Fiber optic system for measuring cardiac output
OwnerMarcos Y. Kleinermaninventor
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Abstract
The method subject of the invention is based on fiber optic technology, and in particular on the light transmission changes at a wavelength or wavelengths .lambda..sub.s within an optical absorption band of hemoglobin occurring over a length of bare core of an optical fiber, inserted in an artery and covered with the patient's blood, when a clear aqueous saline or dextrose solution, optically transparent at said wavelength or wavelengths .lambda..sub.s, displaces much of the blood as it flows around the fiber core under the heart's pumping action.
Claims6
A fiber optic method for measuring cardiac output, comprising the steps of:
- (a) inserting into a blood vessel, when said vessel carries blood including hemoglobin-containing red cells flowing along it, an optical fiber having a proximal end and a distal end, the fiber having a core and a cladding around and in contact with said core over most of the length of the fiber, the fiber including a segment at or near the fiber distal end wherein the cladding does not cover the core, the core being bare but otherwise intact along the length of said segment;
- (b) launching interrogating light of wavelengths .lambda..sub.s, within an absorption band of the hemoglobin of said red blood cells and of pre-selected intensity into the fiber at the proximal end thereof, said light propagating along the fiber towards said distal end, at least a fraction of said intensity of said interrogating light being absorbed by said red blood cells;
- (c) injecting into said blood vessel a clear aqueous solution at a distance from said bare segment of the fiber core such that said clear solution flows toward said bare segment under the action of the blood flow, thus causing an increase of the intensity of the interrogating light transmitted by said bare segment of the fiber core;
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- (d) sensing, with photodetector means, the increase of the intensity of the interrogating light transmitted by said bare segment of the fiber core.
An arrangement for measuring cardiac output, comprising:
- (a) an optical fiber having a proximal end and a distal end, the fiber having a core and a cladding around and in contact with said core over most of the fiber length, the fiber including a segment at or near the fiber distal end wherein the cladding does not cover the core, the core being bare but otherwise intact along the length of said segment;
- (b) means for inserting said fiber into a bloodvessel carrying blood including hemoglobin-containing red cells flowing along it,
- (c) a light source for launching interrogating light of wavelengths .lambda..sub.s within an absorption band of the hemoglobin of said red blood cells and of pre-selected intensity into the fiber at the proximal end thereof, said light propagating along the fiber towards said distal end;
- (d) means for injecting into said blood vessel a clear aqueous solution at a distance upstream from said bare fiber core such that said clear solution flows toward said bare core and reaches said bare fiber core in a time shorter than fifty seconds, thus causing an increase of the intensity of the interrogating light transmitted by said bare segment of the fiber core;
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- (e) photodetector means for sensing the changes in the intensity of the interrogating light transmitted by said bare fiber core as at least part of said clear solution flows over it.
Dependencies are inferred from the claim text.