.

Abstract: The invention relates to the calibration of a pulse oximeter intended for non-invasively determining the amount of at least two light-absorbing substances in the blood of a subject. In order to bring about a solution by means of which the effects caused by the tissue of the subject can be taken into account in connection with the calibration of a pulse oximeter, initial characterization measurements are carried out for a pulse oximeter calibrated under nominal conditions. Based on the characterization measurements, nominal characteristics are established describing the conditions under which nominal calibration has been defined, and reference data indicating the nominal characteristics are stored. In-vivo measurements are then performed on living tissue and based on the in-vivo measurements and the reference data stored, tissue-induced changes in the nominal characteristics are determined.

Abstract: A calibration system for use with a radiant heater of an infant apparatus such as an infant warmer or an infant incubator. The system includes an electrical circuit that is used to sense the temperature of the infant by means of a thermistor and to provide a digital signal representative of the temperature. An automatic calibration system avoids the use of potentiometers by inputting two known voltages into the circuit by means of a voltage divider and recording the digital output for each voltage input. The two known voltage inputs and the known digital outputs are used in two equations to solve for the span and offset constants in those equations. Once determined, those constants are used to calibrate the system.

Abstract: A pulse oximetry method and system for improved motion correction is disclosed. The method/system provides for the use of a detector output signal to obtain a different plurality of differential absorption data sets in corresponding relation to each of a succession of measurement, wherein each of the data sets includes differential absorption values for light of a first wavelength and light of a second wavelength. The data sets are processed to obtain a relative motion estimate value for each measurement. When the relative motion estimate value for a given measurement falls within a predetermined range (i.e., corresponding with clinical motion), a corresponding blood analyte indicator value is adjusted in a predetermined manner, wherein the corresponding adjusted blood analyte indicator is employable to obtain at least one blood analyte concentration value. In one embodiment, blood analyte indicator values may be readily multiplied by a predetermined adjustment factor (i.e.

Abstract: A remote control and tactile feedback system for a medical apparatus, such as a patient ventilator. The ventilator provides a signal having a property indicative of a desired parameter, such as airway pressure or tidal volume. The system has a member suitable for being received in the hand of a user, such as a clinician. A movable trigger is suitable for being engaged by the fingers of the user. An electrical-mechanical, pneumatic, or hydraulic force applying element is coupled to the trigger for applying a force to the fingers of the user responsive to the parameter signal. A tactile sensation of the desired parameter is thus provided to the user. The trigger is coupled to a signal generator for providing a control signal to the ventilator.

Abstract: A calibration system for use with a radiant heater of an infant apparatus such as an infant warmer or an infant incubator. The system includes an electrical circuit that is used to sense the temperature of the infant by means of a thermistor and to provide a digital signal representative of the temperature. An automatic calibration system avoids the use of potentiometers by inputting two known voltages into the circuit by means of a voltage divider and recording the digital output for each voltage input. The two known voltage inputs and the known digital outputs are used in two equations to solve for the span and offset constants in those equations. Once determined, those constants are used to calibrate the system.

Abstract: An oximeter has an op-amp with a first input, a second input, and an output, the first input being directly connected to a reference voltage. A switch has an input connected to the output of the op-amp, and has a plurality of switch outputs. A transistor has a control input connected to one of the plurality of outputs, and has a current source terminal and a supply terminal. A diode is connected to the current source terminal of the transistor. The supply terminal of the transistor is connected both to the second input of the op-amp and to a second one of the plurality of switch outputs. The switch is thereby in a feedback loop of the op-amp, effecting a feedback-controlled switch for switching the diode on and off.

Abstract: A system for facilitating the delivery of a liquid anesthetic agent from an anesthetic bottle to an anesthetic vaporizer. The system includes a bottle adapter, an anesthetic bottle and a filler arrangement positioned on the anesthetic vaporizer. The bottle adapter and filler arrangement each include a keyed configuration such that only the correct type of anesthetic agent can be emptied into the anesthetic vaporizer. The bottle adapter includes an adapter valve assembly that engages a filler valve assembly contained within the filler. The dimensions and arrangement of the adapter valve assembly and the filler valve assembly insure anesthetic agent is delivered to the anesthetic vaporizer only when the anesthetic agent can safely flow from the anesthetic bottle to the anesthetic vaporizer.

Abstract: A photoplethysmographic instrument is used to obtain physiological parameter information related to low frequency heart rate and blood volume variability. In one implementation, a plethysmographic signal is filtered relative to a Mayer Wave frequency to provide an output related to low frequency blood volume variability. In another implementation, the photoplethysmographic signal is first processed to obtain a heart rate signal and the heart rate signal is in turn processed to obtain information regarding low frequency heart rate variability. In either case, a Mayer Wave effect having potential diagnostic significance can be monitored using a photoplethysmographic instrument such as a pulse oximeter.

Abstract: A filling system for use between an anesthetic storage container and a drug reservoir of an anesthetic vaporizer to prevent overfilling of the drug reservoir. The filling system includes a filling conduit that extends between the drug reservoir and the anesthetic storage container to allow a liquid anesthetic agent to flow from the storage container to the drug reservoir. A closing valve is positioned adjacent to a flow opening of a filling conduit such that the closing valve can be moved to a closed position to prevent the flow of anesthetic agent into the drug reservoir. The closing valve includes a float that controls the opening and closing of the closing valve depending upon the level of the anesthetic agent within the drug reservoir.

