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Pompiliu Ionescu - One of the best experts on this subject based on the ideXlab platform.
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the effect of anesthetic duration on kinetic and recovery characteristics of desflurane versus sevoflurane and on the kinetic characteristics of compound a in volunteers
Anesthesia & Analgesia, 1998Co-Authors: Edmond I Eger, Pompiliu Ionescu, Michael J Laster, Diane Gong, Donald D Koblin, Terri Bowland, Richard B WeiskopfAbstract:This study documents the differences in kinetics of 2 h (n = 7) and 4 h (n = 9) of 1.25 minimum alveolar anesthetic concentration (MAC) of desflurane (9.0%) versus (on a separate occasion) sevoflurane (3.0%), both administered in a fresh gas inflow of 2 L/min. These data are extensions of our previous 8-h (n = 7) studies of these anesthetics. By 10 min of anesthetic administration, average inspired (F (I)) and end-tidal concentration (FA) (FI/FA; the inverse of the more commonly used FA/FI) decreased to less than 1.15 for both anesthetics, with the difference from 1.0 nearly twice as great for sevoflurane as for desflurane. During all sevoflurane administrations, FA/FI for Compound A [CH2 F-O-C(=CF2) (CF3); a vinyl ether resulting from the degradation of sevoflurane by Baralyme[registered sign]] equaled approximately 0.8, and the average inspired concentration equaled approximately 40 ppm. Compound A is of interest because at approximately 150 ppm-h, it can induce biochemical and histological evidence of glomerular and tubular injury in rats and humans. During elimination, FA/FA0 for Compound A (FA0 is the last end-tidal concentration during anesthetic administration) decreased abruptly to 0 after 2 h and 4 h of anesthesia and to approximately 0.1 (FA approximately 3 ppm) after 8 h of anesthesia. In contrast, FA/FA0 for desflurane and sevoflurane decreased in a conventional, multiexponential manner, the decrease being increasingly delayed with increasing duration of anesthetic administration. FA/FA0 for sevoflurane exceeded that for desflurane for any given duration of anesthesia, and objective and subjective measures indicated a faster recovery with desflurane. Times (mean +/- SD) to initial response to command (2 h 10.9 +/- 1.2 vs 17.8 +/- 5.1 min, 4 h 11.3 +/- 2.1 vs 20.8 +/- 4.8 min, 8 h 14 +/- 4 vs 28 +/- 8 min) and orientation (2 h 12.7 +/- 1.6 vs 21.2 +/- 4.6 min, 4 h 14.8 +/- 3.1 vs 25.3 +/- 6.5 min, 8 h 19 +/- 4 vs 33 +/- 9 min) were shorter with desflurane. Recovery as defined by the digit symbol substitution test, P-deletion test, and Trieger test results was more rapid with desflurane. The incidence of vomiting was greater with sevoflurane after 8 h of anesthesia but not after shorter durations. We conclude that for each anesthetic duration, FI more closely approximates FA with desflurane during anesthetic administration, FA/FA0 decreases more rapidly after anesthesia with desflurane, and objective measures indicate more rapid recovery with desflurane. Finally, it seems that after 2-h and 4-h administrations, all Compound A taken up is bound within the body. Implications: Regardless of the duration of anesthesia, elimination is faster and recovery is quicker for the inhaled anesthetic desflurane than for the inhaled anesthetic sevoflurane. The toxic degradation product of sevoflurane, Compound A, seems to bind irreversibly to proteins in the body. (Anesth Analg 1998;86:414-21)
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Baralyme dehydration increases and soda lime dehydration decreases the concentration of compound a resulting from sevoflurane degradation in a standard anesthetic circuit
Anesthesia & Analgesia, 1997Co-Authors: Edmond I Eger, Pompiliu Ionescu, Michael J Laster, Richard B WeiskopfAbstract:Soda lime and Baralyme® brand carbon dioxide absorbents degrade sevoflurane to CF 2 =C(CF 3 )OCH 2 F, a potentially nephrotoxic vinyl ether called Compound A. Dehydration of these absorbents increases both the degradation of sevoflurane to Compound A and the degradation of Compound A. The balance between sevoflurane degradation and Compound A degradation determines the concentration of Compound A issuing from the absorbent (the net production of Compound A). We studied the effect of dehydration on the net production of Compound A in a simulated anesthetic circuit. Mimicking continuing oxygen delivery for 1, 2, or 3 days after completion of an anesthetic, we directed a conditioning fresh gas flow of 5 L/min or 10 L / min retrograde through fresh absorbent in situ in a standard absorbent system for 16, 40, and/or 64 h. The conditioned absorbent was subsequently used (without mixing of the granules) in a standard anesthetic circuit in which a 3-L rebreathing bag substituted for the lung. Metabolism was mimicked by introducing 250 mL/min carbon dioxide into the lung, and the lung was ventilated with a minute ventilation of 10 L/ min. At the same time, we introduced sevoflurane in a fresh gas inflow of 2 L / min at a concentration sufficient to produce an inspired concentration of 3.2%. Because of increased sevoflurane destruction by the absorbent, progressively longer periods of conditioning (dehydration) and / or higher inflow rates increased the delivered (vaporizer) concentration of sevoflurane required to sustain a 3.2% concentration. Dehydration of Baralyme® increased the inspired concentration of Compound A by up to sevenfold, whereas dehydration of soda lime markedly decreased the inspired concentration of Compound A. Implications: Economical delivery of modern inhaled anesthetics requires rebreathing of exhaled gases after removal of carbon dioxide. However, carbon dioxide absorbents (Baralyme®/soda lime) may degrade anesthetics to toxic substances. Baralyme® dehydration increases, and soda lime dehydration decreases, degradation of the inhaled anesthetic sevoflurane to the toxic substance, Compound A.
