Degradation products of different water content sevoflurane in carbon dioxide absorbents by gas chromatography-mass spectrometry analysis / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Sevoflurane is currently used as a volatile inhalation anesthetic with many clinical advantages. A representative degradation product, compound A, was quantitatively measured to investigate whether there are different reactions between two kinds of water content sevoflurane formulations with different carbon dioxide (CO2) absorbents.</p><p><b>METHODS</b>A closed-circle breathe bag with the Dräger Fabius GS anesthesia apparatus was used as an artificial rubber lung. The experiments were grouped according to different sevoflurane formulations: group A: higher-water sevoflurane (Ultane); group B: lower-water sevoflurane (Sevoness). During the experiment, CO2 (200 ml/min) was continually perfused to keep the end-tidal pressure of CO2 (P(ET)CO2) at 35 - 45 mmHg. The artificial ventilation was set to 6 L/min, and the breathing rate at 12 breaths/min. The circuit was operated with constant fresh gas flow rate (1 L/min) and the sevoflurane concentration was kept at 1.0 minimum alveolar concentration (MAC) for 240 minutes. At 0, 10, 20, 30, 60, 90, 120, 180 and 240 minutes, gas was collected from the Y-piece. Gas chromatography/mass spectrometry (GC/MS) was used to quantify the major degradation product, compound A, with different water content sevoflurane. PETCO2 and sevoflurane concentration, and the temperature of the canister were continuously monitored during the experiment.</p><p><b>RESULTS</b>There were no significant differences in P(ET)CO2 and sevoflurane concentrations between the two groups. Drägersorb 800 plus produced the highest concentrations of compound A compared with other sodalimes, and Sevoness in Drägersorb 800 plus generated more compound A than Ultane (P < 0.05). There were significant differences in the peak and average compound A concentrations between Ultane and Sevoness with Drägersorb 800 plus (P < 0.05), while the compound A concentration produced by Sodasorb grase and sofonolime in the two groups showed no significant difference (P > 0.05). In the same group, the peak and average of compound A concentration produced by Sodasorb grase and sofonolime showed significant difference with Drägersorb 800 plus (P < 0.05).</p><p><b>CONCLUSION</b>The water content of sevoflurane and potassium hydroxide in CO2 absorbent can influence compound A production.</p>

A comparison between vital capacity induction and tidal breathing induction techniques for the induction of anesthesia and compound A production / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Vital capacity induction and tidal breathing induction are currently administered for inhalation induction of anesthesia with sevoflurane. The aim of this study was to compare them using sevoflurane with respect to induction time, complications of inhalation induction, and compound A production in adult patients.</p><p><b>METHODS</b>Fifty-one women with American Society of Anesthesiologists physical status I-II undergoing mammary gland tumorectomy were randomly assigned to receive either vital capacity induction or tidal breathing induction with 8% sevoflurane at 6 L/min followed by laryngeal mask airway insertion. Induction times, complications of inhalation induction, and vital signs were recorded. Inspired concentrations of compound A were assayed and sofnolime temperatures were monitored at one-minute intervals after sevoflurane administration.</p><p><b>RESULTS</b>The time to loss of eyelash reflex was significantly shorter with the vital capacity induction technique than with the tidal breathing induction technique ((43.8 ± 13.4) seconds vs. (70.8 ± 16.4) seconds, respectively; P < 0.01). Cardiovascular stability was similar in both groups. The incidence of complications was significantly less with the vital capacity induction technique than with the tidal breathing induction technique (7.7% vs. 32%, respectively; P < 0.01). However, the mean and maximum concentrations of compound A during induction were significantly higher in the vital capacity group than those in the tidal breathing group (P < 0.05); compound A concentration at the beginning of anesthesia maintenance was (40.73 ± 10.83) ppm in the vital capacity group and (29.45 ± 7.51) ppm in tidal breathing group (P = 0.019).</p><p><b>CONCLUSION</b>For inhalation induction of anesthesia, the vital capacity induction was faster and produced fewer complications than that for tidal breathing induction, but increased compound A production in the circuit system.</p>

Effect of urapidil on L-type calcium current in rat ventricular myocytes / 中华麻醉学杂志

Objective To determine the effects of urapidil on L-type calcium current(I_(Ca-L))in rat cardiomyocytes.Methods Ventricular myocytes were isolated from SD rats of either sex(250-280g)by retrograde perfusion of the hearts via aorta with calcium-free Tyrode solution containing enzyme as described elsewhere.Rod shaped cells with clear borders and striations were selected.Eighteen cells were randomly divided into 3 groups(n =6 each):A urapidil group;B urapidil+methysergide group and C methysergide group.All the cells in the three groups were peffused first with Tyrode solution for 1 min(T_1).In group A and C cells were then peffused with Tyrode solution containing 0.4 ?mol?L~(-1) urapidil(A)or 40 nmol?L~(-1) methysergide(C)for 1 min(T_2) while in group B cells were perfused fwst with Tyrode solution containing 0.4 ?mol?L~(-1) urapidil for 1 min (T_2) then with Tyrode solution containing methysergide 40 nmol?L~(-1) for 1 min (T_3).Finally the cells were again perfused with regular Tyrode solution for 1 min(T_4)to wash out the drugs.The peak of I_(Ca-L) was recorded at T_(1-4) by means of the whole cell patch clamp technique with use of Axo patch 200B.Results In group A,B and C the peak of I_(ca-L) at T_2 was significantly lower than that at T_1 but there was no significant difference between the peak of I_(ca-L) at T_1 and T_4.In group B the peak of I_(Ca-L) at T_3 was significantly lower than that at T_2.Conclusion Urapidil inhibits L-type calcium current in rat isolated cardiomyoeytes.It's inhibitory effect may not be mediated by 5-H_(1A) receptor.