Abstract: Methods and apparatus for assessing the condition of and treating patients for stroke during the delivery of continuous positive airway pressure (CPAP) are disclosed. By determining central and obstructive apnea occurrences or the percentile of pressure delivered to the patient from patient airflow, stroke indicators may be calculated and analyzed to provide information on the type of stroke a patient has suffered and the degree of a patient's neuro-recovery. The apparatus may be programmed with a particular protocol intended to identify between alternative forms of CPAP treatment appropriate for the patient based upon an assessment of the patient's condition. The device can select and recommend between the various treatment forms, identify billing reimbursement codes and generate data to track patient response to stroke treatments.

Abstract: Systems and methods obtain information that allows detection of whether a patient suffers from congestion by monitoring a response of the patient to a recumbent position of the patient's body. The patient may be monitored to determine a respiration pattern for a non-recumbent position such as standing and a respiration pattern for a recumbent position such as lying down. The two patterns may be compared, either by a processing device or a physician, to determine a difference in the two respiration patterns. Furthermore, the congestion may be inferred from detecting an amount of time that the patient spends in a recumbent position of from detecting the recumbent angle that the patient obtains, either of which is presumed to indicate whether a recumbent position presents discomfort to the patient due to the presence of congestion.

Abstract: The invention concerns a device for analysing medical sounds, in particular respiratory sounds, comprising an input receiving a sound signal sampled in intensity levels each associated with a selected time, and storage means (2, 4, 5) comprising a processing module for evaluating, in cooperation with computing means (3), a set of transformed intensity levels, each associated with a predetermined sound frequency. It further comprises an output (26) connected to the storage means (2) for delivering each transformed intensity level in correspondence with an associated frequency, and means for representing (6, 90, 91) intensity levels transformed on the basis of frequencies, to obtain a spectral representation of the auscultation sound.

Abstract: In a respiratory air flow measuring monitor, a subassembly for analyzing certain respiratory gases through infrared spectroscopy includes an infrared emitter and an infrared detector, the amount of energy detected by the detector corresponding to the concentration of the gas selected for analysis. The subassembly includes a gas sample chamber that utilizes an elliptical reflecting surface for the infrared light source. The light source and detector are both oriented longitudinally along the axis of the ellipse and the light source and detector are each located at the two focal points of the ellipse in order to optimize the light absorption reading. The gas content analyzer subassembly additionally incorporates various compensatory features, allowing for automatic temperature and pressure compensation. Specifically, the analyzer includes a continuous air puree feature that inhibits moisture from collecting within the lumen tubes of the analyzer and interfering with the operation of the analyzer.

Abstract: This invention relates to instruments, particularly medical and research instruments that are used for assessing gas volumes of cavities, particularly, cavities that may exhibit a compliance to changes in pressure, such as in vivo volumes of the lung, thorax, oropharynx and/or nasopharynx.

Abstract: An active medical device have an improved diagnosis of a sleep apnea syndrome. This device measures the respiratory activity of the patient, determines a state of activity, this state being likely to take, according to satisfaction of predetermined criteria, a value representative of a state of sleep of the patient, and analyzes a detected signal corresponding to the respiratory activity to detect, when the aforementioned state is a state of sleep, the presence of respiratory pauses, and thereby to produce an indicating signal of sleep apnea in the event of the occurrence of a respiratory pause of duration longer than a first predetermined duration. The analysis also includes inhibiting the production of the aforesaid indicating signal, or a treatment to resolve an apnea, when the duration of the detected respiratory pause is longer than a second predetermined duration, typically of at least one minute.

Abstract: The invention relates to an apparatus for determining the pressure drop over the nose of a patient during breathing and determining the opening pressure for the patients Eustachian tube. The apparatus comprises a measuring tube having a proximal end for connecting to a patients nose and a distal end leading to the surrounding atmosphere, a measuring gate, flow measuring means for measuring air flow in the measuring tube, first pressure measuring means for measuring the pressure in the tube proximal end and second pressure measuring means for measuring the pressure at the measuring gate. According to the invention the apparatus comprises means for generating a sound signal in the tube proximal end, or means for generating a sound signal at the measuring gate and means for receiving sound signals in the tube proximal end. The invention further relates to a method for measuring the above mentioned pressure drop.

Abstract: The adaptive control method for controlling pressure based ventilation utilizes a specific regulator structure designed according to a linear model of the patient/ventilator system. The same model is also used to derive a real time estimate of patient airway resistance, lung compliance, and the connecting tube compliance. These estimates are used to adjust regulator parameters in real time such that closed loop dynamics quickly approach those of a specified system. In the patient/connecting circuit system, G(s) inlet flow and circuit pressure are fed to a parameter estimator, and the output of the parameter estimator is used to adjust the parameters of the compensator, C(s).