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factors affecting production of compound a from the interaction of sevoflurane with Baralyme and soda lime
Anesthesia & Analgesia, 1996Co-Authors: Zexu Fang, M J Laster, L Kandel, Pompiliu Ionescu, E. I EgerAbstract:Various alkali (e.g., soda lime) convert sevoflurane to CF2=C(CF3)OCH2F, a vinyl ether called "Compound A, " whose toxicity raises concerns regarding the safe administration of sevoflurane via rebreathing circuits. In the present investigation, we measured the sevoflurane degradation and output of Compound A caused by standard (13% water) Baralyme brand absorbent and standard (15% water) soda lime, and Baralyme and soda lime having various water contents (including no water). We used a flow-through system, applying a gas flow rate relative to absorbent volume that roughly equaled the rate/volume found in clinical practice. Both absorbents, at similar water contents, temperatures, and sevoflurane concentrations, produced roughly equal concentrations of Compound A. Dry and nearly dry absorbents produced less Compound A early in exposure to sevoflurane, and more later, than standard absorbents. Increases in temperature and sevoflurane concentration increased output of Compound A. Both absorbents, especially when dry, also destroyed Compound A, the concentration exiting from absorbent resulting from a complex sum of production and destruction. We conclude that the variability of concentrations of Compound A found in clinical practice may be largely explained by the inflow rate used (i.e., by rebreathing), sevoflurane concentration, and absorbent temperature and dryness. The effect of dryness is complex, with fresh dry absorbent destroying Compound A as it is made, and with dry absorbent that has been exposed to sevoflurane for a period of time providing a sometimes unusually high output of Compound A.
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carbon monoxide production from degradation of desflurane enflurane isoflurane halothane and sevoflurane by soda lime and Baralyme
Anesthesia & Analgesia, 1995Co-Authors: Zexu Fang, Edmond I Eger, M J Laster, Ben S Chortkoff, L Kandel, Pompiliu IonescuAbstract:Anecdotal reports suggest that soda lime and Baralyme brand absorbent can degrade inhaled anesthetics to carbon monoxide (CO). We examined the factors that govern CO production and found that these include: 1) The anesthetic used: for a given minimum alveolar anesthetic concentration (MAC)-multiple, the magnitude of CO production (greatest to least) is desflurane > or = enflurane > isoflurane >> halothane = sevoflurane. 2) The absorbent dryness: completely dry soda lime produces much more CO than absorbent with just 1.4% water content, and soda lime containing 4.8% or more water (standard soda lime contains 15% water) generates no CO. In contrast, both completely dry Baralyme and Baralyme with 1.6% water produce high concentrations of CO, and Baralyme containing 4.7% water produces concentrations equaling those produced by soda lime containing 1.4% water. Baralyme containing 9.7% or more water and standard Baralyme (13% water) do not generate CO.3) The type of absorbent: at a given water content, Baralyme produces more CO than does soda lime. 4) The temperature: an increased temperature increases CO production. 5) The anesthetic concentration: more CO is produced from higher anesthetic concentrations. These results suggest that CO generation can be avoided for all anesthetics by using soda lime with 4.8% (or more) water or Baralyme with 9.7% (or more) water, and by using inflow rates of less than 2-3 L/min. Such inflow rates are low enough to ensure that the absorbent does not dry out.
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carbon monoxide production from degradation of desflurane enflurane isoflurane halothane and sevoflurane by soda lime and Baralyme
Anesthesia & Analgesia, 1995Co-Authors: Zexu Fang, Edmond I Eger, M J Laster, Ben S Chortkoff, L Kandel, Pompiliu IonescuAbstract:Anecdotal reports suggest that soda lime and Baralyme Registered Trademark brand absorbent can degrade inhaled anesthetics to carbon monoxide (CO).We examined the factors that govern CO production and found that these include: 1) The anesthetic used: for a given minimum alveolar anesthetic concentration (MAC)-multiple, the magnitude of CO production (greatest to least) is desflurane >or=to enflurane > isoflurane much greater than halothane = sevoflurane. 2) The absorbent dryness: completely dry soda lime produces much more CO than absorbent with just 1.4% water content, and soda lime containing 4.8% or more water (standard soda lime contains 15% water) generates no CO. In contrast, both completely dry Baralyme Registered Trademark and Baralyme Registered Trademark with 1.6% water produce high concentrations of CO, and Baralyme Registered Trademark containing 4.7% water produces concentrations equaling those produced by soda lime containing 1.4% water. Baralyme Registered Trademark containing 9.7% or more water and standard Baralyme Registered Trademark (13% water) do not generate CO. 3) The type of absorbent: at a given water content, Baralyme Registered Trademark produces more CO than does soda lime. 4) The temperature: an increased temperature increases CO production. 5) The anesthetic concentration: more CO is produced from higher anesthetic concentrations. These results suggest that CO generation can be avoided for all anesthetics by using soda lime with 4.8% (or more) water or Baralyme Registered Trademark with 9.7% (or more) water, and by using inflow rates of less than 2-3 L/min. Such inflow rates are low enough to ensure that the absorbent does not dry out. (Anesth Analg 1995;80:1187-93)
Zexu Fang - One of the best experts on this subject based on the ideXlab platform.
