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US 2003/0120162 A1Published application
Method for measuring blood flow
AssigneeThermal Technologies, Inc.
InventorHarry Frederick Bowman
Life of this patent
Estimating the term…
Abstract
A technique for determining blood flow in a living body by changing the thermal energy level by a predetermined amount at a site in a blood flow path and detecting temperatures at locations upstream and downstream of the site. The temperature difference at such locations is determined and the blood flow is calculated as a function of the change in energy level and of the temperature differences measured prior to and following the change in energy level.
Claims46
A method for determining blood flow in a living body comprising the steps of:
- changing the thermal energy level by a predetermined amount at a site in a blood flow path of said living body;
- detecting the temperatures at a first location upstream of said site and a second location downstream of said site;
- determining the temperature difference between said first and second locations at one energy level;
- determining the temperature difference between said first and second locations at a changed energy level;
- and
- calculating blood flow as a function of the change in energy level and of the temperature differences measured prior to and following the change in energy level.
3 more elements
A method for determining blood flow in a living body comprising the steps of:
- changing the thermal energy at a site in a blood flow path of said living body, from a first level to a second level;
- determining a characteristic of the temperature difference between the temperatures in said blood flow path at a first location upstream of said site and at a second location downstream of said site at said first level;
- determining a characteristic of the temperature difference between the temperatures in said blood flow path at the first location and at the second location at said second level;
- determining the difference between the characteristics of said temperature differences;
- calculating blood flow as a function of the difference between the characteristics of said temperature differences and the change in thermal energy from said first level to said second level.
2 more elements
A system for determining blood flow in a living body comprising:
- means for changing the thermal energy level by a predetermined amount at a site in a blood flow path of said living body;
- means for detecting the temperatures at a first location upstream of said site and a second location downstream of said site;
- means for determining the temperature difference between said first and second locations at one energy level;
- means for determining the temperature difference between said first and second locations at a changed energy level;
- and
- means for calculating blood flow as a function of the change in energy level and of the temperature differences measured prior to and following the change in energy level.
3 more elements
A system for determining blood flow in a living body comprising:
- means for changing the thermal energy at a site in a blood flow path of said living body, from a first level to a second level;
- means for determining a characteristic of the temperature difference between the temperatures in said blood flow path at a first location upstream of said site and at a second location downstream of said site at said first level;
- means for determining a characteristic of the temperature difference between the temperatures in said blood flow path at the first location and at the second location at said second level;
- means for determining the difference between the characteristics of said temperature differences;
- means for calculating blood flow as a function of the difference between the characteristics of said temperature differences and the change in thermal energy from said first level to said second level.
2 more elements
A method for determining blood flow in a living body comprising the steps of:
- changing the value of the selected parameter of blood at a site in a blood flow path of said living body, from a first level to a second level;
- determining the difference between the value of the selected parameter in said blood flow path at a first location upstream of said site and at a second location downstream of said site at said first level;
- determining the difference between the value of the selected parameter in said blood flow path at the first location and at the second location at said second level;
- determining the difference between the value obtained in the first said difference determining steps and the value obtained in the second said difference determining steps;
- and
- calculating blood flow as a function of the difference between the values obtained in said first and second difference determining steps and the change in the value of the selected parameter from said first level to said second level.
3 more elements
A system for determining blood flow in a living body comprising:
- means for changing the value of the selected parameter of blood at a site in a blood flow path of said living body, from a first level to a second level;
- means for determining the difference between the value of the selected parameter in said blood flow path at a first location upstream of said site and at a second location downstream of said site at said first level;
- means for determining the difference between the value of the selected parameter in said blood flow path at a first location upstream of said site and at a second location downstream of said site at said first level;
- means for determining the difference between the value of the selected parameter in said blood flow path at the first location and at the second location at said second level;
- means for determining the difference between the value obtained in the first said difference determining steps and the value obtained in the second said difference determining steps;
- and
- means for calculating blood flow as a function of the difference between the values obtained in said first and second difference determining steps and the change in the value of the selected parameter from said first level to said second level.
4 more elements
A method for determining instantaneous blood flow in a living body comprising the steps of:
- determining the temperature level at a selected location in a blood flow path of said living body;
- heating said selected location in said blood flow path to a final temperature level;
- determining the final temperature level;
- determining the ratio of the heating power required to heat said selected location to said final temperature level to the change in temperature level at said selected location.
1 more element
A device for insertion into the bloodstream of a living organism to obtain physiological data comprising:
- an elongated flexible catheter adapted to be inserted into the venous or arterial system of the living organism;
- first temperature sensing means carried by said catheter;
- second temperature sensing means carried by said catheter positioned to be upstream of said first temperature sensing means when in use;
- and
- heating means carried by said catheter between said first and second temperature sensing means and positioned to be substantially thermally isolated from said second temperature sensing means when in use;
- said first and second temperature sensing means and said heating means being adapted to be in communication with a data processing system.
3 more elements
A device for insertion into the bloodstream of a living organism to obtain physiological data comprising:
- an elongated flexible catheter adapted to be inserted into the venous or arterial system of the living organism;
- temperature sensing means carried by said catheter;
- and
- thermistor means carried by said catheter and positioned to be downstream of said temperature sensing means when in use;
- said temperature sensing means and said thermistor means being adapted to be in communication with a data processing system.
2 more elements
Dependencies are inferred from the claim text.