DEVICES, SYSTEMS, AND METHODS FOR AIDING IN THE DETECTION OF A PHYSIOLOGICAL ABNORMALITY

• US 20110009764A1
• Filed: 07/13/2010
• Published: 01/13/2011
• Est. Priority Date: 04/14/2009
• Status: Abandoned Application

• Current Assignee: Deka Products Limited Partnership
• Original Assignee: Deka Products Limited Partnership
• Inventors: Lanier, Gregory R., Kane, Derek
• Application Number:
  US12/835,548
• Publication Number:
  US 20110009764A1
• Time in Patent Office: Days
• US Class Current: 600/532
• CPC Class Codes: A61B 2560/0252 using ambient temperature
• CPC Class Codes: A61B 2560/0431 Portable apparatus, e.g. comprising a handle or case
• CPC Class Codes: A61B 2560/0462 Apparatus with built-in sensors
• CPC Class Codes: A61B 5/0833 Measuring rate of oxygen consumption
• CPC Class Codes: A61B 5/0836 Measuring rate of CO2 production
• CPC Class Codes: A61B 5/087 Measuring breath flow
• CPC Class Codes: A61B 5/097 Devices for facilitating collection of breath or for directing breath into or through measuring devices
• CPC Class Codes: A61B 5/411 Detecting or monitoring allergy or intolerance reactions to an allergenic agent or substance
• CPC Class Codes: A61B 5/417 the bone marrow
• CPC Class Codes: A61B 5/743 Displaying an image simultaneously with additional graphical information, e.g. symbols, charts, function plots
• CPC Class Codes: A61B 5/7435 Displaying user selection data, e.g. icons in a graphical user interface

Abstract

The present invention comprises a method for excluding the presence of a pulmonary embolism using a combination of a blood test for D-dimer and a carboximetry test measuring the ratio of exhaled CO₂ to O₂. If the measured D-Dimer value is at or above a threshold indicative of concern and the carboximetry value is equal to or greater than a pre-determined carboximetry ratio threshold, a clinically significant pulmonary embolism, or a pulmonary thrombus above a certain effective size, is unlikely to be present. If the measured D-Dimer value is at or above a threshold indicative of concern and the respiratory analysis yields a carboximetry ratio less than the carboximetry ratio threshold, test results are inconclusive and additional testing may be required to determine whether a clinically significant pulmonary embolism, or a pulmonary thrombus above a specified size is present. The present invention also comprises a method for diagnosing or excluding the presence of respiratory dysfunction in an individual by using carboximetry values corresponding to an end-tidal volume of an exhaled breath that is a pre-determined multiple of the individual'"'"'s estimated pulmonary dead space. In one aspect, a linear regression function is used to represent the CO₂/O₂ ratio derived from the measured CO₂ and O₂ values in an exhaled breath, and the function is used to determine the CO₂/O₂ ratio corresponding to the pre-determined end-tidal volume.

Claims

1. A method to aid in the diagnosis of respiratory dysfunction in an individual, comprising:

a) estimating the pulmonary dead space in the individual;

b) measuring the volume of air exhaled in each of a series of breaths by the individual;

c) measuring a concentration of carbon dioxide and a concentration of oxygen in each of the exhaled breaths;

d) calculating a final carbox ratio comprising an exhaled carbon dioxide concentration divided by an exhaled oxygen concentration at a pre-determined volume of each exhaled breath, the pre-determined volume being a multiple of the individual'"'"'s pulmonary dead space; and

e) comparing an average or median value of the final carbox ratios from the series of breaths to a known value;

wherein

the presence of respiratory dysfunction is indicated if the average or median value is below the known value, and the absence of respiratory dysfunction is indicated if the average or median value is at or above the known value.

2. The method of claim 1, wherein the pre-determined volume of exhaled breath is within the range of about 2 times the pulmonary dead space to about 5 times the pulmonary dead space.

3. The method of claim 1, wherein the pre-determined volume of exhaled breath is within the range of about 2.5 times the pulmonary dead space to about 4 times the pulmonary dead space.

4. The method of claim 1, wherein the pre-determined volume of exhaled breath is about 3 times the pulmonary dead space.

5. The method of claim 1, wherein calculating the final carbox ratio for an exhaled breath comprises dividing the measured carbon dioxide concentration by the measured oxygen concentration corresponding to each of a series of exhaled breath volumes to generate a series of measurement-based carbox ratios, fitting an n^th order equation to the series of measurement-based carbox ratios, and selecting the final carbox ratio for the pre-determined volume of exhaled breath from the fitted equation, wherein

n is equal to or greater than 1.

6. The method of claim 5, wherein the n^th order equation is a first order equation.

7. The method of claim 1, wherein calculating the final carbox ratio for an exhaled breath comprises fitting a first n^th order equation to a series of measured carbon dioxide concentrations in each of a series of exhaled breaths, fitting a second n^th order equation to a series of measured oxygen concentrations in each of the series of exhaled breaths, selecting a fitted value for carbon dioxide and a fitted value for oxygen corresponding to the pre-determined volume of exhaled breath, and dividing the fitted value for carbon dioxide by the fitted value for oxygen to yield a derived final carbox ratio for each exhaled breath, wherein n for the first equation is equal to or greater than 1, and n for the second equation is equal to or greater than 1.

8. The method of claim 7, wherein the first n^th order equation and the second n^th order equation are both first order equations.