Apparatus and methods for non-invasively determining cardiac output using
partial re-breathing techniques are disclosed in which the apparatus is constructed
with an instantaneously adjustable deadspace for accommodating differences in breathing
capacities of various patients. The apparatus is constructed of inexpensive elements,
including a single two-way valve which renders the apparatus very simple to use
and inexpensive so that the unit may be readily disposable. The method of the invention
provides a novel means of estimating cardiac output based on alveolar CO2
values rather than end-tidal CO2 values as previously practiced. A program
for calculating cardiac output is also disclosed.
