Siemens Drager medical Carina, Instructions For Use Manual, Page: 139 / 144

Instructions for Use Carina SW 3.n
139
Description
Volume measurement
VTi (hose system with leak valve)
VTi value displayed on the screen is the volume of
air delivered to the patient’s lungs (not in
SPN-CPAP).
VTi = total delivered volume – intentional leakage
from leakage valve – additional leakage
Additional leakage is compensated by the device.
Automatic leakage compensation require some
breaths to display the connected VT value.
VT (hose system with expiratory valve)
VT value displayed on the screen is the volume of
air delivered by Carina without any leakage com-
pensation (not in SPN-CPAP).
VT = total delivered volume
MVi (hose system with leak valve)
MVi value displayed on the screen is the averaged
volume of air delivered to patient lungs.
MVi = total delivered volume – intentional leakage
from leakage valve – additional leakage
Additional leakage is compensated by the device.
Automatic leakage compensation require some
breaths to display the corrected MV value.
MV (hose system with expiratory valve)
MV value displayed on the screen is the averaged
volume of air delivered by Carina without any leak-
age compensation.
MV = total delivered volume
MV
leak
(hose system with leak valve)
With a mask, breathing gas will frequently dis-
charge to ambient air around mask. The Carina
flow sensor is located inside the device near the
inspiratory connection. During inspiration time,
breathing gas will be lost after measurement at
inspiratory side in the device. During expiration
time, it will be lost before being measured.
Therefore, tidal volume measured for inspiration
(total delivered flow) will be larger than true tidal
volume (air delivered to the lung), tidal volume for
expiration will be smaller than total delivered flow.
On average, the difference between inspiratory (air
delivered to the lung) and expiratory flow is equal.
The gas volume that did not flow back through the
sensor must have escaped through the leak.
Volume accuracy in case of leakages
Due to Carina's limited monitoring functionality (no
internal monitoring of expiratory minute volume),
Carina is not always able to accurately determine
the amount of leakage. In volume guarantee mode
(SPN-PS VG) and in volume control mode
(VC-SIMV), the accuracy of the displayed values
VTi and MVi and the actual tidal volume, as speci-
fied in the chapter "Technical Data", can only be
guaranteed if there are no leakages. This behavior
is independent of the application method (mask or
tube) used.
CAUTION
Before making clinical decisions based on the VTi
and MVi values displayed by Carina, make sure
that no leakages impair the measurement.