Transesophageal or transtracheal cardiac monitoring by optical spectroscopy

A system useable for monitoring a physiological variable in a target tissue or body fluid located within the thorax of a subject by optical spectroscopy, said system comprising:

• an elongate body configured for insertion into the esophagus, trachea or bronchus of the subject;
• an optical spectroscopy system which is useable for measuring the physiological variable located on or in the elongate body, said optical spectroscopy system comprising i) an emitter for emitting light in the wavelength range of 200-2500 nm through the wall of the esophagus and into a target tissue or body fluid located in the heart, chamber of the heart or intrathoracic blood vessel and ii) a detector for detecting light that has been emitted from the emitter after said light has undergone dispersion and/or reflection by the target tissue or body fluid;
• a positional sensor system useable to track rotational and longitudinal movement of the elongate member within the trachea, esophagus or bronchus relative to the location of the target tissue or body fluid;
• and
• a processing device which receives signals from the positional sensor system and optical spectroscopy system, said processing device being programmed to a) use signals received from the positional sensor system to determine an optimal position of the elongate member for monitoring the target tissue or body fluid by the optical spectroscopy system and b) use signals received from the optical spectroscopy system, while the elongate member is positioned at the optimal position, to estimate at least one physiological variable within the target tissue or body fluid.