A cardiac rhythm management (CRM) device detects transthoracic impedance, extracts ventilation or other information, and adjusts a delivery rate of the CRM therapy accordingly. A four-phase sequence of alternating direction current pulse stimuli is periodically delivered to a patient's thorax. A transthoracic...http://www.google.ca/patents/US6161042?utm_source=gb-gplus-sharePatent US6161042 - Rate adaptive cardiac rhythm management device using transthoracic impedance
