ANESTHESIA & ANALGESIA - IARS

ANESTH ANALG ABSTRACTS
2004; 98; S-1–S-282
S-86
FACTORS AFFECTING THE CONCENTRATION OF CO IN
THE BREATHING CIRCUIT AND THE CONCENTRATION
OF ARTERIAL COHB DURING LOW-FLOW ISOFLURANE
ANESTHESIA IN SMOKING AND NON-SMOKING
SUBJECTS
AUTHORS: M. Yamakage, S. Yoshida, S. Iwasaki, M. Mizuuchi,
A. Namiki;
AFFILIATION: Sapporo Medical University School of Medicine,
Sapporo, Japan.
INTRODUCTION: Smokers have a high incidence of postoperative
respiratory complications, and smoking can also increase the
concentration of carboxyhemoglobin (COHb) up to 5%~10%, leading
to cardiac events during anesthesia. Carbon monoxide (CO) can be
produced from degradation of isoflurane by soda lime, especially with
dry soda lime or by the use of a low-flow anesthetic technique. Some
carbon dioxide (CO2) absorbents that contain few or no strong bases
have become available for clinical use. We investigated the
concentration of CO in the anesthetic circuit and the concentration of
arterial COHb during low-flow isoflurane anesthesia in smoking and
non-smoking subjects using various kinds of CO2 absorbents with and
without strong bases.
METHODS: Sixty ASA physical status I or II adult patients were
enrolled in this study. Thirty patients who were smoking up to the
operating date and 30 patients who had never smoked were selected as
smoker group and non-smoker group, respectively. Anesthesia was
maintained with isoflurane and nitrous oxide (1 L/min)/oxygen (1 L/
min). Ventilation was controlled to maintain end-tidal partial pressure
of CO2 between 34 and 38 mmHg. The end-tidal isoflurane
concentrations were adjusted to 1.0%. Each group (smoker or nonsmoker
group) randomly divided into three groups according to the type
of CO2 absorbent used. The CO2 absorbents used were Wakolime A,
Dragersorb Free, and Amsorb. Gas samples for measurement of CO
(Carbolyzer, mBA-2000) were obtained from the inspiratory limb of the
circle system at 0, 1, 2, 3, and 4 hrs after exposure to isoflurane.
Concentrations of arterial COHb were measured at the same time as the
S-87
8500 POET ® IQ -AN ACCURATE ANESTHESIA GAS
MONITOR?
AUTHORS: P. R. Lichtenthal, R. G. Loeb, S. E. Morgan;
AFFILIATION: University of Arizona, Tucson, AZ.
INTRODUCTION: While many companies sell respiratory gas
monitors, most of these are OEM; only a few companies manufacture
gas monitor benches. Criticare Systems, Inc., a longtime manufacturer
of gas analyzer benches, recently released a new product, the 8500
Poet ® IQ. This sidestream analyzer uses non-dispersive infrared (NDIR)
technology to identify and measure CO2, N2O and five halogenated
anesthetics, and a fast polarographic cell to measure O2 . The object of
this study was to determine the accuracy and stability of this new
respiratory gas analyzer as compared to an industry-standard analyzer
(Datex AS3).
METHODS: For a period of four weeks we conducted daily quality
checks on both gas analyzers. Each was calibrated prior to the study by
a factory-authorized technician . The analyzers were used clinically
during the study period; they were located in the same operating room,
and were used simultaneously for every case. Both analyzers were
tested every morning for their ability to correctly analyze a series of 9
precision gas mixtures (Scott Medical Products), each of which
contained CO2. The analyzer sample lines were connected to computercontrolled
solenoid valves that simulated respiratory rates of 10, 30, 60
breaths per minute by switching the inflow path between test gas and
room air every 3, 1, or 0.5 second, respectively. Stable end-tidal values
were recorded from each analyzer’s display. Data from both analyzers
for each of the 9 gases at 3 respiratory rates were collected. The average
of the daily readings during the study (mean), day-to-day variation
(SD), and the average error (bias) were then calculated.
RESULTS:
Both analyzers had stable readings over the 4-week course of the
study (day to day standard deviation