58 results about "End tidal" patented technology

Techniques are provided for detecting the circadian state of a patient using an implantable medical device based on selected blood carbon dioxide (CO₂) parameters. In one example, the implantable device tracks changes in end tidal CO₂ (etCO₂) levels and changes in maximum variations of pCO₂ levels per breathing cycle (Δ_cycleCO₂) over the course of the day and determines the circadian state based thereon. It has been found that average etCO₂ levels are generally highest and average Δ_cycleCO₂ levels are generally lowest while a patient is asleep and opposite while a patient is awake. Hence, by tracking changes in average etCO₂ and Δ_cycleCO₂ levels over the course of the day, circadian states can be detected. Minute ventilation and activity levels are used to assist in the determination of the circadian state. Additional techniques are directed to detecting the stage of sleep.

A noninvasive apparatus and method for measuring a subject's end tidal carbon monoxide concentration is disclosed, featuring the ability to (i) determine carbon monoxide concentration on a breath-by-breath basis, (ii) determine mean carbon monoxide concentration by averaging local carbon monoxide values, (iii) avoid the premature determination that an end tidal phase is over, and (iv) determine when breath variability or system variability will likely preclude accurate testing. The disclosed device and method allow for more robust determination of end tidal carbon monoxide concentration in subjects with turbulent or irregular breath patterns.

A non-invasive monitoring apparatus for end-tidal gas concentrations, and a method of use thereof, is described for the detection of endogenous gas concentrations, including respiratory gases, in exhaled breath.

In a first aspect, the invention relates to an apparatus for inducing or maintaining a target end tidal concentration of a gas in a subject comprising a breathing circuit, a source of gas flow into the circuit, means for controlling the rate of the source of gas flow into the circuit and means for controlling the concentration of gases in the source gas flow independently from each other. In another aspect, the invention relates to a method of preparing an apparatus for inducing or maintaining a target end tidal concentration of a gas X in a subject comprising selecting a rate of a source gas flow into a breathing circuit, selecting the concentration of at least one constituent gas of a component gas making up the source gas to a level corresponding to the end tidal concentration of the gas X, whereby the apparatus is adapted to administer a source gas having a first gas composition

An oropharyngeal device for insertion into the mouth of a patient. The device includes a body having a distal end and a proximal end with a flange formed at the proximal end. The distal end is inserted into the mouth until the flange is disposed outside and adjacent to the patient's mouth. The flange keeps the proximal device from entering the mouth. The body is sized such that the distal end of the body is disposed within the pharynx above the epiglottis. The device includes a channel that forms an airway between the ends. The device also includes at least three separate conduits integrated into the body for administering oxygen, suctioning, and for assessing ventilation thorough end-tidal carbon dioxide monitoring. The conduits for oxygenation and suctioning extend through the body between its proximal and distal ends. The conduit for end-tidal carbon dioxide monitoring terminates within the channel.

A method and apparatus for determining the presence or absence of a pulmonary embolism (PE) in a patient. The breathing gas CO₂ partial pressure (PCO₂) during the expiration of breathing gases by the patient, the end tidal (EtCO₂), CO₂ partial pressure, and the CO₂ partial pressure (PaCO₂) of the blood are measured. The volume (V) of breathing gases expired during the expiration of breathing gases by the patient is also measured and a relationship between changes in breathing gas CO₂ partial pressure (PCO₂) and changes in breathing gas volume (V) in an alveolar expiration phase of patient expiration is determined. The difference between the blood CO₂ partial pressure (PaCO₂) and the end expiration CO₂ partial pressure is divided by the relationship between PCO₂ and V produce a quantity which is compared to a threshold value. If the quantity is below the threshold value, the absence of a pulmonary embolism is indicated.

Apparatus and methods for non-invasively determining cardiac output using partial re-breathing techniques are disclosed in which the apparatus is constructed with an instantaneously adjustable deadspace for accommodating differences in breathing capacities of various patients. The apparatus is constructed of inexpensive elements, including a single two-way valve which renders the apparatus very simple to use and inexpensive so that the unit may be readily disposable. The method of the invention provides a novel means of estimating cardiac output based on alveolar CO₂ values rather than end-tidal CO₂ values as previously practiced. A program for calculating cardiac output is also disclosed.

A method and apparatus for determining a user's Respiratory Quotient (RQ) using just measured O₂ and CO₂ concentrations without use of a flow meter. The RQ is determined by measuring the user's real-time inspired O₂ concentration (INS O2) and end tidal O₂ concentration (ETO2) and measuring the user's real-time inspired CO₂ concentration (INS CO2) and end tidal CO₂ concentration (ETCO2), and then determining the user's RQ from the measured INS O2, ETO2, INS CO2, and ETCO2 values in accordance with the following equation: RQ=(ETCO2−INS CO2)/(INS O2−ETO2). In order to avoid error introduced by the flow rate, the measurement steps are preferably performed while the user is in a resting condition. Also, ETCO2 is preferably measured as the maximum CO₂ value in a breath cycle of the user, while INS CO2 is preferably measured as the minimum CO₂ value in a breath cycle of the user. Similarly, ETO2 is preferably measured as the minimum O₂ value within a breath cycle of the user, while INS O2 is measured as the maximum O₂ value within a breath cycle of the user. On the other hand, the values of INS CO2 and ETCO2 also may be determined in accordance with the invention by analysis of a CO₂ waveform of a breath cycle of the user and the values of INS O2 and ETO2 determined by synchronizing timing of the O₂ waveform of a breath cycle of the user with the CO₂ waveform and sampling INS O2 and ETO2 values simultaneously with sampling of complementary CO₂ values determined by analysis of the CO₂ wavefomm. The RQ measuring device may include the oxygen and CO₂ sensors in a mainstream or sidestream configuration.