Abstract: An oversampling pulse oximeter includes an analog to digital converter with a sampling rate sufficient to take multiple samples per source cycle. In one embodiment, a pulse oximeter (100) includes two mor more light sources (102) driven by light source drives (104) in response to drive signals from a digital signal processing unit (116). The source drives (104) may drive the sources (102) to produce a frequency division multiplex signal. The optical signals transmitted by the light sources (102) are transmitted through a patient's appendage (103) and impinge on a detector (106). The detector (106) provides an analog current signal representative of the received optical signals. An amplifier circuit (110) converts the analog current signal to an analog voltage signal in addition to performing a number of other functions. The amplifier circuit (110) outputs an analog voltage signal which is representative of the optical signals from the sources (102).

Abstract: The invention is directed to a disposable oximetry sensor having an integrally formed connector. In one aspect, the sensor includes a clear flexible substrate on which a light emitter and/or light detector (collectively active component(s)) are mounted to allow those components to emit/detect light though the clear substrate and a second patient-side surface of that substrate. The clear substrate will generally contain one or more electrically conductive traces, preferably formed through a printing process, for interconnection to the active components. In this regard, the clear substrate acts as the electrical connector and lens structure for the active components reducing the overall part count for the sensor's assembly. Additional materials/layers may be added to the sensor including an adhesive layer, a compressible material layer, a light blocking layer, and/or a heat sink for thermal management.

Abstract: A system for facilitating the delivery of a liquid anesthetic agent from an anesthetic bottle to an anesthetic vaporizer. The system includes a bottle adapter, an anesthetic bottle and a filler arrangement positioned on the anesthetic vaporizer. The bottle adapter and filler arrangement each include a keyed configuration such that only the correct type of anesthetic agent can be emptied into the anesthetic vaporizer. The bottle adapter includes an adapter valve assembly that engages a filler valve assembly contained within the filler. The dimensions and arrangement of the adapter valve assembly and the filler valve assembly insure anesthetic agent is delivered to the anesthetic vaporizer only when the anesthetic agent can safely flow from the anesthetic bottle to the anesthetic vaporizer.

Abstract: A method of producing a diode drive current in an oximeter includes sensing at least a part of a current passing through the diode and converting the sensed current to a sensed voltage, inputting the sensed voltage to a feedback amplifier for stabilizing the current passing through the diode, and eliminating an offset voltage across inputs of the feedback amplifier. A pulse oximeter includes a diode for emitting light flashes, a feedback amplifier having inputs, a feedback capacitor, and an output, the feedback amplifier stabilizing a current passing through the diode, a nulling amplifier having inputs, a nulling capacitor, and an output, the nulling amplifier charging and discharging the feedback capacitor until the inputs of the feedback amplifier are at a same voltage. The operation may include synchronizing an elimination of input offset voltages of the feedback and nulling amplifiers with on or off state of diode current.

Abstract: The improved pulse oximeter preprocesses the sets of red and infrared signals received from the probe to remove ambient light, to remove noise, and to de-exponeniate the signals. The linearity of the processed red and infrared signals allows the use of statistical techniques such as linear regression and linear correlation to fit a best fit straight line to the set of pairs of processed red and infrared data points and to measure the goodness of the straight line fit to these data points. The result of this analysis is a linear regression slope and a goodness of fit correlation coefficient. The correlation coefficient is a measure of the linearity of the input data points and, if less than a predetermined threshold, it indicates that a distorted signal has been received from the probe. This permits the pulse oximeter to detect probe off conditions and/or motion in the patient.

Abstract: An apparatus and method for monitoring a secondary physiological process through variations caused by the secondary process in an optical signal used to calculate values related to blood oxygen levels. In particular, the optical signal may be divided into distinct portions such that a portion more directly affected by a particular secondary physiological process may be isolated and the secondary physiological process monitored. The apparatus and method is particularly useful for photoplethysmographically monitoring a patient's respiration frequency through changes in relative concentrations of blood oxygen related values that are proportionally related to the amounts of venous and arterial blood in a portion of tissue.

Abstract: An oximeter diode-driving device has a diode, a transistor operative to controllably connect current to the diode, a current sensing resistor that senses at least part of the current, a feedback amplifier operative to control the connecting of current by the transistor according to the current sensed by the current sensing resistor, and an inductor disposed in series with the current sensing resistor. A method of driving a current through the diode of an oximeter includes driving a current through the diode by connecting the current to the diode, controlling the connecting using a feedback type amplifier, the feedback type amplifier having a current source that uses a current-limiting resistor, and adding phase lead to a current passing through the current-limiting resistor.

Abstract: A pleth signal is analyzed to identify a heart rate variability parameter associated with respiration rate. In one embodiment, an associated process involves obtaining a photoplethysmograpic signal, processing the pleth signal to obtain heart rate samples, monitoring the heart rate sample to identify a heart rate variability associated with respiration, and determining a respiration rate based on the heart rate variability. The photoplethysmographic signal may be based on one or more channel signals of a conventional pulse oximeter. The invention thus allows for noninvasive monitoring of respiration rate and expands the functionality of pulse oximeters.