C-8 624074/07
CASV
®
(Adaptive Support Ventilation)
• A bacterial filter or an HME can require compensation. The
volume of these devices, for an adult, is on average 50 to
60 ml, but may be as high as 95 ml (Mallinckrodt
Hygroster). For an HME, a simple rule of thumb is to add
10% to the IBW (by adjusting the Patient height control).
Step 4: Adjusting ventilation: Maintaining adequate
ventilation
WARNING
It is inappropriate to adjust the IBW (through the
Patient height control) to change minute volume.
Always use the %MinVol control to adjust minute
volume.
After ASV is started, the device calculates an optimal breath
pattern and associated target values for tidal volume and rate
according to the rules in Section C.4. ASV then adjusts the
inspiratory pressure (Pinsp) and machine rate (fControl) to
achieve the targets.
After the calculated targets are reached, the result of the
ventilation needs to be assessed. All the device’s monitored
parameters can be used for this purpose. However, to assess
respiratory acid-base status, it is recommended that arterial
blood gases be measured and minute ventilation be adjusted
accordingly. Table C-1 provides examples of how to adjust the
%MinVol setting.
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