The patient monitor includes a patient unit having a probe connected to receive a carrier signal, which probe is adapted for connection to the body of a patient to be monitored. The carrier signal is passed through the patient's body and modulated in accordance with the respirations of the patient to...http://www.google.com/patents/US4713558?utm_source=gb-gplus-sharePatent US4713558 - Patient monitor for providing respiration and electrocardiogram signals
