(27) One way to overcome the limitations of conventional capnography for estimation of the PaC[O.sub.2] is volumetric capnography. Conventional devices measure the ETC[O.sub.2] by analyzing the partial pressure of C[O.sub.2] in exhaled air as a function of time.
(30) The following data from McSwain et al demonstrate the relationship between [V.sub.D]/[V.sub.T] measured by volumetric capnography, and the PaC[O.sub.2]-ETC[O.sub.2] gradient (30):
Nevertheless, it would be premature to discard volumetric capnography. The capnograph likely contains information which can be harnessed to refine our ability to predict PaC[O.sub.2].
Estimation of the PaC[O.sub.2] using volumetric capnography and an ANN or similar machine-learning approach.