Methods of non-invasively estimating intrapulmonary shunt fraction and measuring cardiac output
First Claim
1. A method of estimating an intrapulmonary shunt of a patient, comprising:
- determining a respiratory flow and a respiratory carbon dioxide fraction of respiration of the patient;
calculating a carbon dioxide elimination of the patient;
calculating an end capillary blood oxygen content of the patient;
determining an arterial blood oxygen saturation of the patient;
correcting for an inaccuracy of said arterial blood oxygen saturation; and
calculating an intrapulmonary shunt fraction with said end capillary blood oxygen content, said arterial blood oxygen saturation, said carbon dioxide elimination, and a respiratory quotient of the patient.
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Abstract
A method of non-invasively estimating the intrapulmonary shunt in a patient. The method includes non-invasively measuring respiratory flow, respiratory carbon dioxide content, and arterial blood oxygen content. A re-breathing process is employed to facilitate an estimate of the patient'"'"'s pulmonary capillary blood flow. Any inaccuracies of the arterial blood oxygen content are corrected to provide a substantially accurate arterial blood oxygen content measurement. The respiratory flow and carbon dioxide content and arterial blood oxygen content measurements, and the pulmonary capillary blood flow estimate are employed to estimate an intrapulmonary shunt of the patient. The invention also includes a method of determining the total cardiac output of the patient which considers the estimated intrapulmonary shunt.
75 Citations
26 Claims
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1. A method of estimating an intrapulmonary shunt of a patient, comprising:
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determining a respiratory flow and a respiratory carbon dioxide fraction of respiration of the patient; calculating a carbon dioxide elimination of the patient; calculating an end capillary blood oxygen content of the patient; determining an arterial blood oxygen saturation of the patient; correcting for an inaccuracy of said arterial blood oxygen saturation; and calculating an intrapulmonary shunt fraction with said end capillary blood oxygen content, said arterial blood oxygen saturation, said carbon dioxide elimination, and a respiratory quotient of the patient. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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26. A method of determining an intraoulmonary shunt fraction of a patient, comprising:
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non-invasively determining an oxygen saturation of arterial blood of the patient; determining a fraction of inspired oxygen of the patient; re-breathing to determine a pulmonary capillary blood flow of the patient; and employing said oxygen saturation of arterial blood and said fraction of inspired oxygen with an iso-shunt plot.
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Specification