This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a colleague Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (5) Citing Articles via Google Scholar Google Scholar Articles by Knolle, E. Articles by Gilly, H. Search for Related Content PubMed PubMed Citation Articles by Knolle, E. Articles by Gilly, H.

---

GENERAL ARTICLES

Absorption of Carbon Dioxide by Dry Soda Lime Decreases Carbon Monoxide Formation from Isoflurane Degradation

Erich Knolle, MD^*, and Hermann Gilly, PhD^*,

*Department of Anesthesiology and General Intensive Care (B), University of Vienna; and Ludwig Boltzmann Institute for Experimental Anesthesiology and Research in Intensive Care Medicine, Vienna, Austria

Address correspondence and reprint requests to Erich Knolle, MD, Department of Anesthesiology and General Intensive Care (B), University of Vienna, Waehringer Guertel 18–20, A-1090 Vienna, Austria. Address e-mail to erich.knolle{at}univie.ac.at

This study was performed to determine whether the absorption of carbon dioxide (CO₂) influences the formation of carbon monoxide (CO) from degradation of isoflurane in dry soda lime. Isoflurane (0.5%), CO₂ (5%), a combination of the two in oxygen, and pure oxygen were separately passed through samples of 600 g of completely dried soda lime (duration of exposure, 60 min; flow rate, 5 L/min). Downstream of the soda lime, we measured concentrations of CO, isoflurane, and CO₂ as well as the gas temperature. CO₂ increased the peaks of CO concentration (842 ± 81 vs 738 ± 28 ppm) and shortened the rise time of CO to maximum values (12 ± 2 vs 19 ± 4 min). However, CO₂ inhibited total CO formation (99 ± 10 vs 145 ± 6 mL). At the same time, CO₂ absorption by the soda lime decreased in the presence of CO formation (from 21.4 ± 0.8 to 19.4 ± 0.9 g). The temperature of the gases increased during the passage of both isoflurane and CO₂ (to 32.6 ± 2.0°C and 39.4 ± 4.0°C, respectively), but the largest increase (to 41.5 ± 2.1°C) was recorded when isoflurane and CO₂ simultaneously passed through the dry soda lime. We assume that the simultaneous reduction in CO formation and CO₂ absorption is caused by the competition for the alkali hydroxides present in most of soda lime brands.

Implications: We determined, in vitro, that carbon monoxide (CO) formation from isoflurane by dry soda lime is reduced by carbon dioxide (CO₂). We believe that the potential for injury from CO is less in the clinical milieu than suggested by data from experiments without CO₂ because of an interdependence between CO formation and CO₂ absorption.

This article has been cited by other articles:

				M. J. Laster and E. I. Eger II Temperatures in Soda Lime During Degradation of Desflurane, Isoflurane, and Sevoflurane by Desiccated Soda Lime Anesth. Analg., September 1, 2005; 101(3): 753 - 757. [Abstract] [Full Text] [PDF]

				E. Knolle, G. Heinze, and H. Gilly Carbon Monoxide Formation in Dry Soda Lime is Prolonged at Low Gas Flow Anesth. Analg., August 1, 2001; 93(2): 488 - 493. [Abstract] [Full Text] [PDF]

				H. Higuchi, Y. Adachi, S. Arimura, M. Kanno, and T. Satoh The Carbon Dioxide Absorption Capacity of Amsorb(R) is Half That of Soda Lime Anesth. Analg., July 1, 2001; 93(1): 221 - 225. [Abstract] [Full Text] [PDF]