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factors affecting production of compound a from the interaction of sevoflurane with Baralyme and soda lime
Anesthesia & Analgesia, 1996Co-Authors: Zexu Fang, M J Laster, L Kandel, Pompiliu Ionescu, E. I EgerAbstract:Various alkali (e.g., soda lime) convert sevoflurane to CF2=C(CF3)OCH2F, a vinyl ether called "Compound A, " whose toxicity raises concerns regarding the safe administration of sevoflurane via rebreathing circuits. In the present investigation, we measured the sevoflurane degradation and output of Compound A caused by standard (13% water) Baralyme brand absorbent and standard (15% water) soda lime, and Baralyme and soda lime having various water contents (including no water). We used a flow-through system, applying a gas flow rate relative to absorbent volume that roughly equaled the rate/volume found in clinical practice. Both absorbents, at similar water contents, temperatures, and sevoflurane concentrations, produced roughly equal concentrations of Compound A. Dry and nearly dry absorbents produced less Compound A early in exposure to sevoflurane, and more later, than standard absorbents. Increases in temperature and sevoflurane concentration increased output of Compound A. Both absorbents, especially when dry, also destroyed Compound A, the concentration exiting from absorbent resulting from a complex sum of production and destruction. We conclude that the variability of concentrations of Compound A found in clinical practice may be largely explained by the inflow rate used (i.e., by rebreathing), sevoflurane concentration, and absorbent temperature and dryness. The effect of dryness is complex, with fresh dry absorbent destroying Compound A as it is made, and with dry absorbent that has been exposed to sevoflurane for a period of time providing a sometimes unusually high output of Compound A.
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carbon monoxide production from degradation of desflurane enflurane isoflurane halothane and sevoflurane by soda lime and Baralyme
Anesthesia & Analgesia, 1995Co-Authors: Zexu Fang, Edmond I Eger, M J Laster, Ben S Chortkoff, L Kandel, Pompiliu IonescuAbstract:Anecdotal reports suggest that soda lime and Baralyme Registered Trademark brand absorbent can degrade inhaled anesthetics to carbon monoxide (CO).We examined the factors that govern CO production and found that these include: 1) The anesthetic used: for a given minimum alveolar anesthetic concentration (MAC)-multiple, the magnitude of CO production (greatest to least) is desflurane >or=to enflurane > isoflurane much greater than halothane = sevoflurane. 2) The absorbent dryness: completely dry soda lime produces much more CO than absorbent with just 1.4% water content, and soda lime containing 4.8% or more water (standard soda lime contains 15% water) generates no CO. In contrast, both completely dry Baralyme Registered Trademark and Baralyme Registered Trademark with 1.6% water produce high concentrations of CO, and Baralyme Registered Trademark containing 4.7% water produces concentrations equaling those produced by soda lime containing 1.4% water. Baralyme Registered Trademark containing 9.7% or more water and standard Baralyme Registered Trademark (13% water) do not generate CO. 3) The type of absorbent: at a given water content, Baralyme Registered Trademark produces more CO than does soda lime. 4) The temperature: an increased temperature increases CO production. 5) The anesthetic concentration: more CO is produced from higher anesthetic concentrations. These results suggest that CO generation can be avoided for all anesthetics by using soda lime with 4.8% (or more) water or Baralyme Registered Trademark with 9.7% (or more) water, and by using inflow rates of less than 2-3 L/min. Such inflow rates are low enough to ensure that the absorbent does not dry out. (Anesth Analg 1995;80:1187-93)
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carbon monoxide production from degradation of desflurane enflurane isoflurane halothane and sevoflurane by soda lime and Baralyme
Anesthesia & Analgesia, 1995Co-Authors: Zexu Fang, Edmond I Eger, M J Laster, Ben S Chortkoff, L Kandel, Pompiliu IonescuAbstract:Anecdotal reports suggest that soda lime and Baralyme brand absorbent can degrade inhaled anesthetics to carbon monoxide (CO). We examined the factors that govern CO production and found that these include: 1) The anesthetic used: for a given minimum alveolar anesthetic concentration (MAC)-multiple, the magnitude of CO production (greatest to least) is desflurane > or = enflurane > isoflurane >> halothane = sevoflurane. 2) The absorbent dryness: completely dry soda lime produces much more CO than absorbent with just 1.4% water content, and soda lime containing 4.8% or more water (standard soda lime contains 15% water) generates no CO. In contrast, both completely dry Baralyme and Baralyme with 1.6% water produce high concentrations of CO, and Baralyme containing 4.7% water produces concentrations equaling those produced by soda lime containing 1.4% water. Baralyme containing 9.7% or more water and standard Baralyme (13% water) do not generate CO.3) The type of absorbent: at a given water content, Baralyme produces more CO than does soda lime. 4) The temperature: an increased temperature increases CO production. 5) The anesthetic concentration: more CO is produced from higher anesthetic concentrations. These results suggest that CO generation can be avoided for all anesthetics by using soda lime with 4.8% (or more) water or Baralyme with 9.7% (or more) water, and by using inflow rates of less than 2-3 L/min. Such inflow rates are low enough to ensure that the absorbent does not dry out.
