Vol. 86, Issue 2, 647-650, February 1999
Infrared CO2 analyzer
error: an effect of background gas
(N2 and
O2)
R.
Arieli,
O.
Ertracht, and
Y.
Daskalovic
Israel Naval Medical Institute, Israel Defense Forces Medical Corps,
Haifa 31080, Israel
Three
infrared CO2 analyzers were tested
for the effect of background gases: the Ametek CD-3A (Ametek, Thermox
Instruments Division, Pittsburgh, PA), the Dräger Multiwarn P
CO2 (Dräger, Lübeck,
Germany), and the Servomex 1440 (Servomex, Crowborough, East Sussex,
UK). Various CO2 concentrations
were prepared with Wösthoff precision pumps (H. Wösthoff,
Bochum, Germany). Calibration with a different background gas
(O2 or
N2) caused a similar but systematic error in the CO2
readings of all three analyzers. When the
CO2 analyzers were calibrated with
N2 as the background gas, the
CO2 reading in an
O2-enriched atmosphere was 8%
lower than the true value. Conversely, calibration with
O2 as the background gas resulted
in a 10% overestimation of CO2
levels when N2 was the background
gas. This error may be important in a few fields of respiratory physiology.
carbon dioxide calibration; hyperoxia; alveolar-arterial
difference
