Ventilatory assistance for treatment of cardiac failure and Cheyne-Stokes breathing
First Claim
1. A method for treatment of Cheyne-Stokes breathing during the provision of ventilatory support comprising the steps of:
- delivering a controlled supply of breathable gas at a pressure above atmospheric to a subject to provide the subject with ventilatory support during an inspiratory portion and an expiratory portion of a respiratory cycle of the subject;
deriving a measure of respiratory airflow from the subject;
selecting a ventilatory support target measure to oppose a Cheyne-Stokes pattern of breathing, said ventilatory support target measure being determined as a function of the measure of respiratory airflow; and
modulating the degree of ventilatory support as a function of said ventilatory support target measure and said measure of respiratory airflow,wherein said ventilatory support counteracts a Cheyne Stokes waxing-waning pattern of breathing by changing pressure levels in the inspiratory portion and the expiratory portion, said changing pressure levels varying from previous pressure levels delivered in a previous inspiratory portion and a previous expiratory portion of a previous respiratory cycle of the subject.
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Accused Products
Abstract
Method and apparatus for the treatment of cardiac failure, Cheyne Stokes breathing or central sleep apnea are disclosed. A subject is provided with ventilatory support, for example positive pressure ventilatory support using a blower and mask. Respiratory airflow is determined. From the respiratory airflow are derived a measure of instantaneous ventilation (for example half the absolute value of the respiratory airflow) and a measure of longterm average ventilation (for example the instantaneous ventilation low pass filtered with a 100 second time constant). A target ventilation is taken as 95% of the longterm average ventilation. The instantaneous ventilation is fed as the input signal to a clipped integral controller, with the target ventilation as the reference signal. The output of the controller determines the degree of ventilatory support. Clipping is typically to between half and double the degree of support that would do all the respiratory work. A third measure of ventilation, for example instantaneous ventilation low pass filtered with a time constant of 5 seconds, is calculated. Ventilatory support is in phase with the subject'"'"'s respiratory airflow to the fuzzy extent that this ventilation is above target, and at a preset rate conversely.
104 Citations
22 Claims
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1. A method for treatment of Cheyne-Stokes breathing during the provision of ventilatory support comprising the steps of:
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delivering a controlled supply of breathable gas at a pressure above atmospheric to a subject to provide the subject with ventilatory support during an inspiratory portion and an expiratory portion of a respiratory cycle of the subject; deriving a measure of respiratory airflow from the subject; selecting a ventilatory support target measure to oppose a Cheyne-Stokes pattern of breathing, said ventilatory support target measure being determined as a function of the measure of respiratory airflow; and modulating the degree of ventilatory support as a function of said ventilatory support target measure and said measure of respiratory airflow, wherein said ventilatory support counteracts a Cheyne Stokes waxing-waning pattern of breathing by changing pressure levels in the inspiratory portion and the expiratory portion, said changing pressure levels varying from previous pressure levels delivered in a previous inspiratory portion and a previous expiratory portion of a previous respiratory cycle of the subject. - View Dependent Claims (2, 3, 4, 5)
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6. An apparatus for the treatment of Cheyne-Stokes breathing comprising:
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means for providing a breathable gas at a controllable pressure above atmospheric to a subject; means for deriving a flow signal indicative of a measure of respiratory airflow of the subject; and a controller to run said means for providing a breathable gas in response to said flow signal, wherein said controller comprises programmed instructions for execution by said controller, said instructions controlling steps of; delivering ventilatory support during an inspiratory portion and an expiratory portion of a respiratory cycle to the subject; determining a ventilatory support target measure as a function of the flow signal, said ventilatory support target measure being selected to oppose a Cheyne-Stokes pattern of breathing; and modulating the degree of ventilatory support to counteract a Cheyne-Stokes waxing-waning pattern of breathing by changing pressure levels in the inspiratory portion and the expiratory portion, said changing pressure levels varying from previous pressure levels delivered in a previous inspiratory portion and a previous expiratory portion of a previous respiratory cycle of the subject. - View Dependent Claims (7, 8, 9, 10)
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11. A method for treatment of Cheyne-Stokes breathing during the provision of ventilatory support comprising the steps of:
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delivering a controlled supply of breathable gas at a pressure above atmospheric to a subject; deriving a measure of respiratory airflow from the subject; selecting a ventilatory support target measure to oppose a Cheyne-Stokes pattern of breathing, said ventilatory support target measure being determined as a function of the measure of respiratory airflow; and deriving an input value from said measure of respiratory airflow, said input value being derived during a time period less than that of one breath; and changing the degree of ventilatory support provided by said delivering step to counteract a Cheyne-Stokes waxing-waning pattern of breathing as a function of said ventilatory support target measure and said input value. - View Dependent Claims (12, 13, 14, 15, 16)
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17. Apparatus for the treatment of Cheyne-Stokes breathing comprising:
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means for providing a breathable gas at a controllable pressure above atmospheric to a subject; means for deriving a flow signal indicative of a measure of respiratory airflow of the subject; and a controller to operate said means for providing a breathable gas in response to said flow signal, wherein said controller comprises programmed instructions for execution by said controller, said instructions controlling the steps of; delivering a controlled supply of breathable gas at a pressure above atmospheric to the subject; calculating a ventilatory support target measure as a function of the flow signal to oppose a Cheyne-Stokes pattern of breathing; calculating an input value from said flow signal, said input value being derive during a time period less than that of one breath; and adjusting the degree of ventilatory support provided by said delivering step to counteract a Cheyne-Stokes waxing-waning pattern of breathing as a function of said ventilatory support target measure and said input value. - View Dependent Claims (18, 19, 20, 21, 22)
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Specification