Ntc Technology, Inc.

Kai K&uuml;ck

Joseph Allen Orr

Michael Brian Jaffe

Dinesh G Haryadi

A method of noninvasively determining the pulmonary capillary blood flow or cardiac output of a patient, including the use of rebreathing techniques to measure the respiratory flow and carbon dioxide pressure of the patient's breathing. These measurements are used to calculate carbon dioxide elimination and an indicator of the carbon dioxide content of the patient's blood, such as the end-tidal pressure of carbon dioxide (PetCO ), CaCO , or pCO . The location and orientation of a best-fit line through the carbon dioxide elimination data and the data of the indicator of carbon dioxide content is determined by linear regression or by plotting the carbon dioxide elimination data against the data of the indicator of carbon dioxide content. At least one set of the data is modified and at least one other determination of the best-fit line made to find a data set that correlates most closely to the best-fit line. The data may be modified by filtering or clustering. The slope of the best-fit line that correlates most closely to the data is then used to determine the pulmonary capillary blood flow or cardiac output of the patient. When the indicator of carbon dioxide content is CaCO , the negative of the slope of the best-fit line is equal to the pulmonary capillary blood flow of the patient.

Methods for accurately, substantially noninvasively determining pulmonary capillary blood flow, cardiac output, and mixed venous carbon dioxide content

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.

Methods of non-invasively estimating intrapulmonary shunt fraction and measuring cardiac output

Methods of measuring cardiac output using a non-invasively estimated intrapulmonary shunt fraction

A method of compensating for non-metabolic changes in respiratory or blood gas parameters including generating a compensatory signal based on the magnitude of the non-metabolic change and the amount of time elapsed since the onset of the non-metabolic change. The method of the present invention is useful for compensating for non-metabolic changes in non-invasive carbon dioxide elimination measurements and, particularly, when carbon dioxide elimination is employed to determine cardiac output on a non-invasive, continuous basis.

Method for compensating for non-metabolic changes in respiratory or blood gas profile parameters

A method of continuously, non-invasively determining the cardiac output of a patient. The method includes intermittently measuring the cardiac output, the volume of carbon dioxide exhaled by the patient per breath, and determining the arterial-venous gradient of the patient or a similar substantially constant value by dividing the volume of carbon dioxide exhaled by the measured cardiac output. The arterial-venous gradient or similar substantially constant value may then be employed to determine the cardiac output of the patient on a breath-by-breath basis. The carbon dioxide elimination, which is non-invasively measured as the volume of carbon dioxide exhaled by the patient per breath, is divided by the arterial-venous gradient or the substantially constant value to determine the cardiac output. The method may also include generating a signal to compensate for any non-metabolic changes in the carbon dioxide elimination, arterial-venous gradient, or other respiratory or blood gas profile measurements that may be caused by a change in ventilation or breathing of the patient. The compensatory signal may be employed to modify one or more of the respiratory or blood gas profile measurements in order to facilitate the accurate determination of cardiac output during or after changes in ventilation or breathing.

Method of continuously, non-invasively monitoring pulmonary capillary blood flow and cardiac output

A re-breathing method for determining pulmonary capillary blood flow that accounts for changes in the cardiac output or in the carbon dioxide content of the venous blood of a patient. The carbon dioxide elimination and partial pressure of end tidal carbon dioxide of the patient are non-invasively measured prior to re-breathing, during re-breathing, and after re-breathing. The carbon dioxide elimination and the carbon dioxide content of the alveolar blood of the patient at each of the before, during, and after re-breathing phases are then used to calculate the pulmonary capillary blood flow of the patient. A rate of change of carbon dioxide content of the venous blood of the patient may also be calculated and employed in calculating the pulmonary capillary blood flow of the patient.

Bi-directional partial re-breathing method

A re-breathing method for determining pulmonary capillary blood flow that accounts for changes in the carbon dioxide content of a patient. The carbon dioxide elimination and partial pressure of end tidal carbon dioxide of the patient are measured prior to re-breathing, during re-breathing, and after re-breathing. A rate of change of carbon dioxide content of the venous blood of the patient is then calculated. The rate of change is then employed in calculating the pulmonary capillary blood flow of the patient.

Growing community of inventors

Hamburg, Germany

Kai Kück

Growing community of inventors

Hamburg, Germany

Kai K&uuml;ck

Kai Kück