Method and apparatus for assessing hemodynamic parameters within the circulatory system of a living subject

1. An apparatus for locating a blood vessel having a lumen, said apparatus comprising:

a transducer element adapted to transmit acoustic energy into said blood vessel; and

a processor element adapted to:

determine a power of backscatter energy from said transmitted energy as a function of depth within said blood vessel;

identify at least one artifact associated with a location of said lumen;

compute a power function in a first dimension relative to said location; and

compute a power function in a second dimension relative to said location;

wherein said computations substantially determine a location of said blood vessel.

2. The apparatus of claim 1 , wherein said identification is performed via a method that identifies at least one plateau.

3. The apparatus of claim 1 , wherein said identification is performed via a method that specifies at least one interval.

4. A method of locating a blood vessel having a lumen, comprising:

transmitting acoustic energy into said blood vessel via a transducer;

receiving a signal related to backscattered energy derived from said transmitted acoustic energy at said transducer; and

processing said backscattered energy to identify at least one artifact associated with said lumen at a processor associated with said transducer, said at least one artifact comprising a substantially flat portion of a power profile corresponding to said lumen.

5. The method of claim 4 , wherein said identification of said substantially flat portion comprises:

determining a power metric as a function of depth;

integrating said power metric and normalizing said integrated power metric; and

detecting a plateau associated with said lumen based at least in part on said acts of determining and integrating.

6. Apparatus adapted to detect the location of a blood vessel, comprising:

an acoustic transducer;

a signal transceiver operatively coupled to said acoustic transducer; and

a processor operatively coupled to said signal transceiver, said processor adapted to perform computations on data received by said signal transceiver in order to compute the location of said blood vessel;

wherein said processor is further adapted to;

baseband said received acoustic energy data; and

square said basebanded data to produce envelope-squared data.

7. The apparatus of claim 6 , wherein said acoustic transducer comprises an ultrasonic transducer.

8. The apparatus of claim 6 , wherein said processor basebands said received acoustic energy data by:

multiplication of the received acoustic energy data by a sine and cosine function; and

application of a lowpass filter to said multiplied data to produce said basebanded data.

9. The apparatus of claim 6 , wherein said processor is further adapted to decimate said envelope-squared data to a predetermined sampling rate, and apply a depth-dependent gain to said decimated envelope-squared data.

10. The apparatus of claim 9 , wherein said depth-dependent gain is non-linear.

11. An apparatus for locating a position of a blood vessel having a lumen, said apparatus comprising:

a means for transmitting acoustic energy into said blood vessel;

a means for determining power of backscatter energy from said transmitted energy as a function of depth within said blood vessel;

a means for identifying at least one artifact associated with a location of said lumen; and

a means for calculating:

a power function in a first dimension relative to said location; and

a power function in a second dimension relative to said location;

wherein said means for calculating are utilized to substantially determine a location of said blood vessel.

12. The apparatus of claim 11 , wherein said means for identifying at least one artifact comprise means for identifying at least one plateau.

13. The apparatus of claim 11 , wherein said means for identifying at least one artifact comprise means for identifying at least one interval.

14. A method of locating a blood vessel having a lumen, comprising:

transmitting acoustic energy into said blood vessel via a transducer;

receiving, at said transducer, backscattered energy produced from said transmitted acoustic energy; and

processing, at a processor in signal communication with said transducer, said received backscattered energy to identify at least one artifact associated with said lumen;

wherein said identification of said at least one artifact comprises identification of a substantially flat portion of a power profile corresponding to said lumen.

15. The method of claim 14 , wherein said identification of said substantially flat portion comprises:

determining a power metric as a function of depth;

integrating said power metric and normalizing said integrated power metric; and

detecting a plateau associated with said lumen based at least in part on results from said acts of determining and integrating.

16. The method of claim 15 , wherein:

said identification of said substantially flat portion further comprises dividing said normalized integrated power metric into a number of intervals; and

said detecting said plateau is based at least in part on said acts of determining, integrating and dividing.

17. The method of claim 16 , wherein said dividing is performed in substantially equally spaced intervals.

18. The method of claim 16 , wherein said dividing is performed in substantially non-equally spaced intervals.

19. The method of claim 14 , wherein said processing is performed using an interval-based method.