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Factors affecting the concentration of compound A resulting from the degradation of sevoflurane by soda lime and Baralyme in a standard anesthetic circuit.
Anesthesia & Analgesia, 1995Co-Authors: Zexu Fang, E. I EgerAbstract:Carbon dioxide absorbents, such as soda lime and Baralyme Registered Trademark brand absorbent, convert sevoflurane to CF2 = C(CF3)OCH2 F, 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 Registered Trademark 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 Registered Trademark 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. (Anesth Analg 1995;81:564-8)
Kazuyuki Ikeda - One of the best experts on this subject based on the ideXlab platform.
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effects of low flow sevoflurane anesthesia on renal function comparison with high flow sevoflurane anesthesia and low flow isoflurane anesthesia
Anesthesiology, 1997Co-Authors: Hiromichi Bito, Yukako Ikeuchi, Kazuyuki IkedaAbstract:Background: The safety of low-flow sevoflurane anesthesia, during which CF2 = C(CF3)-O-CH2 F (compound A) is formed by sevoflurane degradation, in humans has been questioned because compound A is nephrotoxic in rats. Several reports have evaluated renal function after closed-circuit or low-flow sevoflurane anesthesia, using blood urea nitrogen (BUN) and serum creatinine as markers. However, these are not the more sensitive tests for detecting renal damage. This study assessed the effects of low-flow sevoflurane anesthesia on renal function using not only BUN and serum creatinine but also creatinine clearance and urinary excretion of kidney-specific enzymes, and it compared these values with those obtained in high-flow sevoflurane anesthesia and low-flow isoflurane anesthesia. Methods: Forty-eight patients with gastric cancer undergoing gastrectomy were studied. Patients were randomized to receive sevoflurane anesthesia with fresh gas flow of 1 l/min (low-flow sevoflurane group; n = 16) or 6–10 l/min (high-flow sevoflurane group; n = 16) or isoflurane anesthesia with a fresh gas flow of 1 l/min (low-flow isoflurane group; n = 16). In all groups, the carrier gas was oxygen/nitrous oxide in the ratio adjusted to ensure a fractional concentration of oxygen in inspired gas (FiO2) of more than 0.3. Fresh Baralyme was used in the low-flow sevoflurane and low-flow isoflurane groups. Glass balls were used instead in the high-flow sevoflurane group, with the fresh gas flow rate adjusted to eliminate rebreathing. The compound A concentration was measured by gas chromatography. Gas samples taken from the inspiratory limb of the circle system at 1-h intervals were analyzed. Blood samples were obtained before and on days 1, 2, and 3 after anesthesia to measure BUN and serum creatinine. Twenty-four-hour urine samples were collected before anesthesia and for each 24-h period from 0 to 72 h after anesthesia to measure creatinine, N-acetyl-beta-D-glucosaminidase, and alanine aminopeptidase. Results: The average inspired concentration of compound A was 20 +/- 7.8 ppm (mean +/- SD), and the average duration of exposure to this concentration was 6.11 +/- 1.77 h in the low-flow sevoflurane group. Postanesthesia BUN and serum creatinine concentrations decreased, creatinine clearance increased, and urinary N-acetyl-beta-D-glucosaminidase and alanine aminopeptidase excretion increased in all groups compared with preanesthesia values, but there were no significant differences between the low-flow sevoflurane, high-flow sevoflurane, and low-flow isoflurane groups for any renal function parameter at any time after anesthesia. Conclusions: The only difference between the low-flow and high-flow sevoflurane groups was compound A formation, and postanesthesia laboratory data showed no significant effects of compound A formation during sevoflurane anesthesia on renal function. No significant effects on renal function were observed in either the low-flow or high-flow sevoflurane groups compared with the low-flow isoflurane group.
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long duration low flow sevoflurane anesthesia using two carbon dioxide absorbents quantification of degradation products in the circuit
Anesthesiology, 1994Co-Authors: Hiromichi Bito, Kazuyuki IkedaAbstract:BACKGROUND: Sevoflurane reacts with soda lime, generating degradation products. The concentrations of sevoflurane degradation products in a low-flow circuit have been reported for anesthesia times of less than 5 h. In this study, sevoflurane degradation products generated during low-flow anesthesia exceeding 10 h were examined. METHODS: Sixteen patients received sevoflurane anesthesia with a fresh gas flow rate of 11/min. In eight patients, soda lime was used as the CO2 absorbent; in the other eight patients, Baralyme was used. During anesthesia, the concentrations of degradation products in the circuit, the temperature of the CO2 absorbent, inspired and end-tidal sevoflurane concentrations, and the volume of CO2 eliminated by the patient were measured. Gas was sampled from the inspiratory limb of the circuit and analyzed by gas chromatography. RESULTS: Two degradation products, CF2 = C(CF3)-O-CH2F (compound A) and CH3OCF2CH(CF3)OCH2F (compound B), were detected. In the soda lime group, the individual maximum concentration of compound A was 23.6 +/- 2.9 (12.0-37.4) ppm. In the Baralyme group, the concentration was 32.0 +/- 2.3 (23.5-41.3) ppm. The individual maximum concentration of compound A in the Baralyme group was significant higher than A in the Baralyme group was significant higher than that in the soda lime group. Compound B was detected in two patients, reaching a maximum concentration of 0.2 ppm. The end-tidal sevoflurane concentration, temperature of the CO2 absorbent, and volume of CO2 eliminated by the patient were the same in both groups. CONCLUSIONS: The degradation products detected were at low concentrations in long-duration, low-flow anesthesia with sevoflurane. Baralyme produced higher concentrations of degradation products than soda lime.
