Production of compound A and carbon monoxide in circle systems : an in vitro comparison of two carbon dioxide absorbents

Two new generation carbon dioxide absorbents, DragerSorb(R) Free and Amsorb(R) Plus, were studied in vitro for formation of compound A or carbon monoxide, during minimal gas flow (500 ml.min(-1)) with sevoflurane or desflurane. Compound A was assessed by gas chromatography/mass spectrometry and carbon monoxide with continuous infrared spectrometry. Fresh and dehydrated absorbents were studied. Mean (SD) time till exhaustion (inspiratory carbon dioxide concentration greater than or equal to 1 kPa) with fresh absorbents was longer with DragerSorb(R) Free (1233 (55) min) than with Amsorb(R) Plus (1025 (55) min; p < 0.01). For both absorbents, values of compound A were < 1 ppm and therefore below clinically significant levels, but were up to 0.25 ppm higher with DragerSorb(R) Free than with Amsorb(R) Plus. Using dehydrated absorbents, values of compound A were about 50% lower than with fresh absorbents and were identical for DragerSorb(R) Free and Amsorb(R) Plus. With dehydrated absorbents, no detectable carbon monoxide was found with desflurane