Fiber optic interferometric vital sign monitor for use in magnetic resonance imaging, confined care facilities and in-hospital

Abstract

A fiber optic monitor that utilizes optical phase interferometry to monitor a patient's vital signs such as respiration, cardiac activity, blood pressure and body's physical movement. The monitor, which is non-invasive, comprises an optical fiber interferometer that includes an optical fiber proximately situated to the patient so that time varying acousto-mechanical signals from the patient are coupled into the optical fiber. Responsive thereto, the interferometer generates a time-varying optical intensity resulting from the interference of optical signals, which are detected at a photo-detector. A signal processor coupled to the optical detector provides one or more processed output signals indicative of the vital functions. The monitor system has broad applicability, from routine monitoring of infants at home to detection of apnea, arrhythmia, blood pressure and trauma. The system can be implemented in embodiments ranging from a low cost in-home monitor for infants to a high end product for in hospital use. The monitor can be integrated with other sensors such as an EKG, a video or still camera, an oxygen sensor, a carbon dioxide sensor, temperature sensor or a microphone to get additional required information depending on the application. When integrated and combined with EKG information, the monitor provides ballisto-mechanical information of the heart for early diagnosis of cardiac conditions or prediction of events or for correcting corrupted EKG signals due to time varying magnetic and electric fields. In some embodiments of the monitor, the system can be made portable so that the patient can walk around while still being continuously monitored for vital signs. Another suitable design measures blood pressure continuously and non-invasively by containing the fiber optic sensor in a cuff that wraps around an arterial wall of the patient. The fiber optic monitor may be designed for use in a variety of settings including an operating room, a recovery room, an intensive care unit, a magnetic resonance imaging laboratory, a computerized tomography scan laboratory and an elderly care facility.