Detection of heart failure using a photoplethysmograph

Apparatus for diagnosis, comprising:

• a sensor, which is configured to be coupled to a body of a patient during sleep and to output a signal associated with blood oxygen saturation in the body;
• and
• a processor, which is coupled to filter the signal so as to eliminate signal components at frequencies equal to and greater than a respiratory frequency of the patient, and to process the filtered signal to determine a slope of the filtered signal, to distinguish Cheyne-Stokes breathing events from obstructive apnea events responsively to the slope, and to detect a pattern corresponding to multiple cycles of periodic breathing based on the distinguished Cheyne-Stokes breathing events.

A computer software product, comprising:

• a computer-readable medium in which program instructions are stored, which instructions, when read by a computer, cause the computer to receive a signal associated with blood oxygen saturation in a body or a patient, and to filter the signal so as to eliminate signal components at frequencies equal to and greater than a respiratory frequency of the patient, and to process the filtered signal to determine a slope of the filtered signal, to distinguish Cheyne-Stokes breathing events from obstructive apnea events responsively to the slope, and to detect a pattern corresponding to multiple cycles of periodic breathing based on the distinguished Cheyne-Stokes breathing events.

A method for diagnosis, comprising:

• receiving a signal associated with blood oxygen saturation of a patient during sleep;
• filtering the signal so as to eliminate signal components at frequencies equal to and greater than a respiratory frequency of the patient;
• operating a computer for processing the filtered signal to distinguish Cheyne-Stokes breathing events from obstructive apnea events and to detect a pattern corresponding to multiple cycles of periodic breathing based on the distinguished Cheyne-Stokes breathing events.