Ventilatory assistance for treatment of cardiac failure and Cheyne-stokes breathing

A method for treatment of cardiac failure, Cheyne-Stokes breathing or central sleep apnea, comprising the steps of:

• providing a subject with ventilatory support;
• deriving a measure of the subject's instantaneous ventilation;
• deriving a measure of the subject's longterm average ventilation;
• setting the controlled variable of a servo-controller to a function of said measure of the subject's longterm average ventilation;
• and
• setting the reference variable of said servo-controller to a measure of the subject's longterm average ventilation;
• and
• adjusting the magnitude of said ventilatory support in accordance with the output of said servo-controller.

A method for treatment of cardiac failure, Cheyne-Stokes breathing or central sleep apnea, comprising the steps of:

• providing a subject with ventilatory support;
• deriving a measure of the subject's instantaneous ventilation;
• high pass filtering said measure of the subject's instantaneous ventilation;
• and
• adjusting the degree of said ventilatory support inversely with said high pass filtered measure of the subject's instantaneous ventilation.

Apparatus for the treatment of cardiac failure, Cheyne-Stokes breathing or central sleep apnea, comprising:

• a device for providing ventilatory support of controllable magnitude;
• means for deriving a signal indicative of instantaneous ventilation of a subject;
• and
• a servo-controller operable to control the degree of ventilatory support provided by said ventilatory support device to oppose short-term changes in said measure of instantaneous ventilation, but permit longterm changes in said measure of instantaneous ventilation.

Apparatus for treatment of cardiac failure, Cheyne-Stokes breathing or central sleep apnea, comprising:

• a controllable source of breathable gas at positive pressure;
• means for delivering said breathable gas at positive pressure to a subject's airway;
• means for deriving a measure of the subject's instantaneous ventilation;
• and
• a servo-controller for adjusting the degree of ventilatory support to reduce changes in said measure of instantaneous ventilation over a timescale similar to that of the waxing-waning cycle of untreated Cheyne-Stokes breathing or central sleep apnea, while allowing changes in said measure of instantaneous ventilation over a timescale much longer than said waxing-waning cycle.

Apparatus for treatment of cardiac failure, Cheyne-Stokes breathing or central sleep apnea, comprising:

• a controllable source of breathable gas at positive pressure;
• means for delivering said breathable gas at positive pressure to a subject's airway;
• means for deriving a measure of the subject's instantaneous ventilation;
• means for deriving a measure of the subject's longterm average ventilation;
• means for deriving a target ventilation as a function of said measure of the subject's longterm average ventilation;
• a servo-controller whose input variable is a function of said measure of the subject's instantaneous ventilation, and whose reference variable is said target ventilation;
• and
• means for adjusting the magnitude of said ventilatory support according to the output of the servo-controller.

Apparatus for treatment of cardiac failure, Cheyne-Stokes breathing or central sleep apnea, comprising:

• a controllable source of breathable gas at positive pressure;
• means for delivering said breathable gas at positive pressure to a subject's airway;
• means for deriving a measure of the subject's instantaneous ventilation;
• means for high pass filtering said measure of the subject's instantaneous ventilation;
• and
• a servo-controller whose input variable is a function of said 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.

A method for the treatment of cardiac failure, Cheyne-Stokes breathing or central sleep apnea, comprising the steps of:

• providing a subject with positive pressure ventilatory support, with controllable amplitude and rate;
• deriving a measure of the subject's instantaneous ventilation;
• adjusting said amplitude of positive pressure by:
• (a) low pass filtering said measure of instantaneous ventilation to derive a measure of recent average ventilation;
• (b) setting a target ventilation equal to a fraction of said measure of recent average ventilation;
• and
• (c) servo-controlling said measure of instantaneous ventilation to at least equal the target ventilation, by adjusting the degree of ventilatory support;
• and
• continuously adjusting said rate by:
• (a) to the extent that the instantaneous ventilation equals or exceeds said target ventilation, modulating said positive pressure in phase with respiratory airflow;
• and p2 (b) to the extent that the instantaneous ventilation is less than said target ventilation, modulating said positive pressure at a preset rate.

Apparatus for the treatment of cardiac failure, Cheyne-Stokes breathing or central sleep apnea, comprising:

• ventilator means for providing ventilatory support with controllable amplitude and rate;
• sensor and processing means for deriving a signal indicative of instantaneous ventilation of a subject;
• and
• servo-control means operable to adjust the amplitude of the pressure support by low pass filtering said instantaneous ventilation signal to derive a measure of recent average ventilation, setting a target ventilation equal to a fraction of said measure of recent average ventilation, and servo-controlling said measure of instantaneous ventilation to at least equal the target ventilation, and further operable to continuously adjust said rate by modulating said positive pressure in phase with respiratory airflow to the extent that the instantaneous ventilation equals or exceeds said target ventilation, and modulating said positive pressure at a pre-set rate to the extent that the instantaneous ventilation is less than said target ventilation.

A method for treatment of cardiac failure, Cheyne Stokes breathing or central sleep apnea, comprising the steps of:

• providing a subject with ventilatory support;
• deriving a measure of instantaneous ventilation;
• and
• adjusting the degree of ventilatory support to oppose short term changes in said measure of instantaneous ventilation, but permitting longterm changes in said measure of instantaneous ventilation.