Method and system for determining placement of a tracheal tube in a subject
According to various embodiments, a tracheal tube may employ optical sensing techniques for determining a distance between the inserted tube and an anatomical structure, such as a carina. The distance information may provide an indication as to whether or not the tracheal tube is properly placed within the trachea. The optical techniques may include backscattered intensity measurements.
1. A method for determining placement of a tracheal tube in a subject comprising:
emitting light from a plurality of optical conductors circumferentially spaced about a beveled distal end of a tracheal tube disposed in a subject, wherein the beveled distal end is slanted relative to a wall of the tracheal tube such that the plurality of optical conductors are different distances from a carina of the subject;
determining an intensity of the emitted light from each of the respective plurality of optical conductors;
receiving returned light from the carina of the subject;
measuring an intensity of the returned light from each of the respective plurality of optical conductors; and
determining a placement parameter reflective of an angular orientation of the beveled distal end relative to the carina based upon a relationship between the intensity of the returned light and the emitted light from each of the respective plurality of optical conductors and a difference in path length between the plurality of optical conductors, wherein the difference in path length is representative of a position of each respective optical conductor about the distal end.
2. The method of claim 1 , wherein the intensity of the emitted light is measured by a first photodetector and the intensity of the returned light is measured by a second photodetector.
3. The method of claim 1 , wherein the intensity of the emitted light and the intensity of the returned light are measured by a single photodetector.
4. The method of claim 1 , wherein the placement parameter is determined based upon an optical parameter of the carina.
5. The method of claim 1 , wherein the steps are performed during intubation of the subject.
6. The method of claim 1 , wherein the steps are performed after intubation of the subject.
7. A method for determining placement of a tracheal tube in a subject comprising:
emitting light from a plurality of optical conductors circumferentially spaced apart on a beveled distal end of a tracheal tube disposed in a subject, wherein the beveled distal end is slanted relative to a wall of the tracheal tube such that the plurality of optical conductors are different distances from a carina of the subject;
determining an intensity of the emitted light from each of the respective plurality of optical conductors;
receiving returned light from the carina of the subject;
determining an intensity of the returned light from each of the respective plurality of optical conductors; and
determining a placement parameter representative of an orientation of the slanted distal end based upon a difference in path length between the plurality of optical conductors, wherein the difference in path length is representative of a position of each respective optical conductor about the distal end, and an algorithm that implements an equation generally of the form:
R= ½( I o /I r ) 1/2 ,
where R is the placement parameter, is a function of optical properties of the anatomical structure, I o is the intensity of the emitted light, and I r is the intensity of the returned light.
8. The method of claim 7 , wherein the intensity of the emitted light is measured by a first photodetector and the intensity of the returned light is measured by a second photodetector.
9. The method of claim 7 , wherein the intensity of the emitted light and the intensity of the returned light are measured by a single photodetector.
10. The method of claim 7 , wherein the steps are performed during intubation of the subject.
11. The method of claim 7 , wherein the steps are performed after intubation of the subject.
12. A system for determining placement of a tracheal tube in a subject comprising:
a tracheal tube comprising a plurality of optical conductors circumferentially spaced apart on a beveled distal end of the tracheal tube, wherein the beveled distal end is slanted relative to a gas flow pathway of the tracheal tube;
a light source configured to emit light through each of the respective plurality of optical conductors when the tracheal tube is disposed in the subject;
means for determining intensity of the emitted light from each of the respective plurality of optical conductors;
a photodetector configured to receive returned light emitted from each of the respective plurality of optical conductors after interaction with a carina of the subject and to determine an intensity of the returned light from each of the respective plurality of optical conductors; and
a processor configured to determine an orientation of the beveled distal end of the tracheal tube based upon the intensity of the returned light from each of the respective plurality of optical conductors and a difference in path length between the plurality of optical conductors, wherein the difference in path length is representative of a position of each respective optical conductor about the distal end.
13. The system of claim 12 , wherein the means for determining the intensity of the emitted light comprises the photodetector.
14. The system of claim 12 , wherein the processor is configured to determine the placement parameter based upon an algorithm that implements an equation generally of the form:
R= ½( I o /I r ) 1/2 ,
where R is the placement parameter, is a function of optical properties of the anatomical structure, I o is the intensity of the emitted light, and I r is the intensity of the returned light.