Lack of degradation of sevoflurane by a new carbon dioxide absorbent in humans.
BACKGROUND
Potent inhaled anesthetics degrade in the presence of the strong bases (sodium hydroxide or potassium hydroxide) in carbon dioxide (CO2) absorbents. A new absorbent, Amsorb (Armstrong Medical Ltd., Coleraine, Northern Ireland), does not employ these strong bases. This study compared the scavenging efficacy and compound A production of two commercially available absorbents (soda lime and barium hydroxide lime) with Amsorb in humans undergoing general anesthesia.


METHODS
Four healthy volunteers were anesthetized on different days with desflurane, sevoflurane, enflurane, and isoflurane. End-tidal carbon dioxide (ETCO2) and anesthetic concentrations were measured with infrared spectroscopy; blood pressure and arterial blood gases were obtained from a radial artery catheter. Each anesthetic exposure lasted 3 h, during which the three fresh (normally hydrated) CO2 absorbents were used for a period of 1 h each. Anesthesia was administered with a fresh gas flow rate of 2 l/min of air:oxygen (50:50). Tidal volume was 10 ml/kg; respiratory rate was 8 breaths/min. Arterial blood gases were obtained at baseline and after each hour. Inspired concentrations of compound A were measured after 15, 30, and 60 min of anesthetic administration for each CO2 absorbent.


RESULTS
Arterial blood gases and ETCO2 were not different among three CO2 absorbents. During sevoflurane, compound A formed with barium hydroxide lime and soda lime, but not with Amsorb.


CONCLUSIONS
This new CO2 absorbent effectively scavenged CO2 and was not associated with compound A production.
Mchaourab
A
A
Department of Anesthesiology, Medical College of Wisconsin and VA Medical Center, Milwaukee, USA.
Arain
S R
SR
Ebert
T J
TJ
D000042:Absorption; D000328:Adult; D000769:Anesthesia, Inhalation; D018685:Anesthetics, Inhalation / Q000737:chemistry*; D017609:Barium Compounds; D001784:Blood Gas Analysis; D002122:Calcium Chloride / Q000737:chemistry*; D017610:Calcium Compounds; D002126:Calcium Hydroxide / Q000737:chemistry*; D004987:Ethers / Q000737:chemistry; D005260:Female; D006801:Humans; D006845:Hydrocarbons, Fluorinated / Q000737:chemistry; D008297:Male; D008738:Methyl Ethers / Q000737:chemistry*; D010087:Oxides; D000077149:Sevoflurane; D012972:Sodium Hydroxide
C400293:Amsorb; D018685:Anesthetics, Inhalation; D017609:Barium Compounds; D017610:Calcium Compounds; D004987:Ethers; D006845:Hydrocarbons, Fluorinated; D008738:Methyl Ethers; D010087:Oxides; C012766:barium hydroxide; D000077149:Sevoflurane; C004569:soda lime; D012972:Sodium Hydroxide; C078742:fluoromethyl 2,2-difluoro-1-(trifluoromethyl)vinyl ether; D002122:Calcium Chloride; D002126:Calcium Hydroxide