Minute volume sensor optimization using quadripolar leads

An apparatus comprising:

• an impedance sensing circuit configured for coupling electrically to a plurality of electrodes and for sensing an impedance signal representative of respiration of a subject;
• and
• a control circuit electrically coupled to the impedance sensing circuit and configured to:
• initiate sensing values of impedance of different electrode combinations of the plurality of electrodes;
• and
• determine an electrode combination from the plurality of electrodes according to the values of impedance for use with the impedance sensing circuit in monitoring respiration of the subject.

An apparatus comprising:

• a respiration sensing circuit configured for coupling electrically to a plurality of electrodes and for sensing a respiration signal representative of respiration of a subject;
• a cardiac signal sensing circuit configured for coupling electrically to the plurality of electrodes and to sense cardiac activation of the subject using the electrodes;
• a stimulus circuit configured for coupling electrically to the plurality of electrodes and to provide pacing pulse stimulation energy to the subject;
• and
• a control circuit configured to:
• initiate delivery of pacing pulses using combinations of the electrodes that include one electrode of the plurality of electrodes as a pacing cathode and the other electrodes as the pacing anode;
• initiate sensing of cardiac activation resulting from the pacing pulses;
• determine a cardiac capture pulse energy level threshold for the electrodes using the sensed cardiac activation;
• and
• enable an electrode combination from the plurality of electrodes having the highest determined cardiac capture pulse energy level threshold for use in monitoring respiration of the subject.