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Eapen, Asha Sarah. Arun Kumar A. Insufficient data exist on the production of compound A during closed-system sevoflurane administration with newer carbon dioxide absorbents. Ventilation was set to obtain an end-tidal carbon dioxide partial pressure of approximately 40 mmHg. After baseline analysis, liquid sevoflurane was injected into the circuit by syringe pump to obtain 2. At baseline and at regular intervals thereafter, end-tidal carbon dioxide partial pressure, end-tidal sevoflurane concentration, and canister inflow T degrees in and canister outflow T degrees out temperatures were measured.
To measure compound Ainsp concentration in the inspired gas of the breathing circuit, 2-ml gas samples were taken and analyzed by capillary gas chromatography plus mass spectrometry.
The median minimum-maximum highest compound Ainsp concentrations over the entire period were, in decreasing order: After reaching their peak concentration, a decrease for Sofnolime, KOH-free Sodasorb, and Sodasorb until min was found.
Sodasorb , respectively. Whether compound A has an effect clinically on renal function has been debated, but some authors question the use of sevoflurane in low-flow conditions. However, they are highly reactive compounds, which cause the breakdown of sevoflurane in the canister in the breathing circuit. In experimental conditions the formation of compound A was reportedly less with KOH-free soda limes, 3 which were then produced by various companies, and alternate NaOH-free and KOH-free carbon dioxide absorbents became available.
The aim of this study was to measure the formation of compound A during in vitro closed-system sevoflurane administration, using five different carbon dioxide absorbents whereby results were obtained during a previous study performed in the department in almost identical circumstances 6 : 1 KOH-free soda limes Sofnolime and KOH-free Sodasorb; Molecular Products, Thaxted, UK, and Grace, Epernon, France, respectively ; 2 NaOH-free and KOH-free absorbents Amsorb 5 ; and lithium hydroxide; Armstrong, Coleraine, Northern Ireland and Chemetall, Frankfurt, Germany, respectively ; and 3 classic sodalime Sodasorb Grace.
A special artificial test lung was used. This gas was brought to a stand-alone Ultima gas analyzer Datex, Helsinki, Finland for measuring all respiratory gases. The outlet gases of the gas analyzer were scavenged. It has been shown that by this modification, in contrast to the original PhysioFlex machine, compound A is generated in larger quantities.
The experimental setup was cleaned before each use and checked carefully for complete air-tightness. After initial preparation and equilibration, liquid sevoflurane was injected with a syringe pump Model ; Graseby, Watford, United Kingdom into a small copper reservoir included in the breathing circuit.
The aim was an end-tidal sevoflurane concentration of 2. Two thermistors Arbo, Yellow Springs, OH were introduced into the absorbent lime canister, which has a capacity of ml CO 2 absorbent, to measure the temperature. Gas samples of 2 ml were taken by means of airtight syringes for the determination of compound A. The syringes were connected to the breathing circuit using three-way valves and Luer-lock connections, one in the inspiratory limb for compound A insp measurement and one in the expiratory limb for compound A exp measurement of the breathing circuit.
The gas samples were transferred immediately to glass headspace vials and stored briefly at room temperature. The mass spectrometric detector was operated in the full-scan mode.
Before each analysis a standard curve consisting of eight points, including a zero-calibrator, was prepared and injected. Standards of compound A in the gas phase were prepared starting from liquid volumetric dilutions of stock solutions of compound A and sevoflurane in ethyl acetate.
Before analysis, 0. Calibration curves were linear over a range of 0. An average correlation coefficient of 0. The coefficients of variation varied from 4.
The limit of detection, using the signal-to-noise criterion 3, was 0. A total of 33 independent runs were made. Classic soda lime Sodasorb was previously used in six runs; KOH-free soda lime Sofnolime and KOH-free Sodasorb were used in six and seven runs, respectively; alternate carbon dioxide absorbents Amsorb and lithium hydroxide were used in seven runs each.
Their chemical composition, according to the available information, is shown in table 1. During the preparation of the test-lung setup new carbon dioxide absorbent ml was always used. For the first Sodasorb runs, a minimal amount of 0. To summarize repeated measures over time for all variables, areas under the curve AUCs were calculated for individual runs. For overall comparisons of the AUCs between the five groups, the Kruskal-Wallis test was applied, followed by Wilcoxon rank sum tests for multiple pairwise comparisons.
To compare the difference between compound A insp and compound A exp , within-group Wilcoxon signed rank tests were applied on the AUCs of the individual runs. The same test was applied to compare within group adjacent time points. The median values for end-tidal carbon dioxide partial pressure 40—42 mmHg and for end-tidal sevoflurane concentration 2. The total median with range amounts in millimeters of liquid sevoflurane injected into the circuit during the min examination period were 7.
The results for compound A insp with the different carbon dioxide absorbents are shown in figure 1. Learn more. Why can potassium hydroxide not be used to remove atmospheric carbon dioxide? Ask Question. Asked 7 years, 8 months ago. Active 7 years, 8 months ago. Viewed 11k times.
Improve this question. Klaus-Dieter Warzecha MathGod MathGod 1 1 gold badge 3 3 silver badges 6 6 bronze badges. Add a comment. Active Oldest Votes. Improve this answer. Nevertheless, when properly embedded in filtering devices, they can safe lifes because they can prevent self-poisoning by carbon dioxide.
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