A sensor adaptor (20) couples a face mask (22) to a gas sampling tube (24) connected to a device detecting end-tidal carbon dioxide. The sensor adaptor (20) includes a shaft (30) and connector (54). The shaft (30) includes a channel (40) providing a pathway for the carbon dioxide to travel toward the gas sampling tube (24). One end of the shaft (30) includes an adaptor tip (26) which extends through an exit port (28) of the face mask (22). A connector (54) is attached to the other end of the shaft (30) and couples the sensor adaptor (20) to the gas sampling line. A gripper (42) may surround the shaft (30) and prevent improper advancement of the shaft (30) into the face mask (22). The sensor adaptor (20) can be designed for use with any gas sampling tube and any face mask including exit ports.

A system for controlling an amount of at least one gas X in a subject's lung to target at least one end tidal partial pressure of at least one gas X (PetX^T) uses a control system for controlling the gas delivery device, wherein the control system implements a sequential gas delivery system and a feedback algorithm which compares a PetX^T for a respective breath of variable size and preferably a respective current PetX value measured by a measurement system, to obtain an error signal, the feedback algorithm adapted for generating a control signal based on the error signal, the control signal determining the amount of gas X to be inspired by the subject in at least a first portion of a respective ensuing respective inspiratory cycle to target PetX^T for the respective interval.

A method of setting expiratory time in controlled mechanical ventilation varies a subject's expiratory times; determines end tidal gas concentrations associated with the expiratory times; establishes a stable condition of the gas concentrations; and determines an optimal expiratory time based on a deviation from the stable condition. A device for use in controlled mechanical ventilation comprises means for the same.

A method for non-invasively determining functional cardiac output (FCO) and/or venous blood CO₂ partial pressure (PvCO₂). The amount of CO₂ (VCO₂^N) released from the blood and end capillary blood CO₂ content (CcCO₂^N) are determined from measurements from exhaled breathing gases. The CO₂ content of the breathing gases inhaled by the subject is increased and values for VCO₂^R and CcCO₂^R are obtained. A regression analysis is performed using the obtained VCO₂^N, VO₂^R, CcCO₂^N, and CcCO₂^R values. The regression line is extrapolated to obtain a value for CcCO₂ when (VCO₂) is zero so that CvCO₂ becomes known. The CvCO₂ thus determined can be inserted in a non-differential form in the Fick equation, along with VCO₂ and CcCO₂ values from normal breathing, to determine FCO. To determine PvCO₂, CvCO₂ is altered in accordance with the amount of oxygen in the venous blood, to correctly indicate PvCO₂. The continuing validity of the FCO measurement can be examined on a breath-by-breath basis by noting changes in an indicator variable, such as VCO₂ or end tidal CO₂ amounts.

An air mixing chamber is herein provided. More particularly, the air mixing chamber mixes the end-tidal and dead space air of exhaled breath for purposes of analysis using baffles with holes that direct the flow of the exhaled breath. The baffles are enclosed inside an enclosure that includes an inlet tube, an outlet tube and a sensor.

An apparatus and method for controlling the end tidal partial pressure of a gas X in a subject's lung, and to the use of such an apparatus and method for research, diagnostic and therapeutic purposes, wherein the method consists of: obtaining input of a series of logistically attainable PetX values for a series of respective breaths: determining an amount of gas X required to be inspired by the subject in an inspired gas to target the PetX for each of said respective breaths: and controlling a gas delivery device to deliver the amount of gas in a volume of gas delivered to the subject in each of said respective breaths to target the respective PetX for that breath.

A method and apparatus for the non-evasive determination of the cardiac output of a subject by causing the subject to inhale and exhale air via a respiratory tube in a plurality of breathing cycles including normal breathing cycles in which the inhaled air does not receive any significant amount of exhaled air from the preceding cycle, and rebreathing cycles in which the inhaled air receives an end tidal portion of the exhaled air from the preceding cycle, propagating ultrasonic pulses through the air passing through the respiratory tube and computing the flow volume through the tube from the measured transit times of the pulses and determining the carbon dioxide content in the exhaled air during both the normal breathing cycles and the rebreathing cycles to determine the cardiac output of the subject.

The invention discloses a monitoring method and a device for partial pressure of carbon dioxide. The monitoring method for partial pressure of carbon dioxide comprises the steps: acquiring arterial carbon dioxide pressure PaCO2 and end-tidal carbon dioxide pressure EtCO2; and determining the estimated value of arterial carbon dioxide pressure PaCO2' at the measurement time according to the arterial carbon dioxide pressure PaCO2 and end-tidal carbon dioxide pressure EtCO2. According to the invention, the number of invasive measurement to a human body is reduced, the pain of a person to be measured is alleviated, the monitoring of partial pressure of carbon dioxide is more safe, the estimated value of corresponding arterial carbon dioxide pressure can be quickly obtained by the end-tidal carbon dioxide pressure EtCO2, the blood and vigor status of the human body is dynamically reflected in real time, and the monitoring of the arterial carbon dioxide pressure is quicker and more visual.