Methods and apparatus for heart failure treatment

Abstract

Methods and apparatus for assessing the condition of and treating patients for heart failure by the delivery of continuous positive airway pressure are disclosed. Airflow of the patient is measured to determine occurrences of central apneas. A heart failure index is calculated from a count of the number of central apneas that have occurred. The present heart failure index can be compared with a previously calculated heart failure index to determine how the patient's heart failure disease has changed and how it should be treated.

Description

[0001] This application claims the benefit of and is a continuation-in-part of PCT / AU2004 / 001420 filed on Oct. 15, 2004. Such PCT application as well as this continuation-in-part claim the benefit of U.S. provisional application Ser. No. 60 / 512,553 filed on Oct. 17, 2003. This continuation-in-part also claims the benefit of U.S. provisional application Ser. No. 60 / 638,169 filed on Dec. 23, 2004.FIELD OF THE INVENTION [0002] The invention relates to methods and apparatus for diagnosing, managing and treating congestive heart failure. BACKGROUND OF THE INVENTION [0003] It has been estimated that in the United States alone that almost five million people suffer from congestive heart failure. Statistics from the American Heart Association also suggest that new cases of heart failure are diagnosed at a rate of about 500,000 each year. Of the newly diagnosed patients fifty percent are likely to die within five years from the initial diagnosis. Of course, these numbers do not account for t...

AI Technical Summary

Benefits of technology

[0020] The invention provides methods and apparatus for detecting reflex vocal cord closure. The vocal cord closure detector derives a measure indicative of the closure. Preferably, the measure is indicative of a state of sleep and may be derived from respiratory airflow of the patient as a function of a minute ventilation and an elapsed time. The delivery of positive airway pressure treatment is controlled as a function of the measure. In the preferred embodiment of the invention, any apnea or obstructive event detected before about 30 minutes of sleep is determined to be vocal cord closure and treatment levels are not increased. Apneas detected after these thresholds are met and treated as a non-vocal cord obstructive apnea by an increase in pressure. Alternatively, reflex vocal cord closure may be detected by distinguishing an incident of vocal cord closure from another type of airway obstruction based on a derived measure indicative of vocal cord closure. The step of distinguishing may include detecting an obstructive event and conditioning an increase in treatment pressure in response to the detected obstructive event by an analysis of the derived measure of the closure. This analysis may include a comparison of the derived measure with a time limit of about 30 minutes. The invention further includes methods and apparatus for providing a synchronized cardiac waveform to perform some work of the cardiac organ. The cardiac waveform may be a square wave or sinusoidal wave in phase with detected cardiac rhythm and is preferably superimposed with continuous, bi-level or other oscillatory respiratory treatment pressure that supports the patient's respiration or maintains an open airway. The cardiac waveform is preferably delivered with amplitudes in a range of approximately 1 to 2 cm H2O.

[0021] The invention also includes a means for calculating a heart treatment index to regulate or measure the dose of treatment to the heart from the synchronized oscillations. The measure determines the index as a function of duration and delivered pressure and preferably accounts only for time that the treatment oscillations are actually delivered to the thorax by excluding treatment during closed airway apnea or periods of high leak. In one embodiment of the invention, the index is the product of an average pressure and the duration of treatment.

[0022] Finally, the invention includes methods and apparatus for assessing heart failure in a patient by calculation or determination of a heart failure indicator or index. Such an indicator may be determined from respiratory airflow by assessing an extent of Cheyne-Stokes breathing in the patient or a count of the number of central apneas. Alternative embodiments of the indicator include measures of the duration of waxing and waning cycles or frequency analysis of components of a measure of airflow in a range of frequencies associated with Cheyne-Stokes breathing. In addition, an appropriate indicator may be a measure of minute ventilation compared with a threshold of about 15 L / min. or alternatively a ratio of a minimum and maximum of a measure of ventilation, such as a minute ventilation or a tidal volume. Changes in such indicators taken by comparing or analyzing indicators from a current session with assigned thresholds or predetermined threshold values including indicators from prior sessions provide a diagnostic tool for assessing improvement or deterioration of the patient's condition.

Problems solved by technology

Of course, these numbers do not account for the number of patients in other countries who also suffer from heart failure.

Given these numbers, it is clear that congestive heart failure is a significant human crisis.

As the heart works less efficiently, its capacity to circulate blood decreases and the body's requirements for oxygen are not met.

This loss of contraction results in a decrease in the ability of the heart to force blood through the circulatory system of the body.

Left-sided heart failure occurs when the left ventricle does not sufficiently pump oxygenated blood to the body.

Right-sided heart failure occurs when the right ventricle does not pump adequately, which leads to fluid build-up in the veins.

This congestion is more commonly a symptom of systolic and left-sided heart failure.

At present, there are no known devices with features designed to treat a range of symptoms of heart failure patients through application of pressure as opposed to devices that might only incidentally provide such benefits.

However, the device is only taught to provide one continuous level of pressure during inspiration and another level during expiration.

Moreover, the device provides no assistance directed to alleviating Cheyne-Stokes breathing or distinguishing between obstructions due to vocal cord reflex and obstructions from typical OSA due to collapse of the upper airway during sleep.

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