Document Detail

Factors affecting the concentration of compound A resulting from the degradation of sevoflurane by soda lime and Baralyme in a standard anesthetic circuit.
MedLine Citation:
PMID:  7653824     Owner:  NLM     Status:  MEDLINE    
Carbon dioxide absorbents, such as soda lime and Baralyme brand absorbent, convert sevoflurane to CF2 = C(CF3)OCH2F, a vinyl ether called "Compound A," whose toxicity raises concerns regarding the safety of sevoflurane in rebreathing circuits. Because an increased inflow rate to an anesthetic circuit decreases rebreathing, we assumed that an increased rate would proportionately decrease the concentration of Compound A. In the present report, we measured the Compound A concentration resulting from the action of wet (standard) soda lime and wet (standard) Baralyme on 2% sevoflurane in a model anesthetic circuit, using inflow rates (0.5, 1.0, 2.0, 4.0, and 6.0 L/min), ventilations (5 and 10 L/min), and carbon dioxide production/removal (200 and 400 mL/min) found in clinical practice. An increase in inflow rate decreased Compound A concentration to lower levels as inflow rate approached minute ventilation. At lower inflow rates, increasing duration of sevoflurane inflow increased the concentration of Compound A, a finding consistent with a progressive increase in absorbent temperature from absorption of carbon dioxide and consequently greater sevoflurane degradation. There was no material difference between Baralyme and soda lime in the concentrations of Compound A produced at a particular inflow rate. An increase in ventilation increased the concentration of Compound A, having a much greater effect at high rather than low inflow rates. An increase in amount of carbon dioxide absorbed also increased the concentration of Compound A. We conclude that inflow rate, ventilation, and carbon dioxide production are major determinants of the concentration of Compound A.
Z X Fang; E I Eger
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Anesthesia and analgesia     Volume:  81     ISSN:  0003-2999     ISO Abbreviation:  Anesth. Analg.     Publication Date:  1995 Sep 
Date Detail:
Created Date:  1995-09-26     Completed Date:  1995-09-26     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  1310650     Medline TA:  Anesth Analg     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  564-8     Citation Subset:  AIM; IM    
Department of Anesthesia, University of California, San Francisco 94143-0464, USA.
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MeSH Terms
Anesthesia / methods*
Barium Compounds / pharmacology*
Calcium Compounds*
Calcium Hydroxide / pharmacology*
Carbon Dioxide / chemistry
Ethers / chemistry*,  metabolism*
Hydrocarbons, Fluorinated / chemistry*
Methyl Ethers*
Potassium Compounds / pharmacology*
Respiration, Artificial
Sodium Hydroxide / pharmacology*
Vinyl Compounds / chemistry
Reg. No./Substance:
0/Barium Compounds; 0/Calcium Compounds; 0/Ethers; 0/Hydrocarbons, Fluorinated; 0/Methyl Ethers; 0/Oxides; 0/Potassium Compounds; 0/Vinyl Compounds; 109-93-3/vinyl ether; 124-38-9/Carbon Dioxide; 1305-62-0/Calcium Hydroxide; 1310-73-2/Sodium Hydroxide; 28523-86-6/sevoflurane; 39288-81-8/Baralyme; 58109-34-5/fluoromethyl 2,2-difluoro-1-(trifluoromethyl)vinyl ether; 8006-28-8/soda lime

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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