Appendix
164
EasyOne Pro™ / EasyOne Pro™ LAB
12.10 EasyOne Pro LAB Washout Moment Analysis
The parameters Moment value (M0), Moment ratio 1 (MR1) and Moment
ratio 2 (MR2) are calculated from measured values recorded during the
multi-breath nitrogen washout test. Calculation of these parameters is
defined in a paper published by Shao et al. [17].
Moment Analysis is performed using a standard mathematical technique.
Once Functional residual capacity (FRC) is determined, a dilution number
(
) is assigned to each breath:
k
is defined as the ratio of Cumulated
Expired Volume (CEV) at the end of any breath k to FRC. End-tidal nitrogen
concentrations are normalized and plotted versus dilution number for each
breath, and this distribution is used for Moment Analysis. The normalized
nitrogen concentration A
k
is calculated as C
k
/C
0
, where C
k
is end-tidal
nitrogen concentration at the end of breath k, and C
0
is the end-tidal
nitrogen concentration at the last breath prior to washout.
The following picture shows a diagram of A
k
versus dilution number (
) (see
on page 165 [17]).
In Moment Analysis the r
th
moment can be defined as
Calculation of the Moments requires the integral to be expressed in
discretized form.
Mr
r
A
d
0
=
