A cardiac rhythm management apparatus and system may include a first sensor to sense an atrial respiration signal, a second sensor to sense a ventricular respiration signal, and a measurement module capable of being communicatively coupled to the first and second sensors to monitor the atrial and ventricular respiration signals and to select a resulting signal as an indication of respiration. An article may cause a machine to implement a method which includes measuring a second signal responsive to a first signal, measuring a third signal responsive to a first signal, determining a respiration-to-cardiac ratio associated with each one of the second and third signals, and providing a resulting signal including a selected portion of a selected one of the second and third signals as an indication of respiration.