Scireq flexivent, User Manual, Page: 22 / 86

20
NAME DESCRIPTION SAMPLE
NPFE
Deep inflation followed by rapid
switch to negative pressure
reservoir (
hardware extension
required
).
Imaging
Pressure-controlled breath-hold,
with or without a preceding deep
inflation with synchronized trigger
signals for imaging modalities such
as Micro-CT or microscopes
(
imaging system not supplied by
SCIREQ , auxiliary hardware
required ).
1.4.3 INDIRECT MEASUREMENT
The
flexiVent
uses the indirect measurement technique to assess respiratory mechanics. In
animal subjects, especially those that do not generate large tidal flows, precise flow
measurement can be quite difficult. Flow measurement difficulty is compounded by signal
losses due to gas compression, so use of flow measurements to calculate mechanics is
technically challenging. The
flexiVent uses measurements of position and pressure, both which
can be measured with great precision and consistency, to calculate mechanics outcomes.
The indirect measurement technique also helps address the technical challenge introduced by
the signal effects of gas compression and cannula resistance. During the inspiratory portion of
ventilation the pressure in the cylinder is slightly higher than that at the airway opening, and the
airway opening pressure is slightly higher than that within the subject’s trachea. Similarly, the