GE Analytical Instruments ©2006 9-2 DLM 14291 Rev. A
Figure 9- 2: Setup for Breath-by-
Breath Measurement on Ventilated
sampling of inspired and expired gas. The NOA exhalation pressure transducer is
used to determine the beginning and end of exhalation using the NOAnalysis
Breath program.
Ventilated Subjects
An ET tube adapter equipped with a
female Luer sampling port is installed
between the ventilator Y-piece and the
ET tube. For small animals, an adapter
with a female Luer port is positioned
between the ventilator Y-piece and the
tracheal cannula. A three-way Luer
stopcock is suitable and provides a
means to isolate the sampling port while
continuing to ventilate the animal. A
Luer tee is used to connect the NO sampling and pressure lines to the circuit. Since
the NOA using the standard frit restrictor is drawing 200 mL/min of gas from the
circuit, the ventilator must be set so that the product of minute ventilation times
tidal volume is greater than 200 mL/min. Lower flow frit restrictors can be used if
the ventilator cannot be adjusted to provide > 200 mL/min of gas.
The inspired gas must be low in nitric oxide, preferably <1 ppb. In most cases,
ambient air cannot be used and hospital air may contain high levels of NO. The
best sources are compressed gas cylinders of air or oxygen that are known to be
low in NO. In some cases, the gas can be connected directly to the ventilator or
for piston-type ventilators, a reservoir can be filled with low NO gas and
connected to the inlet of the ventilator.
The NOAnalysis Breath program detects the beginning and end of exhalations
based on changes in the exhalation pressure and reports maximum, minimum and
end-tidal NO values for each breath.
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