Heyer iTernIS ADV, Operator'S Manual

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7. 8
• DIAMETER: 4 – 12 mm (depending on the type of patient).
• COMPENSATE: compensation percentage, adjustable between 10% and 100%
with 50% as default value.
• ACTIVATED: YES or NO. It enables the compensations. If the NO option is selec -
ted and it is later accepted, the configuration of the previous parameters is saved
in the memory.
Lastly, the cursor must be placed on the Accept button and the dial must be pres-
sed to confirm the changes.
Fig. 7-6
TUBE COMPEN -
SATION window.
The purpose of the
Tube compensation
is to get the tracheal pressure to stay equal
to the pressure configured by the operator (PCV or PSV). To that effect, the ventila -
tor adjusts the pressure in the patient circuit to compensate for the drop in pressure
throughout the tube. To achieve this, it is necessary to generate a pressure in the
patient circuit higher than the configured one, whose magnitude is calculated ac -
cording to the following equations:
• P
tracheal
= Configured pressure (PCV o PSV)  P
aw
> P
tracheal
• P
aw
= P
tracheal
+ P
comp
 P
tracheal
= P
aw
- P
comp
• P
comp
= K
●
Flow
2
●
(compensation %)
Where:
• P
comp
is the pressure level added to the pressure in the circuit (P
aw
) to compensate
for the resistance of the tube.
•
K
is a coefficient derived from the resistive characteristics of the tube. This coeffi -
cient depends on the diameter and the characteristics of the tube used.
• The Flow in the equation is the flow of gases that the ventilator drives to generate
the configured pressure.
When the
Tube compensation
is activated, it will be possible to observe a superimpo-
sed white curve on the pressure/time graph (and on the pressure/volume loop) that
corresponds to the calculated tracheal pressure. Depending on the flow provided or
required and the compensation percentage, it will be possible to see that the airway