Ventilatory assistance for treatment of cardiac failure and cheyne-stokes breathing
First Claim
1. Apparatus for treatment of cardiac failure, Cheyne-Stokes breathing or central sleep apnea, comprising:
- a controllable source of breathable gas at positive pressure;
a conduit for delivering said breathable gas at positive pressure to a subject'"'"'s airway to provide ventilatory support;
a processor controlled by software for deriving a measure of the subject'"'"'s instantaneous ventilation;
a high pass filter for the measure of the subject'"'"'s instantaneous ventilation; and
a servo-controller whose input variable is a function of the high pass filtered measure of the subject'"'"'s instantaneous ventilation, and which adjusts the magnitude of said ventilatory support inversely with said high pass filtered measure of the subject'"'"'s instantaneous ventilation.
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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.
33 Citations
11 Claims
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1. Apparatus for treatment of cardiac failure, Cheyne-Stokes breathing or central sleep apnea, comprising:
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a controllable source of breathable gas at positive pressure; a conduit for delivering said breathable gas at positive pressure to a subject'"'"'s airway to provide ventilatory support; a processor controlled by software for deriving a measure of the subject'"'"'s instantaneous ventilation; a high pass filter for the measure of the subject'"'"'s instantaneous ventilation; and a servo-controller whose input variable is a function of the high pass filtered measure of the subject'"'"'s instantaneous ventilation, and which adjusts the magnitude of said ventilatory support inversely with said high pass filtered measure of the subject'"'"'s instantaneous ventilation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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Specification