Physical factors affecting the production of carbon monoxide from anesthetic breakdown. Anesthesiology 2001 Mar;94(3):453-6
Date
05/26/2001Pubmed ID
11374605DOI
10.1097/00000542-200103000-00015Scopus ID
2-s2.0-0035096084 (requires institutional sign-in at Scopus site) 21 CitationsAbstract
BACKGROUND: Parameters determining carbon monoxide (CO) concentrations produced by anesthetic breakdown have not been adequately studied in clinical situations. The authors hypothesized that these data will identify modifiable risk factors.
METHODS: Carbon monoxide concentrations were measured when partially desiccated barium hydroxide lime was reacted with isoflurane (1.5%) and desflurane (7.5%) in a Draeger Narkomed 2 anesthesia machine with a latex breathing bag substituting for a patient. Additional experiments determined the effects of carbon dioxide (0 or 350 ml/min), fresh gas flow rates (1 or 4 l/min), minute ventilation (6 or 18 l/min), or absorbent quantity (1 or 2 canisters). End-tidal anesthetic concentrations were adjusted according to a monochromatic infrared monitor.
RESULTS: Desflurane produced approximately 20 times more CO than isoflurane when completely dried absorbents were used. Peak CO concentrations approached 100,000 ppm with desflurane. Traces of water remaining after a 66-h drying time (one weekend) markedly reduced the generation of CO compared with 2 weeks of drying. Reducing the quantity of desiccated absorbent by 50% reduced the total CO production by 40% in the first hour. Increasing the fresh gas flow rate from 1 to 4 l/min increased CO production by 67% in the first hour but simultaneously decreased average inspiratory concentrations by 53%. Carbon dioxide decreased CO production by 12% in completely desiccated absorbents.
CONCLUSION: Anesthetic identity, fresh gas flow rates, absorbent quantity, and water content are the most important factors determining patient exposures. Minute ventilation and carbon dioxide production by the patient are relatively unimportant.
Author List
Woehlck HJ, Dunning M 3rd, Raza T, Ruiz F, Bolla B, Zink WAuthors
Franklin J. Ruiz MD Assistant Professor in the Anesthesiology department at Medical College of WisconsinHarvey J. Woehlck MD Professor in the Anesthesiology department at Medical College of Wisconsin
MESH terms used to index this publication - Major topics in bold
AbsorptionAnesthesia, Inhalation
Anesthetics, Inhalation
Carbon Dioxide
Carbon Monoxide
Isoflurane
