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predicted or age, sex and height as defined by the Polgar reference equation (see results in
Section 6.6.4). Two female subjects involved in experiments two and three smoked two
cigarettes per day; the rest were nonsmokers.
The set-up of the analysers and the calibrations before and after each subject doing each set of
exhalations for the individual experiments was carried out in the same manner as described in
Section 6.5.1 .Set up and calibrations' and Section 6.5.2 'The exhalation protocol' of the
previous chapter. Any specific differences from these procedures are documented under the
separate experiments when outlined below. The procedures were written out prior to
performing them, I have therefore re-presented them here using the present tense and
numerical documentation as in the original instructions that I devised'
The results were analysed using the Statistical Products and Services Solutions @ackage 7'0,
SPSS Inc, Chicago, USA). This employs Students t-test for matched pairs' An analysis of
variance for repeated measures was used to determine the effects of flow, mouth pressure, NO
background and pre/post water consumption using the subjects as a blocking variable'
Differences are represented by mean, standard error of the mean (SEM) or 95Vo confidence
intervals (SD) where appropriate. The correlation coefficient for NO levels at the increasing
expiratory flows was calculated for each individual subject and is given for the group as a
whole.
7.3
7.3.1 Hypothesis
1. The levels of NO measured in exhaled air will alter with changes in the expiratory flow.
7.3,2 Aim
1. To compare exhaled NO levels measured at different expiratory flows'
7.3.3 Procedure
Ten adult volunteers (six females) were enrolled. All measurements were made by the t-piece
system. The subjects performed five exhalations at each of four expiratory flows: 25Omls/min'
500mls/min, 75omls/min, and 1lo0mls/min with a final set of measurements at the first flow
to rule out an order effect. Switching the machinery on in advance and calibration between
and after each subject occurred as discussed in the previous chapter (Section 6.5'l)'
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