Methods of measuring cardiac output using a non-invasively estimated intrapulmonary shunt fraction
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; and
calculating an intrapulmonary shunt fraction with said end capillary blood oxygen content, said arterial blood oxygen saturation, and said carbon dioxide elimination.
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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, 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.
33 Citations
31 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; and
calculating an intrapulmonary shunt fraction with said end capillary blood oxygen content, said arterial blood oxygen saturation, and said carbon dioxide elimination. - 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, 26, 27, 28)
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29. A method of determining an intrapulmonary 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;
determining a pulmonary capillary blood flow of the patient; and
employing said oxygen saturation of arterial blood and said fraction of inspired oxygen to determine the intrapulmonary shunt fraction. - View Dependent Claims (30, 31)
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Specification