Edmond I Eger - One of the best experts on this subject based on the ideXlab platform.
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the effect of anesthetic duration on kinetic and recovery characteristics of desflurane versus sevoflurane and on the kinetic characteristics of compound a in volunteers
Anesthesia & Analgesia, 1998Co-Authors: Edmond I Eger, Pompiliu Ionescu, Michael J Laster, Diane Gong, Donald D Koblin, Terri Bowland, Richard B WeiskopfAbstract:This study documents the differences in kinetics of 2 h (n = 7) and 4 h (n = 9) of 1.25 minimum alveolar anesthetic concentration (MAC) of desflurane (9.0%) versus (on a separate occasion) sevoflurane (3.0%), both administered in a fresh gas inflow of 2 L/min. These data are extensions of our previous 8-h (n = 7) studies of these anesthetics. By 10 min of anesthetic administration, average inspired (F (I)) and end-tidal concentration (FA) (FI/FA; the inverse of the more commonly used FA/FI) decreased to less than 1.15 for both anesthetics, with the difference from 1.0 nearly twice as great for sevoflurane as for desflurane. During all sevoflurane administrations, FA/FI for Compound A [CH2 F-O-C(=CF2) (CF3); a vinyl ether resulting from the degradation of sevoflurane by Baralyme[registered sign]] equaled approximately 0.8, and the average inspired concentration equaled approximately 40 ppm. Compound A is of interest because at approximately 150 ppm-h, it can induce biochemical and histological evidence of glomerular and tubular injury in rats and humans. During elimination, FA/FA0 for Compound A (FA0 is the last end-tidal concentration during anesthetic administration) decreased abruptly to 0 after 2 h and 4 h of anesthesia and to approximately 0.1 (FA approximately 3 ppm) after 8 h of anesthesia. In contrast, FA/FA0 for desflurane and sevoflurane decreased in a conventional, multiexponential manner, the decrease being increasingly delayed with increasing duration of anesthetic administration. FA/FA0 for sevoflurane exceeded that for desflurane for any given duration of anesthesia, and objective and subjective measures indicated a faster recovery with desflurane. Times (mean +/- SD) to initial response to command (2 h 10.9 +/- 1.2 vs 17.8 +/- 5.1 min, 4 h 11.3 +/- 2.1 vs 20.8 +/- 4.8 min, 8 h 14 +/- 4 vs 28 +/- 8 min) and orientation (2 h 12.7 +/- 1.6 vs 21.2 +/- 4.6 min, 4 h 14.8 +/- 3.1 vs 25.3 +/- 6.5 min, 8 h 19 +/- 4 vs 33 +/- 9 min) were shorter with desflurane. Recovery as defined by the digit symbol substitution test, P-deletion test, and Trieger test results was more rapid with desflurane. The incidence of vomiting was greater with sevoflurane after 8 h of anesthesia but not after shorter durations. We conclude that for each anesthetic duration, FI more closely approximates FA with desflurane during anesthetic administration, FA/FA0 decreases more rapidly after anesthesia with desflurane, and objective measures indicate more rapid recovery with desflurane. Finally, it seems that after 2-h and 4-h administrations, all Compound A taken up is bound within the body. Implications: Regardless of the duration of anesthesia, elimination is faster and recovery is quicker for the inhaled anesthetic desflurane than for the inhaled anesthetic sevoflurane. The toxic degradation product of sevoflurane, Compound A, seems to bind irreversibly to proteins in the body. (Anesth Analg 1998;86:414-21)
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dehydration of Baralyme increases compound a resulting from sevoflurane degradation in a standard anesthetic circuit used to anesthetize swine
Anesthesia & Analgesia, 1997Co-Authors: Eugene Steffey, Edmond I Eger, Michael J Laster, Pompilliu Ionescu, Diane Gong, Richard B WeiskopfAbstract:In a model anesthetic circuit, dehydration of Baralyme[registered sign] brand carbon dioxide absorbent increases degradation of sevoflurane to CF2=C(CF3)OCH2 F, a nephrotoxic vinyl ether called Compound A.In the present study, we quantified this increase using "conditioned" Baralyme[registered sign] in a circle absorbent system to deliver sevoflurane anesthesia to swine. Mimicking continuing oxygen delivery for 2 days after completion of an anesthetic, we directed a conditioning fresh gas flow of 5 L/min retrograde through fresh absorbent in situ in a standard absorbent system for 40 h. The conditioned absorbent was subsequently used (without mixing of the granules) in a standard anesthetic circuit to deliver sevoflurane to swine weighing 78 +/- 2 kg. The initial inflow rate of fresh gas flow was set at 10 L/min with the vaporizer at 8% to achieve the target end-tidal concentration of 3.0%-3.2% sevoflurane in approximately 20 min. The flow was later decreased to 2 L/min, and the vaporizer concentration was decreased to sustain the 3.0%-3.2% value for a total of 2 h (three pigs) or 4 h (eight pigs). Inspired Compound A increased over the first 30-60 min to a peak concentration of 357 +/- 49 ppm (mean +/- SD), slowly decreasing thereafter to 74 +/- 6 ppm at 4 h. The average concentration over 2 h was 208 +/- 25 ppm, and the average concentration over 4 h was 153 +/- 19 ppm. Pigs were killed 1 or 4 days after anesthesia. The kidneys from pigs anesthetized for both 2 h and 4 h showed mild inflammation but little or no tubular necrosis. These results suggest that dehydration of Baralyme[registered sign] may produce concentrations of Compound A that would have nephrotoxic effects in humans in a shorter time than would be the case with normally hydrated Baralyme[registered sign]. Implications: The vapor known as Compound A can injure the kidney. Dehydration of Baralyme[registered sign], a standard absorbent of carbon dioxide in inhaled anesthetic delivery systems, can cause a 5- to 10-fold increase in Compound A concentrations produced from the inhaled anesthetic, sevoflurane, given at anesthetizing concentrations in a conventional anesthetic system. (Anesth Analg 1997;85:1382-6)
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Baralyme dehydration increases and soda lime dehydration decreases the concentration of compound a resulting from sevoflurane degradation in a standard anesthetic circuit
Anesthesia & Analgesia, 1997Co-Authors: Edmond I Eger, Pompiliu Ionescu, Michael J Laster, Richard B WeiskopfAbstract:Soda lime and Baralyme® brand carbon dioxide absorbents degrade sevoflurane to CF 2 =C(CF 3 )OCH 2 F, a potentially nephrotoxic vinyl ether called Compound A. Dehydration of these absorbents increases both the degradation of sevoflurane to Compound A and the degradation of Compound A. The balance between sevoflurane degradation and Compound A degradation determines the concentration of Compound A issuing from the absorbent (the net production of Compound A). We studied the effect of dehydration on the net production of Compound A in a simulated anesthetic circuit. Mimicking continuing oxygen delivery for 1, 2, or 3 days after completion of an anesthetic, we directed a conditioning fresh gas flow of 5 L/min or 10 L / min retrograde through fresh absorbent in situ in a standard absorbent system for 16, 40, and/or 64 h. The conditioned absorbent was subsequently used (without mixing of the granules) in a standard anesthetic circuit in which a 3-L rebreathing bag substituted for the lung. Metabolism was mimicked by introducing 250 mL/min carbon dioxide into the lung, and the lung was ventilated with a minute ventilation of 10 L/ min. At the same time, we introduced sevoflurane in a fresh gas inflow of 2 L / min at a concentration sufficient to produce an inspired concentration of 3.2%. Because of increased sevoflurane destruction by the absorbent, progressively longer periods of conditioning (dehydration) and / or higher inflow rates increased the delivered (vaporizer) concentration of sevoflurane required to sustain a 3.2% concentration. Dehydration of Baralyme® increased the inspired concentration of Compound A by up to sevenfold, whereas dehydration of soda lime markedly decreased the inspired concentration of Compound A. Implications: Economical delivery of modern inhaled anesthetics requires rebreathing of exhaled gases after removal of carbon dioxide. However, carbon dioxide absorbents (Baralyme®/soda lime) may degrade anesthetics to toxic substances. Baralyme® dehydration increases, and soda lime dehydration decreases, degradation of the inhaled anesthetic sevoflurane to the toxic substance, Compound A.
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carbon monoxide production from degradation of desflurane enflurane isoflurane halothane and sevoflurane by soda lime and Baralyme
Anesthesia & Analgesia, 1995Co-Authors: Zexu Fang, Edmond I Eger, M J Laster, Ben S Chortkoff, L Kandel, Pompiliu IonescuAbstract:Anecdotal reports suggest that soda lime and Baralyme brand absorbent can degrade inhaled anesthetics to carbon monoxide (CO). We examined the factors that govern CO production and found that these include: 1) The anesthetic used: for a given minimum alveolar anesthetic concentration (MAC)-multiple, the magnitude of CO production (greatest to least) is desflurane > or = enflurane > isoflurane >> halothane = sevoflurane. 2) The absorbent dryness: completely dry soda lime produces much more CO than absorbent with just 1.4% water content, and soda lime containing 4.8% or more water (standard soda lime contains 15% water) generates no CO. In contrast, both completely dry Baralyme and Baralyme with 1.6% water produce high concentrations of CO, and Baralyme containing 4.7% water produces concentrations equaling those produced by soda lime containing 1.4% water. Baralyme containing 9.7% or more water and standard Baralyme (13% water) do not generate CO.3) The type of absorbent: at a given water content, Baralyme produces more CO than does soda lime. 4) The temperature: an increased temperature increases CO production. 5) The anesthetic concentration: more CO is produced from higher anesthetic concentrations. These results suggest that CO generation can be avoided for all anesthetics by using soda lime with 4.8% (or more) water or Baralyme with 9.7% (or more) water, and by using inflow rates of less than 2-3 L/min. Such inflow rates are low enough to ensure that the absorbent does not dry out.
