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LETTERS

Composition of CO₂ Absorbents

Department of AnesthesiaStanford University School of MedicineStanford, CA

To The Editor:

The June, July, and August 2000 issues of Anesthesia & Analgesia contain articles (1–3) that deal with CO₂ absorbents and their differing ability to cause breakdown of inhaled anesthetics, i.e., sevoflurane to Compound A and desflurane to CO. The articles examined a number of absorbents including two different ones with similar names, the older Drägersorb 800 and the more recent Drägersorb 800Plus (Drager, Telford, PA, Lübeck, Germany).

Unfortunately, the articles disagree in the composition of these absorbents and the breakdown of anesthetic agents that they cause, as noted below.

Stabernack (1) et al. reported they studied Dragersorb 800, (North American Drager, Telford, PA) and stated that it contained 3% NaOH and 0% KOH. High levels of CO and Compound A were produced.

Higuchi et al. (2) reported they too studied Drägersorb 800 (Dräger, Lübeck, Germany) which they stated contained 2% NaOH and 3% KOH; high levels of Compound A were produced. They also studied Drägersorb 800Plus which they stated contained 2% NaOH and 0.003% KOH; very low levels of Compound A were produced.

Yamakage et al. (3) reported they studied Drägersorb 800Plus (Dräger, Lübeck, Germany) which they stated contained 2% NaOH and 3% KOH; high levels of Compound A were produced.

At the very least, there appears to be an error in identifying the KOH composition of Drägersorb 800 and Drägersorb 800Plus in one or several of these articles that the authors should clarify. The discrepancies additionally raise a number of questions. What is the composition of Drägersorb 800 and Drägersorb 800Plus? Which CO₂ absorbents actually were studied by the three groups of investigators? Does Dragersorb 800 distributed by North American Drager (now called Draeger Medical, Telford, PA) differ from that distributed by Dräger, Lübeck, Germany? What is the role of KOH in the breakdown of sevoflurane and desflurane? Draeger Medical’s material safety data sheet states that Drägersorb 800Plus contains 1%–3% NaOH and no KOH; they no longer distribute Drägersorb 800 and the material safety data sheet was not available. Of interest, all three groups of investigators studied the novel CO₂ absorbent Amsorb (Armstrong Medical, Londonderry, UK), which contains neither NaOH nor KOH. They were in agreement that Amsorb did not cause degradation of sevoflurane or desflurane (1–3).

References

88145. Stabernack CR, Brown R, Laster MJ, et al. Absorbents differ enormously in their capacity to produce compound A and carbon monoxide. Anesth Analg 2000; 90: 1428–35.[Abstract/Free Full Text]
88145. Yamakage M, Yamada S, Chen X, et al. Carbon dioxide absorbents containing potassium hydroxide produce much larger concentrations of Compound A from sevoflurane in clinical practice. Anesth Analg 2000; 91: 220–4.[Abstract/Free Full Text]
88145. Higuchi H, Adachi Y, Arimura S, et al. Compound A concentrations during low-flow sevoflurane anesthesia correlate directly with the concentration of monovalent bases in carbon dioxide absorbents. Anesth Analg 2000; 91: 434–9.[Abstract/Free Full Text]

Response

Department of AnesthesiaSelf Defence Force Central HospitalTokyo, Japan

In Response:

We thank Dr. Mazze for his interest in our article (1). According to Miss Konno, assistant manager, Tokyo Sales Department, Dräger Japan (Tokyo, Japan), Dräger (Luebeck, Germany) changed the old CO₂ absorbent, "Drägersorb 800" to a new absorbent "Drägersorb 800 plus" in 1999 all over the world. As indicated in our article (1) and Dräger Medical’s material safety data sheet, Drägersorb 800 contains some NaOH (1%–2%) and KOH (2%–3%), whereas Drägersorb 800 plus contains some NaOH (1%–2%) and only trace amounts of KOH (0.003%). We prepared these old and new CO₂ absorbents in our study and measured Compound A concentrations under low-flow sevoflurane anesthesia using four absorbents, including Drägersorb 800 and Drägersorb 800 plus (1).

We were also surprised by the results of Stabernack et al. (2), because it has long been thought that KOH has a greater involvement than NaOH in the production of Compound A (3). Considering the results obtained by Stabernack et al. (2), the difference in the production of Compound A among the absorbents cannot be explained by base composition. Factors other than base composition might be involved. In any event, all studies were in agreement in that Amsorb (Armstrong Medical Ltd., Londonderry, UK) did not cause the degradation of sevoflurane (1,2,4,5).

Footnotes

Note: Drs. Eger and Yamakage chose not to respond.

References

88146. Higuchi H, Adachi Y, Arimura S, et al. Compound A concentrations during low-flow sevoflurane anesthesia correlate directly with the concentration of monovalent bases in carbon dioxide absorbents. Anesth Analg 2000; 91: 434–9.
88146. Stabernack CR, Brown R, Laster MJ, et al. Absorbents differ enormously in their capacity to produce compound A and carbon monoxide. Anesth Analg 2000; 90: 1428–35.
88146. Neumann M, Laster M, Weiskopf R, et al. The elimination of sodium and potassium hydroxides from desiccated soda lime diminishes degradation of desflurane to carbon monoxide and sevoflurane to compound A but does not compromise carbon dioxide absorption. Anesth Analg 1999; 89: 768–73.[Abstract/Free Full Text]
88146. Murray JM, Renfrew CW, Bedi A, et al. Amsorb: a new carbon dioxide absorbent for use in anesthetic breathing systems. Anesthesiology 1999; 91: 1342–8.[Web of Science][Medline]
88146. Yamakage M, Yamada S, Chen X, et al. Carbon dioxide absorbents containing potassium hydroxide produce much larger concentrations of compound A from sevoflurane in clinical practice. Anesth Analg 2000; 91: 220–4.

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