Non-contact respiration rate and apnea monitor using pulmonary gas exchange technique

摘要

An apnea detector uses an active pulsed source of radiation to monitor the respiration of a patient. Radiation from the source is formed into a collimated beam that is directed through the space into which the patient is breathing. The exhaled gases contain a smaller concentration of oxygen and a larger concentration of carbon dioxide compared with the atmosphere. Each exhalation of the patient produces a small cloud of the exhaled gases, which rapidly diffuse and disperse. Corresponding to the appearance and disappearance of these clouds of gas, the transmission of the collimated beam will vary in step with the patient's breathing. The fluctuations in the transmitted radiation are analyzed by a signal processor which generates an alarm signal when either the magnitude or the frequency of these fluctuations falls outside of preset limits. Either carbon dioxide or oxygen may be monitored as the absorbing gas.