Abstract: In a method for assessing pulmonary stress, a flow of respiratory gas is supplied to the lungs of a subject, an ensuing pressure is measured in relation to time and the pressure-time relationship is analyzed. In this analysis, the profile of the pressure-time relationship is determined. In summary, the profile is straight when no stress is present, is convex when there is a risk for over-distension, and is concave when alveolar units are opened up. Implemented in a breathing apparatus the method can be used to assist an operator in diagnostic and therapeutic considerations in relation to a patient.

Abstract: A method and apparatus for monitoring and/or quantitatively measuring a patient's respiration using a flexible piezoelectric film sensor. The apparatus includes a piezoelectric film which converts acoustical waves generated by the patient's respiration into electrical signals. The piezoelectric film sensor can be used to monitor the respiration of a patient by correlating the sound generated in the patient's airway with respiratory activity. Further, the data generated by the sensor may be further analyzed by a patient monitor to diagnose respiratory conditions.

Abstract: The invention refers to a method for the regional determination of the alveolar opening and alveolar closing of the lung depending on the respiration pressure, wherein according to the method of electrical impedance tomography, an impedance signal is measured in at least one lung zone depending on the respiration pressure. The alveolar opening or closing of a lung zone is determined, in particular to enable an improved artificial respiration.

Abstract: In a method for assessing pulmonary stress, a volume of respiratory gas is received from the lungs of a subject, an ensuing pressure is measured and the pressure-volume (P-V) relationship is analyzed. The analysis includes a determination of the profile of the pressure-volume (P-V) relationship. The profile is straight when no stress is present, convex when there is a risk for over-distension and concave when alveolar units are opened up. Implemented in a breathing apparatus the method can be used to assist an operator in diagnostic and therapeutic considerations in relation to a patient.

Abstract: Methods and apparatus for assessing the condition of and treating patients for stroke during the delivery of continuous positive airway pressure (CPAP) are disclosed. By determining central and obstructive apnea occurrences or the percentile of pressure delivered to the patient from patient airflow, stroke indicators may be calculated and analyzed to provide information on the type of stroke a patient has suffered and the degree of a patient's neuro-recovery. The apparatus may be programmed with a particular protocol intended to identify between alternative forms of CPAP treatment appropriate for the patient based upon an assessment of the patient's condition. The device can select and recommend between the various treatment forms, identify billing reimbursement codes and generate data to track patient response to stroke treatments.

Abstract: A device having variable inspiratory resistance suitable for measuring the inspiratory strength of a patient which comprises a chamber in communication with a mouthpiece, said chamber (a) being provided with a calibration system for measuring the inhalation flow rate during inhalation through the mouthpiece and (b) being provided with a variable resistance feature by which the resistance to airflow through the device may be altered.

Abstract: A device having variable inspiratory resistance suitable for measuring the inspiratory strength of a patient which comprises a chamber in communication with a mouthpiece. The chamber is provided with a calibration system for measuring the inhalation flow rate during inhalation through the mouthpiece. The calibration system is also provided with a variable resistance feature where the airflow resistance may be altered.

Abstract: An implantable cardiac device that is adapted to periodically measure a body parameter, such as transthoracic impedance, at time periods selected so that the body parameter is primarily indicative of the respiration of the patient. In this way, a ventilation parameter, such as minute ventilation, can be reconstructed from the signals without requiring filtering of the sampled signals. In one embodiment, the implantable cardiac device measures transthoracic impedance during each quiescent period of the heart and thereby obtains a plurality of transthoracic impedance data points which are then used to reconstruct a ventilation signal. As the transthoracic impedance data points are obtained during the quiescent period, the contribution of the heart to the resulting transthoracic impedance measurement can be ignored and the resulting measurements are indicative of the action of the heart.

Abstract: Apparatus provides an output signal characteristic of the geometry of a confined volume. There is a conduit with an open first end for exchanging acoustical energy with the confined volume. An electroacoustical transducer is coupled to the conduit for launching acoustical energy into the conduit towards the opening in the confined volume producing an incident wave and a reflected wave to form a wave field representative of the geometry of the confined volume. In one embodiment, the acoustical energy is launched into a sidewall of the tube. At least first and second pressure-wave-sensing transducers are mounted along the length of the conduit in spaced relationship for providing first and second transduced signals representative of the wave field at spaced locations in the conduit. A processor processes the first and second transduced signals to provide an output signal characteristic of the geometry of the confined volume. In one embodiment, the processor provides high-pass filtering of the impulse response.

