Quantification of the degradation products of sevoflurane using four brands of CO2 absorbent in a standard anesthetic circuit.
OBJECTIVE
CO(2) absorbents convert sevoflurane to fluoromethyl-2,2-difluoro-1-(trifluoromethyl) vinyl ether (compound A), whose toxicity in rats raises concern regarding the safety of sevoflurane in a low-flow system. The type of CO(2) absorbent is one of factors that affect compound A concentration in the anesthetic circuit. The aim of the present study was to investigate the concentration of compound A in an anesthetic model circuit following the use of different brands of soda lime and Baralyme.


METHODS
We measured the concentrations of compound A in four different brands of CO(2) absorbent using a low-flow (1 l.min(-1) fresh gas) model circuit in which 2% sevoflurane was circulated. Sodasorb II, Baralyme, Sofnolime and Wakolime-A were used as CO(2) absorbents. The concentration of compound A was measured hourly, and the temperature of the CO(2) absorbent was monitored.


RESULTS
The maximum concentration of compound A in the circuit was highest for Baralyme (25.5 +/- 0.6 ppm) (mean +/- SD), followed by Sodasorb II (18.9 +/- 1.6 ppm), Wakolime-A (16.1 +/- 0.7 ppm), and Sofnolime (15.8 +/- 1.4 ppm). The maximum temperature was 50.8 +/- 1.3 degrees C for Baralyme, 48.8 +/- 1.3 degrees C for Wakolime-A, 47.0 +/- 1.4 degrees C for Sodasorb II, and 43.5 +/- 3.9 degrees C for Sofnolime.


CONCLUSIONS
The relative concentrations of compound A in the low-flow circuit were Baralyme > Sodasorb II > Wakolime-A = Sofnolime.
Ikeuchi
Y
Y
Department of Anesthesiology and Intensive Care, Hamamatsu University School of Medicine, 3600 Handa-cho, Hamamatsu 431-3192, Japan.
Bito
H
H
Katoh
T
T
Sato
S
S