US 7,018,340 B2 · Apparatus and method for non-invasively measuring cardiac output

Abstract

Apparatus and methods for non-invasively determining the cardiac output or pulmonary capillary blood flow of a patient using partial re-breathing techniques. The apparatus includes a substantially instantaneously adjustable deadspace volume for accommodating differences in sizes or breathing capacities of various patients. The apparatus may be constructed of inexpensive elements, including one or more two-way valves, which render the apparatus very simple to use and inexpensive so that the unit may be employed as a disposable product. The method of the invention includes estimating the cardiac output or pulmonary capillary blood flow of a patient based on partial pressure of alveolar CO2, rather than on the partial pressure of end tidal CO2, as previously practiced. A computer program for calculating the cardiac output or pulmonary capillary blood flow of a patient is also disclosed.

Claims17

Dependent claims

A method for estimating the cardiac output of an individual, comprising:

determining a carbon dioxide elimination (VCO2) of the individual for a before re-breathing period and for a during re-breathing period;
calculating a carbon dioxide elimination difference between the carbon dioxide elimination of the before re-breathing period and the carbon dioxide elimination of the during re-breathing period;
estimating a partial pressure of carbon dioxide in alveoli (PACO2) of the individual for the before re-breathing period and for the during re-breathing period based on partial pressure of end tidal carbon dioxide (PetCO2) measurements of the individual during the before re-breathing period and during the during re-breathing period, respectively;
converting each estimation of the partial pressure of carbon dioxide in alveoli to a carbon dioxide content (CCO2);
calculating a carbon dioxide content difference between the carbon dioxide content of the before re-breathing period and the carbon dioxide content of the during re-breathing period;
and
dividing the carbon dioxide elimination difference by the carbon dioxide content difference to estimate cardiac output.

4 more elements

Dependencies are inferred from the claim text.

Apparatus and method for non-invasively measuring cardiac output

Life of this patent

Apparatus and method for non-invasively measuring cardiac output

Life of this patent

Abstract

Claims17