Abstract: The present invention relates to a method and device for determining a level of ventilatory assist to a ventilator-dependent patient, in which a critical threshold of a respiration-related feature is calculated. Fatigue of a respiratory muscle of the ventilator-dependent patient develops when the critical threshold is reached by the respiration-related feature. The level of ventilatory assist to the ventilator-dependent patient is controlled in relation to the critical threshold of the respiration-related feature so as to prevent fatigue of the patient's respiratory muscle.

Abstract: The present invention relates to a method of delivering combined positive and negative pressure assist ventilation to a patient, wherein a positive pressure is applied to the patient's airways to inflate the patient's lungs, a negative pressure is applied around the patient's ribcage and/or abdomen in order to reduce a load imposed by the ribcage and/or abdomen on the patient's lungs, and application of the positive and negative pressures is synchronized.

Abstract: Described is an electrode array for measuring electrical activity in a subject's biological tissue, comprising an electrode support, a group of electrodes mounted on the electrode support, and an inter-electrode conductive medium having a given resistivity for controlling resistivity between the electrodes of the group. Also, described is a method for controlling the inter-electrode resistivity in the electrode array comprises providing the inter-electrode conductive medium having the given resistivity between the electrodes of the group, and interconnecting the electrodes of the group through this inter-electrode conductive medium to control resistivity between the electrodes.

Abstract: A closed loop system uses (a) the intensity of the diaphragm electromyogram (EMG) for a given inspiratory volume; (b) the inspiratory volume for a given EMG intensity; or (c) a combination of (a) and (b); in view of controlling the level of gas flow, gas volume or gas pressure delivered by a mechanical (lung) ventilator. The closed loop ventilator system enables for automatic or manual adjustment of the level of inspiratory support in proportion to changes in the neuro-ventilatory efficiency such that the neural drive remains stable at a desired target level. An alarm can also be used to detect changes in neuroventilatory efficiency in view of performing manual adjustments.

Abstract: A gain controller and method for controlling the value of a gain is used in conjunction with an electrode array for detecting a signal representative of respiratory drive output of a patient during inspiration, and a lung ventilator for assisting inspiration of the patient. The gain controller comprises an input for receiving the signal representative of respiratory drive output; a comparator for determining whether the signal representative of respiratory drive output is higher or lower than a target drive signal; and a gain adjustment unit for increasing the value of a gain when the amplitude of the signal representative of respiratory drive output is higher than the amplitude of the target drive signal and for decreasing the value of this gain when the amplitude of the signal representative of respiratory drive output is lower than the amplitude of the target drive signal.

Abstract: A gain controller and method for controlling the value of a gain is used in conjunction with an electrode array for detecting a signal representative of respiratory drive output of a patient during inspiration, and a lung ventilator for assisting inspiration of the patient. The gain controller comprises an input for receiving the signal representative of respiratory drive output; a comparator for determining whether the signal representative of respiratory drive output is higher or lower than a target drive signal; and a gain adjustment unit for increasing the value of a gain when the amplitude of the signal representative of respiratory drive output is higher than the amplitude of the target drive signal and for decreasing the value of this gain when the amplitude of the signal representative of respiratory drive output is lower than the amplitude of the target drive signal.

Abstract: A method and device for controlling positive pressure assist to a patient during expiration, measure a level of electrical activity of a patient's respiration-related muscle during expiration. In response to the measured level of electrical activity, a level of positive pressure assist to the patient during expiration is adjusted in view of minimizing the level of electrical activity of the patient's respiration-related muscle during expiration.

Abstract: A closed loop system uses (a) the intensity of the diaphragm electromyogram (EMG) for a given inspiratory volume; (b) the inspiratory volume for a given EMG intensity; or (c) a combination of (a) and (b); in view of controlling the level of gas flow, gas volume or gas pressure delivered by a mechanical (lung) ventilator. The closed loop ventilator system enables for automatic or manual adjustment of the level of inspiratory support in proportion to changes in the neuro-ventilatory efficiency such that the neural drive remains stable at a desired target level. An alarm can also be used to detect changes in neuroventilatory efficiency in view of performing manual adjustments.

Abstract: A method and system for producing higher quality electromyogram (EMG) signals utilizes an array of electrodes for sensing a plurality of EMG signals in an electrically active region of a subject's muscle. A weighting function is applied to the EMG signals to produce weighted signals. This weighting function contains correction features for the relative locations of the center of the electrically active region and the electrodes. The quality of the weighted EMG signals is evaluated, and the weighted signals or sum or mean of the weighted signals whose evaluated quality is insufficient are replaced. A sum or mean of a feature of the weighted signals is calculated to produce a higher quality electromyocardiographic signal. The method and system can also be used to determine signal strength or frequency contents of a signal falling outside the array of electrodes.