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carbon monoxide production from degradation of desflurane enflurane isoflurane halothane and sevoflurane by soda lime and Baralyme
Anesthesia & Analgesia, 1995Co-Authors: Zexu Fang, Edmond I Eger, M J Laster, Ben S Chortkoff, L Kandel, Pompiliu IonescuAbstract:Anecdotal reports suggest that soda lime and Baralyme Registered Trademark brand absorbent can degrade inhaled anesthetics to carbon monoxide (CO).We examined the factors that govern CO production and found that these include: 1) The anesthetic used: for a given minimum alveolar anesthetic concentration (MAC)-multiple, the magnitude of CO production (greatest to least) is desflurane >or=to enflurane > isoflurane much greater than halothane = sevoflurane. 2) The absorbent dryness: completely dry soda lime produces much more CO than absorbent with just 1.4% water content, and soda lime containing 4.8% or more water (standard soda lime contains 15% water) generates no CO. In contrast, both completely dry Baralyme Registered Trademark and Baralyme Registered Trademark with 1.6% water produce high concentrations of CO, and Baralyme Registered Trademark containing 4.7% water produces concentrations equaling those produced by soda lime containing 1.4% water. Baralyme Registered Trademark containing 9.7% or more water and standard Baralyme Registered Trademark (13% water) do not generate CO. 3) The type of absorbent: at a given water content, Baralyme Registered Trademark produces more CO than does soda lime. 4) The temperature: an increased temperature increases CO production. 5) The anesthetic concentration: more CO is produced from higher anesthetic concentrations. These results suggest that CO generation can be avoided for all anesthetics by using soda lime with 4.8% (or more) water or Baralyme Registered Trademark with 9.7% (or more) water, and by using inflow rates of less than 2-3 L/min. Such inflow rates are low enough to ensure that the absorbent does not dry out. (Anesth Analg 1995;80:1187-93)
Richard B Weiskopf - One of the best experts on this subject based on the ideXlab platform.
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the effect of anesthetic duration on kinetic and recovery characteristics of desflurane versus sevoflurane and on the kinetic characteristics of compound a in volunteers
Anesthesia & Analgesia, 1998Co-Authors: Edmond I Eger, Pompiliu Ionescu, Michael J Laster, Diane Gong, Donald D Koblin, Terri Bowland, Richard B WeiskopfAbstract:This study documents the differences in kinetics of 2 h (n = 7) and 4 h (n = 9) of 1.25 minimum alveolar anesthetic concentration (MAC) of desflurane (9.0%) versus (on a separate occasion) sevoflurane (3.0%), both administered in a fresh gas inflow of 2 L/min. These data are extensions of our previous 8-h (n = 7) studies of these anesthetics. By 10 min of anesthetic administration, average inspired (F (I)) and end-tidal concentration (FA) (FI/FA; the inverse of the more commonly used FA/FI) decreased to less than 1.15 for both anesthetics, with the difference from 1.0 nearly twice as great for sevoflurane as for desflurane. During all sevoflurane administrations, FA/FI for Compound A [CH2 F-O-C(=CF2) (CF3); a vinyl ether resulting from the degradation of sevoflurane by Baralyme[registered sign]] equaled approximately 0.8, and the average inspired concentration equaled approximately 40 ppm. Compound A is of interest because at approximately 150 ppm-h, it can induce biochemical and histological evidence of glomerular and tubular injury in rats and humans. During elimination, FA/FA0 for Compound A (FA0 is the last end-tidal concentration during anesthetic administration) decreased abruptly to 0 after 2 h and 4 h of anesthesia and to approximately 0.1 (FA approximately 3 ppm) after 8 h of anesthesia. In contrast, FA/FA0 for desflurane and sevoflurane decreased in a conventional, multiexponential manner, the decrease being increasingly delayed with increasing duration of anesthetic administration. FA/FA0 for sevoflurane exceeded that for desflurane for any given duration of anesthesia, and objective and subjective measures indicated a faster recovery with desflurane. Times (mean +/- SD) to initial response to command (2 h 10.9 +/- 1.2 vs 17.8 +/- 5.1 min, 4 h 11.3 +/- 2.1 vs 20.8 +/- 4.8 min, 8 h 14 +/- 4 vs 28 +/- 8 min) and orientation (2 h 12.7 +/- 1.6 vs 21.2 +/- 4.6 min, 4 h 14.8 +/- 3.1 vs 25.3 +/- 6.5 min, 8 h 19 +/- 4 vs 33 +/- 9 min) were shorter with desflurane. Recovery as defined by the digit symbol substitution test, P-deletion test, and Trieger test results was more rapid with desflurane. The incidence of vomiting was greater with sevoflurane after 8 h of anesthesia but not after shorter durations. We conclude that for each anesthetic duration, FI more closely approximates FA with desflurane during anesthetic administration, FA/FA0 decreases more rapidly after anesthesia with desflurane, and objective measures indicate more rapid recovery with desflurane. Finally, it seems that after 2-h and 4-h administrations, all Compound A taken up is bound within the body. Implications: Regardless of the duration of anesthesia, elimination is faster and recovery is quicker for the inhaled anesthetic desflurane than for the inhaled anesthetic sevoflurane. The toxic degradation product of sevoflurane, Compound A, seems to bind irreversibly to proteins in the body. (Anesth Analg 1998;86:414-21)