Abstract: In a lung therapy method, hyperpolarized gas is administered for one breath to a subject, and a magnetic resonance scan of at least one lung of the subject is conducted. The data obtained from the scan are evaluated, specifically to determine the extent and distribution of infusion of hyperpolarized gas in the lung, as an indication of the alveolae in the lung which are open. Based on the evaluation of the data obtained in the magnetic resonance scan, a determination is made as to whether administration of a surfactant is necessary in order to improve opening of the lung. If a surfactant is administered, the procedure can be repeated to obtain an updated dataset, which can be evaluated to determine whether the administered surfactant has been effective.

Abstract: In a method for assessing pulmonary stress, a flow of respiratory gas is supplied to the lungs of a subject, an ensuing pressure is measured in relation to time and the pressure-time relationship is analyzed. In this analysis, the profile of the pressure-time relationship is determined. In summary, the profile is straight when no stress is present, is convex when there is a risk for over-distension, and is concave when alveolar units are opened up. Implemented in a breathing apparatus the method can be used to assist an operator in diagnostic and therapeutic considerations in relation to a patient.

Abstract: Apparatus for monitoring oro-nasal respiration. A pair of nasal prongs, suitable for insertion into the lower portion of the nares, join together via a small plenum chamber to form a single tube conveying the nasal pressure towards an electrical pressure transducer. Another prong is held in proximity with the patient's mouth. A baffle element extends downwards from a location above the open end of the prong to redirect a portion of oral airflow. The oral tube extends towards the electrical pressure transducers and conjoins with the nasal tube at a junction to form a common tube connected to the pressure transducer. The relative lengths and/or diameters of the nasal tube and the oral tube are arranged so that the respective pneumatic impedances are different, so that the contributions of respiratory airflow from each of said tubes are substantially equal.

Abstract: A pressurized breathable gas, preferably air, is supplied to the patient's airways with an interface including a mask and a flexible hose. A selected oscillation component or forced probing signal is applied or superposed on the pressurized breathable gas, preferably with a loudspeaker coupled to a frequency generator. Pressure and flow of the breathable gas in the interface are measured or sampled, preferably using pressure transducers and a pneumotachometer coupled to a personal computer, to obtain pressure and flow data characteristic of the patient's airway. The pressure and flow data are converted to the frequency domain using Fourier transform or cross-power spectrum techniques in the personal computer. A function of the processed pressure and flow data is obtained to determine an index of airway impedance or degree of airway obstruction.

Abstract: In a device for acoustic imaging of internal morphology of the respiratory tract which utilizes a hollow acoustic pipe having a speaker on one end and microphones on its side wall the improvement comprising a disposable tube or sleeve which is intended to be coextensive with the pipe, having a filter at its far end and filters to fit over the microphones along with a lip or ring at its outer end so as to avoid cross-contamination between patients whose breath enters the pipe.

Abstract: A method and apparatus is disclosed for determining airway resistance and lung compliance using an electrical circuit model wherein at least one component parameter is non-linear. The system non-intrusively obtains pressure and flow data signals from a pressure transducer and a laminar flow element without interrupting or interfering with normal breathing and gas supply to a patient. An invariant exponential is determined empirically based on physical characteristics of the airway. The non-linear airway resistance and lung compliance can then be calculated based on the sensed flow rate, gas pressure, a calculated gas volume, and the invariant exponential using linear techniques. The resulting airway resistance can be normalized to a standard reporting flow rate value. The system is particularly useful in anesthesia applications, but is also useful in any breathing system where fresh gas is supplied constantly from a gas source other than a ventilator.

Abstract: An airflow perturbation device and system wherein airflow of a subject is alternatingly blocked and unblocked by a mechanism to provide an output of an airflow/differential pressure conversion device based on oscillating differential pressure signals created by the alternating perturbation. The signals are provided by pressure transducers which provide signals to a data acquisition computer which calculates respiratory resistance as an indicator of airway resistance. An airflow perturbation device according to the invention could be a self-contained unit wherein the airflow perturbation mechanism, differential pressure conversion device, transducers, and data acquisition computer are in a single unit. In another embodiment, an airflow perturbation device could include the airflow perturbation mechanism and pressure transducers in a single unit, and provide transducer output to the data acquisition computer for calculation of respiratory resistance.

Abstract: Methods and apparatus for determining the occurrence of an apnea, patency and/or partial obstruction of the airway are disclosed. Respiratory air flow from a patient is measured to give an air flow signal. The determination of an apnea is performed by calculating the variance of the air flow signal over a moving time window and comparing the variance with a threshold value. One determination of partial obstruction of the airway is performed by detecting the inspiratory part of the air flow signal, scaling it to unity duration and area and calculating an index value of the amplitude of the scaled signal over a mid-portion. Alternatively, the index value is a measure of the flatness of the air flow signal over the mid-portion.

