System and method for apnea detection

An impedance-based respiration monitoring system, comprising:

• at least three surface electrodes configured to record impedance respiration data from a patient's torso;
• a signal processing system configured to:
• generate a first respiration lead formed by a first set of surface electrodes from the at least three surface electrodes, the first respiration lead providing a first series of impedance measurements;
• and
• generate at least a second respiration lead formed by a second set of surface electrodes from the at least three surface electrodes attached to the patient's torso, the second lead providing a second series of impedance measurements;
• wherein the first series of impedance measurements is generated by injecting and detecting a first carrier frequency in the first set of electrodes, and the second series of impedance measurements is generated by injecting and detecting a second carrier frequency in the second set of electrodes;
• wherein the first series of impedance measurements from the first respiration lead measures thoracic breath activity, and wherein the second series of impedance measurements from the second respiration lead measures abdominal breath activity;
• wherein the first set of electrodes includes a first electrode and a second electrode, and the second set of electrodes includes the second electrode and a third electrode, and wherein the system is configured to:
• inject the first carrier frequency at a first phase into the first electrode, and receive the first carrier frequency at the first phase at the second electrode;
• inject the first carrier frequency at a second phase into the second electrode, and receive the first carrier frequency at the second phase at the first electrode;
• inject the second carrier frequency at a first phase into the second electrode, and receive the second carrier frequency at the first phase at the third electrode;
• inject the second carrier frequency at a second phase into the third electrode, and receive the second carrier frequency at the second phase at the second electrode;
• determine the first series of impedance measurements based on the first carrier frequency received at the first and second electrodes;
• determine the second series of impedance measurements based on the second carrier frequency received at the first and second electrodes;
• a respiration detection module executable on a processor to:
• calculate a first respiration metric based on the first series of impedance measurements;
• calculate a second respiration metric based on the second series of impedance measurements;
• and
• detect a respiration event only when the first respiration metric indicates insufficient breath activity occurring at the patient's chest and the second respiration metric indicates insufficient breath activity occurring at the patient's abdomen.