Dräger Babylog VN500 Instructions For Use Manual page 258

Description
When tube compensation is activated, the ventila-
tion pressure in the breathing circuit is increased
during inspiration or decreased during expiration.
The airway pressure is adjusted to the tracheal lev-
el if 100 % compensation of the tube resistance has
been selected.
Expiratory tube compensation can be deactivated.
For the mandatory portion of the breath, inspiratory
tube compensation can be deactivated.
When tube compensation is activated,
Babylog VN500 controls the ventilation pressure so
that the resistive work of breathing on the tube is
compensated in accordance with the selected de-
gree of compensation.
Depending on the direction of the patient flow, the
airway pressure is increased during inspiration or
decreased during expiration.
The airway pressure can be reduced to a minimum
of 0 mbar (0 cmH O).
2
The maximum value for the airway pressure can be
set using the Pmax therapy control. If Pmax is not
linked to the alarm limit Paw high, the maximum
pressure is limited to 5 mbar (5 cmH
Paw high alarm limit. The pressure limitation mes-
sage is displayed when the maximum permitted
values are reached.
If the value selected for Paw high or Pmax is too
low, it may impair the effectiveness of tube compen-
sation. If the value selected for Paw high or Pmax
is too high, it may result in unwanted high airway
pressures. When setting Pmax, be aware that this
value may actually be reached in contrast to the
value for Paw high.
258
Calculating the support
The level of support ΔPaw applied during ATC is
calculated on the basis of a square function of tube
resistance and patient flow.
ΔPaw =
Comp.:
K
Tube:
Flow:
Tube coefficient
The tube coefficient K
the basis of the results obtained by Guttmann et al*.
The tube coefficient K
always taken as the basis. The effect of the short-
ened length is negligible.
The values for the tube coefficients are shown in
the following tables.
O) below the
2
* Literature reference [5], see page 276
Instructions for Use Infinity Acute Care System – Babylog VN500 SW 2.n
2
Comp. x K x Flow
Tube
Degree of compensation 0 to 100 %
Tube coefficient (see table on page 259)
Patient flow
is largely determined on
Tube
for the full-length tube is
Tube