Abstract: A cardiorespiratory monitor that generates bioimpedance sensing signals that produce substantially no interference with bioimpedance signals generated by implanted devices. The monitor detects the bioimpedance signal generated by the implanted device, using a voltage detector or a telemetry circuit, for example. The monitor analyzes this detected signal to generate a bioimpedance sensing signal that will not interfere with the sensed signal. For instance, if the monitor produces a pulsed sensing signal, the pulses are delivered in an interval of the detected signal where no pulses are present. Similarly, if the monitor produces a high frequency AC sensing signal, the zero crossings of the AC sensing signal are positioned during the delivery of a pulse by the implanted device.

Abstract: A patient monitoring apparatus for monitoring and/or measuring a physiological characteristic of said patient. A user interface having an interior portion communicates with an airway of a user such that substantially all gas inhaled and exhaled by the user enters the interior portion of the user interface. At least one vent element is associated with the user interface and communicates the interior portion of the user interface with an ambient atmosphere outside the user interface. The vent element and user interface define a flow element across which a pressure differential is created during inhalation and exhalation. The pressure differential is the pressure difference between the pressure within the interior portion of the user interface and the pressure of the ambient atmosphere outside the user interface.

Abstract: The invention concerns a method and apparatus for monitoring respiratory condition by impedance pneumography.An electrical signal is applied at a plurality of frequencies to a human subject by way of a first pair of spaced electrodes applied to the trunk of the body, whilst the resulting electrical signal is monitored at the plurality of frequencies at different points on the body by way of a second pair of spaced electrodes. From the resulting electrical signal a measure of the impedance of a part of the body at the plurality of frequencies is obtained, and a difference signal representing the impedance change with frequency is calculated. The difference signal is normalized with respect to a signal representative of the impedance measure itself at one or more frequencies, thereby suppressing the effect of those impedance signal components--such as movement artifact--whose frequency dependent change is substantially proportional to the impedance signal value.

Abstract: A method of predicting critical points in patient respiration includes monitoring at least one characteristic of a respiratory effort waveform of a patient to detect a respiratory event. A refractory period is defined that includes a hard refractory period during which time the respiratory event cannot be responded to and a soft refractory period following the hard refractory period. The respiratory event outside of the refractory period is detected as a function of a first set of predetermined parameters for the monitored at least one characteristic and the respiratory event within the soft refractory period is detected as a function of a second set of predetermined parameters for the monitored at least one characteristic. The respiratory event may be inspiration onset and the characteristic of the respiratory effort waveform monitored is at least one of slope and amplitude.

Abstract: A process and a device for automatically detecting an abnormal respiratory ound permits a continuous and stress-free registration of abnormal respiratory sounds of a test person under normal life activities over a period of time. The respiratory sounds are detected, processed and evaluated in real time. From the detected frequency range, in the course of the evaluation consideration is given only to the previously determined characteristic frequencies at the position of which in the frequency spectrum of the respiratory sound of the test person an abnormal respiratory sound is to be recognized by a significant feature. The data detected at these frequency positions are compared with data which are individually determined for the test person for fulfillment of specific criteria for the occurrence of an abnormal respiratory sound, and the result of the comparison is made available as a signal.

Abstract: Apparatus provides an output signal characteristic of the geometry of a confined volume. There is a conduit with an open first end for exchanging acoustical energy with the confined volume. An electroacoustical transducer is coupled to the conduit for launching acoustical energy into the conduit towards the opening in the confined volume producing an incident wave and a reflected wave to form a transient wave field representative of the geometry of the confined volume. At least first and second pressure-wave-sensing transducers are mounted along the length of the conduit in spaced relationship for providing first and second transduced signals representative of the transient wave field at spaced locations in the conduit. A processor processes the first and second transduced signals to provide an output signal characteristic of the geometry of the confined volume.

Abstract: A device for measuring the resistance of the respiratory tract with the interrupter method consists essentially of a housing (2) which comprises an air passage (3), and of a closing arrangement (5) for temporarily closing the air passage (3). The closing arrangement (5) may be operated via drive means (8). The drive means (8) are arranged and/or designed such that they can be accelerated in a load-free manner from a rest position (R) into an effectual condition (W). In the effectual condition (W) the drive means (8) engages with the closing arrangement and move the latter from a home position (A) into a closing position (V). With this, it is essential that at the point in time of the coming into engagement of the drive means (8) and the closing arrangement (5), the drive means has a certain energy content.

Abstract: In a device for acoustic imaging of internal morphology of the respiratory tract which utilizes a hollow acoustic pipe having a speaker on one end and microphones on its side wall the improvement comprising a disposable tube or sleeve which is intended to be coextensive with the pipe, having a filter at its far end so as to avoid cross-contamination between patients whose breath enters the pipe while protecting the speaker from humidity.

Abstract: An apparatus and method for using the pressure of the surgical cuff installed surrounding an endotracheal tubes or the flow rate therethrough in the calculation of parameters in lung mechanics.