Methods, systems, and devices for detecting sleep and apnea events

A method for use by an implantable medical device (IMD) including sensing circuitry, electrodes, an accelerometer, and at least one processor, the method comprising:

• using the sensing circuitry, coupled to the electrodes, to sense an electrocardiogram (ECG) or electrogram (EGM) signal indicative of cardiac electrical activity of a patient's heart;
• using the accelerometer to obtain posture information and activity information for the patient;
• during a first period of time, the at least one processor classifying the patient as being asleep based on the posture information and the activity information obtained from the accelerometer, and in response thereto the at least one processor enabling monitoring for apnea, which includes
• determining a measure of short-term variation (STV) and a measure of long-term variation (LTV) of a feature of the ECG or EGM signal over a measurement period that includes a plurality of cardiac cycles;
• and
• detecting a potential apnea event in the measurement period based on the measure of STV and the measure of LTV in the feature of the ECG or EGM signal;
• wherein the feature comprises one of a morphological feature or a temporal feature;
• and
• during a second period of time, the at least one processor classifying the patient as being awake based on further posture information and further activity information obtained from the accelerometer, and in response thereto the at least one processor disabling the monitoring for apnea.

A non-transitory computer readable medium storing instructions to detect an apnea event that, when executed by at least one processor of an implantable medical device (IMD) that also includes an accelerometer, sensing circuitry, and electrodes, causes the at least one processor to perform operations, comprising:

• obtaining an electrocardiogram (ECG) or electrogram (EGM) signal indicative of cardiac electrical activity of a patient's heart using the sensing circuitry, coupled to the electrodes;
• obtaining posture information and activity information from the accelerometer;
• during a first period of time, classifying the patient as being asleep based on the posture information and the activity information obtained from the accelerometer, and in response thereto enabling monitoring for apnea, which includes
• determining a measure of short-term variation (STV) and a measure of long-term variation (LTV) in a feature of the ECG or EGM signal over a measurement period that includes a plurality of cardiac cycles;
• and
• detecting a potential apnea event in the measurement period based on the measure of STV and the measure of LTV in the feature of the ECG or EGM signal;
• wherein the feature comprises one of a morphological feature or a temporal feature;
• and
• during a second period of time, classifying the patient as being awake based on further posture information and further activity information obtained from the accelerometer, and in response thereto disabling the monitoring for apnea.