Cardinal Health Alaris 8000 Series, Directions For Use Manual

Page: 311 / 378

Principle of Operation (Continued)
General Information
5-25
Alaris
®
System Directions for Use
EtCO
2
Module Section
The
50
mL/min sampling flow rate reduces liquid and secretion
accumulation, decreasing the risk of obstruction in the sample
pathway in humid
ICU
environments. The small sample size
eliminates the need for water traps and prevents excess fluid
accumulation.
The
E
t
CO
2
Module draws a gas sample through a
microsample cell (
15
microliters). This extremely small
volume is quickly flushed, allowing for a rise time of
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
E
t
CO
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
E
t
CO
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
E
t
CO
2
Module’s operating specifications, the
E
t
CO
2
Module will present a “Remove Blocked Disposable”
message.
Due to the relatively small sampling size needed for
E
t
CO
2
readings, partial pressure does not affect the ability of the
E
t
CO
2
Module to measure
E
t
CO
2
, as long as the
50
mL/min
rate can be achieved.