Dräger Medical Narkomed GS, Operator'S Instruction Manual

Page: 142 / 204

14-2 Narkomed GS Operator’s Instruction Manual Draeger Medical, Inc.
14
Breathing Pressure Monitoring
Overview
Breathing pressure is measured with a solid-state pressure transducer
that can sense pressure at either the absorber or patient Y-piece,
depending on which pilot line is used.
Choice of Breathing Pressure Monitoring Location
Draeger Medical has no control over the type of breathing hoses and Y-
pieces that are ultimately used with Draeger Medical absorber systems
and pressure monitors—specifically, whether such user-supplied
components include a terminal for pressure monitoring at or near the Y-
piece. In order to ensure that some form of pressure monitoring is always
used, provisions have been made for pressure monitoring at the absorber
(the quick-connect fitting on the absorber gas pipe). However, do not
construe this provision for monitoring at the absorber as a
recommendation from Draeger Medical for this pressure monitoring
location.
In fact, arguments can be made for pressure monitoring at either the
Y-piece or at the absorber. Advocates of Y-piece pressure monitoring first
claim that it more accurately reflects the pressure developed in the
patient's lungs. They also claim that a blocked breathing system can be
more easily detected with this method when compared with pressure
monitoring at the absorber.
For example, if the inspiratory breathing hose became kinked or blocked
during automatic ventilation, the ventilator bellows would continue to
cycle against the blocked hose. A pressure monitor connected at the Y-piece
(downstream of the occlusion) could sense either an absence of pressure
fluctuation and alarm, or could sense a reduced pressure fluctuation
(below the threshold pressure alarm limit) and alarm. In contrast, a
pressure monitor connected at the absorber (upstream of the occlusion)
could sense a pressure fluctuation above the threshold pressure alarm
limit, and thus would not alarm. (Both of these scenarios assume that the
occlusion does not cause a peak pressure high enough to activate the peak
pressure alarm, which is meant to detect pressures likely to cause
barotrauma.)
However, Draeger Medical disagrees with the idea of relying on pressure
monitoring to detect a blocked breathing circuit. Carbon dioxide
monitoring and respiratory flow monitoring provide superior detection of
blocked breathing paths when compared to pressure monitoring, which
detects such conditions only in some instances. Draeger Medical pressure
monitors are therefore not promoted for detection of blocked breathing
paths.
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