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dehydration of Baralyme increases compound a resulting from sevoflurane degradation in a standard anesthetic circuit used to anesthetize swine
Anesthesia & Analgesia, 1997Co-Authors: Eugene Steffey, Edmond I Eger, Michael J Laster, Pompilliu Ionescu, Diane Gong, Richard B WeiskopfAbstract:In a model anesthetic circuit, dehydration of Baralyme[registered sign] brand carbon dioxide absorbent increases degradation of sevoflurane to CF2=C(CF3)OCH2 F, a nephrotoxic vinyl ether called Compound A.In the present study, we quantified this increase using "conditioned" Baralyme[registered sign] in a circle absorbent system to deliver sevoflurane anesthesia to swine. Mimicking continuing oxygen delivery for 2 days after completion of an anesthetic, we directed a conditioning fresh gas flow of 5 L/min retrograde through fresh absorbent in situ in a standard absorbent system for 40 h. The conditioned absorbent was subsequently used (without mixing of the granules) in a standard anesthetic circuit to deliver sevoflurane to swine weighing 78 +/- 2 kg. The initial inflow rate of fresh gas flow was set at 10 L/min with the vaporizer at 8% to achieve the target end-tidal concentration of 3.0%-3.2% sevoflurane in approximately 20 min. The flow was later decreased to 2 L/min, and the vaporizer concentration was decreased to sustain the 3.0%-3.2% value for a total of 2 h (three pigs) or 4 h (eight pigs). Inspired Compound A increased over the first 30-60 min to a peak concentration of 357 +/- 49 ppm (mean +/- SD), slowly decreasing thereafter to 74 +/- 6 ppm at 4 h. The average concentration over 2 h was 208 +/- 25 ppm, and the average concentration over 4 h was 153 +/- 19 ppm. Pigs were killed 1 or 4 days after anesthesia. The kidneys from pigs anesthetized for both 2 h and 4 h showed mild inflammation but little or no tubular necrosis. These results suggest that dehydration of Baralyme[registered sign] may produce concentrations of Compound A that would have nephrotoxic effects in humans in a shorter time than would be the case with normally hydrated Baralyme[registered sign]. Implications: The vapor known as Compound A can injure the kidney. Dehydration of Baralyme[registered sign], a standard absorbent of carbon dioxide in inhaled anesthetic delivery systems, can cause a 5- to 10-fold increase in Compound A concentrations produced from the inhaled anesthetic, sevoflurane, given at anesthetizing concentrations in a conventional anesthetic system. (Anesth Analg 1997;85:1382-6)
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Baralyme dehydration increases and soda lime dehydration decreases the concentration of compound a resulting from sevoflurane degradation in a standard anesthetic circuit
Anesthesia & Analgesia, 1997Co-Authors: Edmond I Eger, Pompiliu Ionescu, Michael J Laster, Richard B WeiskopfAbstract:Soda lime and Baralyme® brand carbon dioxide absorbents degrade sevoflurane to CF 2 =C(CF 3 )OCH 2 F, a potentially nephrotoxic vinyl ether called Compound A. Dehydration of these absorbents increases both the degradation of sevoflurane to Compound A and the degradation of Compound A. The balance between sevoflurane degradation and Compound A degradation determines the concentration of Compound A issuing from the absorbent (the net production of Compound A). We studied the effect of dehydration on the net production of Compound A in a simulated anesthetic circuit. Mimicking continuing oxygen delivery for 1, 2, or 3 days after completion of an anesthetic, we directed a conditioning fresh gas flow of 5 L/min or 10 L / min retrograde through fresh absorbent in situ in a standard absorbent system for 16, 40, and/or 64 h. The conditioned absorbent was subsequently used (without mixing of the granules) in a standard anesthetic circuit in which a 3-L rebreathing bag substituted for the lung. Metabolism was mimicked by introducing 250 mL/min carbon dioxide into the lung, and the lung was ventilated with a minute ventilation of 10 L/ min. At the same time, we introduced sevoflurane in a fresh gas inflow of 2 L / min at a concentration sufficient to produce an inspired concentration of 3.2%. Because of increased sevoflurane destruction by the absorbent, progressively longer periods of conditioning (dehydration) and / or higher inflow rates increased the delivered (vaporizer) concentration of sevoflurane required to sustain a 3.2% concentration. Dehydration of Baralyme® increased the inspired concentration of Compound A by up to sevenfold, whereas dehydration of soda lime markedly decreased the inspired concentration of Compound A. Implications: Economical delivery of modern inhaled anesthetics requires rebreathing of exhaled gases after removal of carbon dioxide. However, carbon dioxide absorbents (Baralyme®/soda lime) may degrade anesthetics to toxic substances. Baralyme® dehydration increases, and soda lime dehydration decreases, degradation of the inhaled anesthetic sevoflurane to the toxic substance, Compound A.
