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. The subject sits at rest for at least 5 minutes'
o The chart recorder is started 30 seconds prior to each exhalation to document baseline pre
exhalation measurements.
o The subject puts on nasal clips 5 seconds prior to each exhalation and exhales by mouth,
and removes the clips between exhalations'
o The subject inhales to total lung capacity then performs a slow vital capacity manoeuvre
to residual volume over 30-60 seconds'
o The exhalations occur 3 minutes apart.
o The subject exhales at a constant mouth pressure of 4mmHg voluntarily controlled by the
subject observing the pressure gauge and keeping it at '10' on the scale'
o The subject exhales at a constant flow at 500mls/min voluntarily controlled by the subject
observing the rotameter, keeping it at '3' on the scale'
o The subject was breathing ambient air when the natural background level of NO was less
than lOPPb.
o The subject continues until 5 exhalations adequate for measurement are made'
For the second set of exhalations:
o The procedure followed the standard set above'
o The subject consumed 60mls of water 20 seconds to 5 seconds prior to the next
exhalation. The water temperature was hot in five subjects and cold for five subjects'
The third set of exhalations was carried out in the standard manner detailed above as for the
first set of exhalations.
7.6.4 Results
The mean peak NO concentrations in the 10 subjects was 93'7ppb (SEM 20'8)' This
decreased by 23ppb (957o CI I2.g, 33.I) to 70.8ppb (sEM 16'5, p-0'002) during the
measuremenrs made with the subjects drinking 60mls of water before each exhalation' There
was then a significant increase of l7ppb (95Vo CI -9.7, -24'l) to 87'8ppb (SEM 18'7' p -
0.001, see Figure ?.9) in the subsequent recordings made in the standard way' The
consumption of water reduced the levels on No obtained regardless of the water temperature'
In the testing with cold water the mean NO went from 76.9ppb to a mean of 57.3ppb, and
then returned to a mean of 72.3ppb in the final set of exhalations. With hot water the mean
NO of 110.5ppb dropped to 84ppb and then returned to 102.8ppb. There was no difference in
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