[The use of lithium hydroxide for carbon dioxide absorption prevents formation of compound A during sevoflurane anesthesia].

Unlabelled: Aim of the study was the clinical investigation of sevoflurane degradation when using water-free lithiumhydroxide versus moist Drägersorb 800 for carbon dioxide absorption.

Methods: Concentrations of Compound A in the inspiratory gas mix and serum fluoride levels were measured in two groups of 8 patients each.

Results: When water-free lithiumhydroxide was used for carbon dioxide absorption, concentration of Compound A in the inspiratory gas mix was ca. 1 ppm (near minimal level of detection) as compared to ca. 20 ppm for moist Drägersorb 800. The concentration of fluoride increased during sevoflurane anesthesia (15.0 +/- 4.8 mumol/l with lithiumhydroxide versus 21.9 +/- 4.0 mumol/l with Drägersorb 800 after 60 mins).

Conclusions: When lithiumhydroxide is used, there is only minimal formation of compound A from sevoflurane degradation. Since serum fluoride levels increased in both patient groups, we conclude that this is caused mainly by metabolism of sevoflurane. Capacity of lithiumhydroxide for carbon dioxide absorption is similar to that of Drägersorb 800. Therefore, the use of lithiumhydroxide increases patient safety.