Method and device for measuring parameters of cardiac function

Abstract

A device for non-invasively measuring parameters of a cardiac blood vessel in a patient is provided. The device comprises at least one light source that emits light in the 400 nm to 1000 nm wavelength range and at least one photodetector adapted to receive light emitted by the light source, which light is reflected from or transmitted through tissue of the patient, the output of said photodetector correlating with a parameter of the blood vessel. The device also includes a probe which permits delivery of light from the light source to an external tissue site on the patient in the proximity of a cardiac blood vessel and permits the photodetector to receive light originating from the light source which has been reflected from or transmitted through tissue at the patient site.

We claim: 
     
         1 . A device for non-invasively measuring at least one parameter of a cardiac blood vessel in a patient comprising:
 at least one light source that emits light in the 400 nm to 1000 nm wavelength range;   at least one photodetector adapted to receive light emitted by the light source, wherein said light is reflected from or transmitted through tissue of the patient, the output of said photodetector correlating with a parameter of the blood vessel; and   a probe which permits delivery of light from the light source to an external tissue site on the patient in the proximity of a cardiac blood vessel and permits transfer of light from said light source which is reflected from or transmitted through said patient site.   
     
     
         2 . A device as defined in  claim 1 , additionally comprising a signal-producing means in communication with the photodetector, said signal-producing means being capable of translating the light received from the photodetector into a recordable signal to generate a wave form of the blood vessel. 
     
     
         3 . A device as defined in  claim 1 , adapted to emit and receive light of at least two different wavelengths in the 400 nm to 1000 nm wavelength range. 
     
     
         4 . A device as defined in  claim 1 , comprising at least two photodetectors, each of said photodetectors adapted to receive light at a distinct wavelength,  5 . A method for measuring the waveform of a cardiac blood vessel in a patient comprising the steps of:
 directing a beam of light having a wavelength in the range of 400 nm to 1000 nm at an external tissue site on the patient that is in the proximity of the blood vessel;   detecting light reflected from the tissue site or transmitted through the tissue site; and   translating the detected light into an output signal against time to generate a waveform for the selected blood vessel.   
     
     
         6 . A method as defined in claim  5 , comprising directing more than one beam of light at the same or different tissue site on a patient, each beam having a different wavelength in the range of 400 nm to 1000 nm. 
     
     
         7 . A method as defined in  claim 6 , wherein the light of each wavelength is detected to generate a waveform for two different blood vessels. 
     
     
         8 . A method for measuring the blood content of a chromophore in a patient comprising:
 directing light having at least first and second selected wavelengths at an external tissue site on the patient that is in the proximity of a cardiac blood vessel, wherein said selected wavelengths are based on the absorption characteristics of the chromophore;   detecting light reflected from the tissue or transmitted through the tissue at the selected wavelengths; and   translating the detected light into an output signal against time to generate a waveform for each selected wavelength in order to determine the blood content of said chromophore.   
     
     
         9 . A device as defined in  claim 1 , wherein the parameter is selected from the group consisting of blood vessel pulse, blood vessel volume, blood vessel oxygenation, blood vessel flow and blood vessel content. 
     
     
         10 . A device as defined in  claim 1 , wherein the device produces a waveform of the blood vessel.