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NO and COz results from single exhalations as the mean of five recordings in twelve adult subjects by
direct or t-piece system measurements (m = mdle, f = female). (a. NO measured in parts per billion. b.
CO2 measured as % of totalgas expired).
There was no significant difference between peerk COz level by the direct measurements with
a mean of 5.8l%o (range 4.0Vo to 6.9Vo) or t-piece measurements with a mean of 6.l9Vo (range
4.4-7.2Vo, p = 0.66) or between male and female subjects (5.84Vo venius 5.75Vo direct, p =
0.64, and 6.4l%o versus 6.03Vo t-piece, p = 0.44), (see Figure 6.8). There was no difference in
repeated last set of exhalations for either NO or COz whether it was a repetition of the direct
or the t-piece measurements, although the coefficient of variation had improved suggesting
that there may be some improvement with training.
Figure 6.8: Mean exhaled COz levels measured by direct and t-piece systems
Comparisons of mean exhaled peak CO2 by the direct and t-piece system (n--12, each mean of 5
exhalations, SEM = standard error of the mean).
6.6.4 (ii) Peak nitric oxide versus area under the nitric oxide curve
The correlation coefficients comparing the results of peak NO level versus using area under
the curve for these traces were 0.87 for the direct results and 0.81 for the t-piece results and
are shown below in Figure 6.9.
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