Abstract: The method and system are for sealing/unsealing (regulating) airway leaks occuring between the ventilator circuit and respiratory airways during lung ventilatory support in response to myoelectrical activity of diaphgram. Myolectrical activity of a patient's respiratory-related muscle is sensed to detect respiratory effort, and to produce a myoelectrical signal representative of the sensed muscle myoelectrical activity. Respiratory flow and pressure can also be measured to produce respective respiratory pressure and respiratory flow signals. A logic trigger sealing/unsealing of airway leaks in relation to the myoelectrical signal, respiratory flow signal and/or respiratory pressure signal to assist respiration of the patient. The amplitude of the myoelectrical signal Is compare to a given threshold, and airway leaks are sealed when the amplitude of the myoelectrical signal is higher than this threshold.

Abstract: Described is an electrode array for measuring electrical activity in a subject's biological tissue, comprising an electrode support, a group of electrodes mounted on the electrode support, and an inter-electrode conductive medium having a given resistivity for controlling resistivity between the electrodes of the group. Also, described is a method for controlling the inter-electrode resistivity in the electrode array comprises providing the inter-electrode conductive medium having the given resistivity between the electrodes of the group, and interconnecting the electrodes of the group through this inter-electrode conductive medium to control resistivity between the electrodes.

Abstract: A closed loop system uses (a) the intensity of the diaphragm electromyogram (EMG) for a given inspiratory volume; (b) the inspiratory volume for a given EMG intensity; or (c) a combination of (a) and (b); in view of controlling the level of gas flow, gas volume or gas pressure delivered by a mechanical (lung) ventilator. The closed loop ventilator system enables for automatic or manual adjustment of the level of inspiratory support in proportion to changes in the neuro-ventilatory efficiency such that the neural drive remains stable at a desired target level. An alarm can also be used to detect changes in neuroventilatory efficiency in view of performing manual adjustments.

Abstract: A closed loop system uses (a) the intensity of the diaphragm electromyogram (EMG) for a given inspiratory volume; (b) the inspiratory volume for a given EMG intensity; or (c) a combination of (a) and (b); in view of controlling the level of gas flow, gas volume or gas pressure delivered by a mechanical (lung) ventilator. The closed loop ventilator system enables for automatic or manual adjustment of the level of inspiratory support in proportion to changes in the neuro-ventilatory efficiency such that the neural drive remains stable at a desired target level. An alarm can also be used to detect changes in neuroventilatory efficiency in view of performing manual adjustments.

Abstract: A method and device for triggering ventilatory support to assist the patient's respiration. Myoelectrical activity of a patient's respiratory-related muscle is sensed to detect respiratory effort, and to produce a myoelectrical signal representative of the sensed muscle myoelectrical activity. Respiratory flow and pressure can also be measured to produce respective respiratory pressure and respiratory flow signals. A logic trigger circuit triggers ventilatory support in relation to the myoelectrical signal, respiratory flow signal and/or respiratory pressure signal to assist respiration of the patient. The amplitude of the myolectrical signal is compared to a given threshold, and ventilatory support is triggered when the amplitude of the myoelectrical signal is higher than this threshold.

Abstract: A myographic probe for detecting an electrical signal produced by a muscle and for reducing the influence of electrode disturbances. The probe includes electrodes and a disturbance reducing interface covering each electrode thereby segragating the electrodes from the muscle. Electrode disturbances include problems such as those related to the motion of the electrodes, changes in the pressure applied to the electrode, and/or intermittent contact with sourrounding tissue. The disturbance reducing interface is ion permeable and is, when dry, less conductive than the electrodes. The disturbance reducing interface may comprise a matrix of permeable material such as a mesh, foam, or other porous materials. The probe may be in the form of a catheter and be advantageously used in a human cavity such as the oesophagus. Another advantage of the invention is the possibility of using electrodes which are different from conventional wound wire electrodes.

Abstract: To control a lung ventilator comprising an inspiratory implement to be worn by the patient, an air supply system for supplying air to the inspiratory implement, and a control unit for controlling the air supply system, electromyographic signals produced by the patient's diaphragm are detected by an array of electrodes passing through the center of the patient's diaphragm depolarizing region. The position of the center of the patient's diaphragm depolarizing region is determined through detection of a reversal of polarity of the electromyographic component of the electrode-detected electromyographic signals.

Abstract: In the method and system for electromyographic analysis of a striated muscle, electromyographic signals produced by the muscle are detected by means of an array of electrodes passing through the center of the muscle depolarizing region. Each electromyographic signal comprises an electromyographic component and a noise component. The position of the center of the muscle depolarizing region is then determined by detecting a reversal of polarity of the electromyographic components of the signals. Finally, two signals of opposite polarities amongst the electromyographic signals are subtracted. The subtraction subtracts the noise components of the two signals from each other but adds the electromyographic components of the two signals together to produce an electromyographic signal of improved signal-to-noise ratio.