Devices, systems, and methods for aiding in the detection of a physiological abnormality
The present invention comprises a method for identifying the presence or absence of a pulmonary embolism using a combination of tests and brightline thresholds. The first test is a blood based test measuring D-Dimer concentration and the second test is a respiratory analysis that determines a carboximetry ratio. If the measured D-Dimer value is at or above a threshold indicative of concern and the carboximetry value is equal to or less than a carboximetry ratio threshold, pulmonary embolism is present. If the measured D-Dimer value is at or above a threshold indicative of concern and the respiratory analysis yields a carboximetry ratio greater than the carboximetry ratio threshold, test results are inconclusive and additional testing is required to determine whether a pulmonary embolism is present.
1. A method for identifying pulmonary embolism in patients, the method comprising the steps of:
a) measuring a D-dimer concentration in a blood sample;
b) determining whether the measured D-dimer concentration is between 100 and 2000 nanograms per milliliter;
c) performing, a respiratory test comprising the steps of:
i) measuring a concentration of produced carbon dioxide in a volume of exhaled air;
ii) measuring a concentration of unconsumed oxygen in the volume of exhaled air;
iii) calculating a carbox ratio wherein the carbox ratio represents the concentration of produced carbon dioxide in relation to the concentration of unconsumed oxygen;
iv) determining whether the calculated carbox ratio is less than or equal to a carbox ratio threshold in a range of 0.25 and 0.30; and
d) outputting an indication, in cases when the measured D-dimer concentration is between 100 and 2000 nanograms per milliliter and the calculated carbox ratio is less than or equal to the carbox ratio threshold in the range of 0.25 and 0.30, that a pulmonary embolism is likely; or
e) outputting an indication, in cases when the measured D-dimer concentration is between 100 and 2000 nanograms per milliliter and the calculated carbox ratio is greater than the carbox ratio threshold in the range of 0.25 and 0.30, that additional diagnostic testing is required; or
f) outputting an indication, in cases when the D-dimer concentration is not between 100 and 2000 nanograms per milliliter and the calculated carbox ratio is greater than the carbox ratio threshold in the range of 0.25 and 0.30, that a pulmonary embolism is unlikely.
2. The method of claim 1 , wherein the threshold indicative of concern is between 500 and 1000 nanograms per milliliter.
3. The method of claim 1 wherein the threshold indicative of concern is 500 nanograms per milliliter.
4. The method of claim 1 , wherein the carbox ratio threshold is 0.28.
5. The method of claim 1 further comprising the step of heating the volume of exhaled air to prevent condensation from forming.
6. The method of claim 1 wherein the threshold indicative of concern is about 500 nanograms per milliliter and the carbox ratio threshold is about 0.28.
7. A method for identifying pulmonary embolism in patients, the method comprising the steps of:
a) determining whether a concentration of D-dimer in a blood sample is at 100 and 2000 nanograms per milliliter;
b) determining whether a carbox ratio of a volume of exhaled air is in the range of 0.25 and 0.30; and
c) outputting an indication, in cases when the measured D-dimer concentration is between 100 and 2000 nanograms per milliliter and the calculated carbox ratio is less than or equal to the carbox ratio threshold in the range of 0.25 and 0.30, that a pulmonary embolism is likely; or
d) outputting an indication, in cases when the measured D-dimer concentration is between 100 and 2000 nanograms per milliliter and the calculated carbox ratio is greater than the carbox ratio threshold in the range of 0.25 and 0.30, that additional diagnostic testing is required; or
e) outputting an indication, in cases when the D-dimer concentration is not between 100 and 2000 nanograms per milliliter and the calculated carbox ratio is greater than the carbox ratio threshold in the range of 0.25 and 0.30, that a pulmonary embolism is unlikely.
8. The method of claim 7 , wherein the threshold indicative of concern is between 500 and 1000 nanograms per milliliter.
9. The method of claim 7 wherein the threshold indicative of concern is 500 nanograms per milliliter.
10. The method of claim 7 , wherein the carbox ratio threshold is 0.28.
11. The method of claim 7 further comprising the step of heating the volume of exhaled air to prevent condensation from forming.
12. The method of claim 7 wherein the threshold indicative of concern is about 500 nanograms per milliliter and the carbox ratio threshold is about 0.28.