Anesthetic Gases; Gasses That Induce Reading Error - Teledyne TED 200-T Instruction Manual

When monitoring for oxygen in breathing circuits, the diverter must be used. The
diverter should be screwed onto the threaded front end of the T-7 sensor. A tee adapter
(either plastic, P/N A268, or metal, P/N A283) should be placed into the circuit, and the
above sensor assembly plugged into the tee adapter.
CAUTION: Check the breathing circuit for leaks. Be certain that the
circuit downstream of the sensor does not produce any
back-pressure or restriction to flow, or errors in readings will
result.
When monitoring for oxygen in confined volumes such as incubators, hoods, etc.,
the flow diverter must be removed from the T-7 sensor so that it does not interfere with
the rapid exchange of gases to and from the sensing surface of the T-7.
CAUTION: Failure to remove the diverter in these application areas will
result in a marked lowering of the response time of the sen-
sor.
The T-7 sensor can be placed or hung inside incubators, tents, etc. When it is
necessary to thread the cable through a small hole in order to gain access to the inside of
a chamber, the cable should be disconnected at the sensor, threaded through the hole,
and reconnected inside the chamber.
A calibration check may be conducted at any time to assure proper operation.
Remove the diverter and expose the sensor to room air, and verify that the reading is
20–22%. Expose the sensor to 100% oxygen (preferably using the diverter and tee
adapter in a flowing circuit) and verify that the reading is 99–101%.

2.2.2 Anesthetic Gases

2.2.2.1 Gases that induce reading error
When using the T-7 sensor in the presence of anesthetic gases such as Halothane,
the oxygen reading may fall (see the table below). The magnitude of this error will
depend upon the level of oxygen and the duration of exposure.
The anesthetic agents listed in the following table (Halothane, Enflurane,
Isoflurane, Sevoflurane, and Desflurane) were vaporized into a stream of 30% oxygen/
70% nitrous oxide, and the resulting drops in oxygen level after an exposure of approxi-
mately two hours were noted.
Exposures in excess of two hours will produce slightly greater error. The errors
listed are typical for all oxygen sensors such as the T-7. Exposing the sensor to air or
gases that do not contain anesthetic agents for a period of time equal to or greater than
the exposure interval will eliminate the reading error in most cases.
Teledyne Analytical Instruments
Operations 2
2-7