Cardinal Health Alaris 8300 Series, Technical & Service Manual

Page: 28 / 68

PRINCIPLES OF OPERATION
4-2
Alaris ® EtCO
2
Module (8300 Series)
Technical Service Manual
approximately 190 ms and accurate CO
2
readings, even at high respiration rates.
The Microbeam IR source illuminates the
microsample cell and the reference channel.
This proprietary IR light source generates
only the specific wavelengths characteristic
of the CO
2
absorption spectrum. The IR light
that passes through the microsample cell
and the IR light that passes through the
reference channel are measured by IR
detectors.
The microcomputer in the EtCO
2
Module
calculates the CO
2
concentration by
comparing the signals from both channels.
No operator intervention is required for
routine moisture or condensate.
All Microstream ® Disposables contain an
inline hydrophobic filter to extract
condensate and/or patient secretions while
maintaining measurement and waveform
integrity. For humid conditions within the
operating parameters of the EtCO
2
Module
and Microstream ® Disposables, humidity
has no quantitative effect on the CO
2
concentration, given the small 50 mL/min
sample size rate. In high humidity
environments or extended monitoring
periods (24-72 hours) only Microstream
®
Disposables designed for those instances
should be used. In the event of humidity or
condensate outside the EtCO
2
Module’s
operating specifications, the EtCO
2
Module
will present a “Remove Blocked Disposable”
message.
Due to the relatively small sampling size
needed for EtCO
2
readings, partial pressure
does not affect the ability of the EtCO
2
Module to measure EtCO
2
, as long as the
50 mL/min rate can be achieved.
Microstream ® Disposables are single-use,
disposable devices which must be changed
with each use. The manufacturer’s sample
flow, 50 mL/minute, does not affect the
disposable’s life; however, humidity and
specific patient conditions may shorten the
effective life of the disposables.
Microstream
® Disposables are rated for up
to 24 hour and 72 hour use, depending on
the specific Microstream
® Disposable.
The EtCO
2
Module provides readings in
compliance with BTPS (body temperature,
pressure, saturation) standards. There is no
effect on accuracy due to cyclic pressure up
to 10 kPa.
NOTE: BTPS (body temperature, pressure,
saturation assumed 37°C, 47 mmHg)
calculations are made according to:
PCO
2
= FCO
2
X (Pb - 47)
Where:
FCO
2
is the fractional concentration of CO
2
in dry gas, and FCO
2
= % CO
2
/100.
Pb is the ambient pressure.
PCO
2
is the partial pressure of CO
2
at
BTPS.
4.2 GENERAL INFORMATION (Continued)