A new CO2 absorbent, Amsorb® (A), which does not contain monovalent bases, is ideal because it does not degrade volatile anesthetics to either Compound A (from sevoflurane) or carbon monoxide (from desflurane, enflurane, or isoflurane). The CO2 absorption capacity of A, however, has not been investigated under clinical conditions. In this study, we compared the longevity (time to exhaustion) and CO2 absorption capacity (the volume of CO2 absorbed before CO2 rebreathing occurs) of A under low-flow anesthesia (1 L/min) with those of two soda lime absorbents—Medisorb® (M) and Sodasorb® (S)—by using a 750-mL ADU canister and a 1350-mL Aestiva 3000 canister. In the study with the ADU canister, the longevity of A was 213 ± 71 min, significantly less than those of M (445 ± 125;P < 0.01) and S (503 ± 89;P < 0.001). The CO2 absorption capacity (L/100 g absorbent) of A was 5.5 ± 1.2, significantly less than those of M (10.7 ± 1.7) and S (12.1 ± 1.8;P < 0.001). In the study with the Aestiva 3000 canister, the longevity of A was 218 ± 61 min, significantly less than those of M (538 ± 136) and S (528 ± 103;P < 0.001). The CO2 absorption capacity (L/100 g absorbent) of A was 7.6 ± 1.6, significantly less than those of M (14.4 ± 1.8) and S (14.8 ± 2.3;P < 0.001). These results indicate that the CO2 absorption capacity of A is half that of M or S and that the difference in the CO2 absorption capacity between A and M or S is almost constant, regardless of the canister design.
*Department of Anesthesia, Self Defense Force Central Hospital, Tokyo, Japan; and †Department of Anesthesiology, National Defense Medical College, Saitama, Japan
February 21, 2001.
Address correspondence and reprint requests to Hideyuki Higuchi, MD, Department of Anesthesia, Self Defense Force Hanshin Hospital, 4-1-50 Kushiro, Kawanishi, Hyogo 666-0024, Japan. Address e-mail to firstname.lastname@example.org.