GE Analytical Instruments ©2006 8-15 DLM 14291 Rev. A
Figure 8-6: Pressure Flow Calibration for Bag Kits.
The exhalation pressures reported above permit collection of exhaled NO at a flow
rate of 350 mL/s for the Vital Capacity and 50 mL/s for the Deadspace Discard bag
kits. Figure 8-6 shows the exhalation flow as a function of pressure for the two kits
from 5 to 25 cm H
2
O along with logarithmic curve fit of the data. For the Vital
Capacity bag kit, flows ranging from 200 to 475 mL/s are obtained over this
pressure ranges. For the Deadspace Discard kit, flows range from 50 to 125 mL/s
for these pressures.
Stability of NO in Mylar Bags
It is best to analyze the samples as soon after collection as possible. In the ATS
guidelines it is reported that the concentration of NO in new Mylar bags is stable
for up to 48 hours (Massaro et. al., Am. J. Respir. Crit Care Med 1995, 152, 800-
803). Sievers testing has shown that NO concentrations slowly increases over time
with a small but significant increase (1-2 ppb) observed after 8-12 hours. This
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