Descriptions
Safety features of gas supply
Notes for reducing condensation
136
Safety features of gas supply
N
2
O lock and AIR changeover
If the O
2
supply fails during operation,
– the O
2
shortage signal sounds (pneumatic whistle),
– delivery of N
2
O is stopped and
– «
AIR
« is automatically activated on the bank of
measuring tubes, although the control lever is still
set to »
N
2
O
«.
Resumption of the O
2
supply pressure is detected by the
machine and the former status is restored automatically.
Drive gas changeover
Approx. 2 L/min drive gas are required for the ventilator
and approx. 12 L/min for the secretion aspirator. This
gas is normally drawn from the compressed air supply.
If it is not available or has failed, the machine automatic-
ally switches over to the O
2
supply and draws its drive
gas from there.
Notes for reducing condensation
Water vapour is liberated when CO
2
is absorbed by the
soda lime.
The greater the proportion of rebreathed gas (low-flow
technique), the more moisture is produced.
Cato has been optimized for this low-flow technique:
– The electric heating prevents condensation forming
in the breathing system.
– A large water trough has been integrated into the
base of the absorber pot to collect condensation.
– The large cross-sections of the gas lines and valves
reduce the risk of condensation impairing their
functioning.
The following points should be noted when carrying
out low-flow anaesthesia in practice, particularly during
extensive surgery and at low room temperatures.
●
Hoses should be routed so that condensation can
collect at the lowest point and cannot flow back to the
patient or to the breathing system.
Condensation must be drained from the hoses at
regular intervals.
●
Water traps should be used for surgery lasting more
than 1.5 hours. They must be positioned at the lowest
point in the system so that the condensation can flow
into the water traps.
Water traps must be drained regularly.
Pressure and flow measurement may be impaired if
condensation flows into the breathing system.
●
The breathing system must be replaced by a dry one
in such cases.
●
The microbial filter must be protected against
condensation. Although insensitive to moisture,
condensation will increase the resistance in the
microbial filter!
The microbial filter must then be replaced.
If condensation collects in the pressure measuring line:
●
Replace the pressure measuring line and its filter.
●
Install the T-piece and filter for the sampling hose with
the connection pointing upwards.
A new T-piece must be fitted after every patient.
●
Install the Y-piece with Luer-Lock connection,
measuring port pointing upwards.
If microbial filters are used in the breathing system,
the Y-piece and hoses must be replaced after every
patient.
If microbial filters are used in the Y-piece:
the Y-piece and hoses must be replaced every day.
●
The sampling hose must be replaced if there are
droplets of condensation in the hose.
Recommendation
If condensation is to be expected:
●
Replace the breathing system and piston cylinder unit
every day.
●
Replace the soda lime every day.
If the breathing system and piston cylinder unit cannot be
replaced every day:
●
Drain the condensation frequently with the aid of a
disinfectant.
●
Leave the breathing system and piston cylinder unit
open for a few hours so that they can dry.