Shaw A D, Chamberlain S K, Spased-Byrne S M, Lockwood G G
Department of Anaesthesia, Imperial College School of Medicine, Hammersmith Hospital, London, United Kingdom.
Anesth Analg. 1998 Dec;87(6):1412-5. doi: 10.1097/00000539-199812000-00039.
Nitrous oxide (N2O) has been shown to decrease the solubility (lambdaB:G) of volatile anesthetics in human blood and, consequently, affect their rate of uptake. If this is true, then carbon dioxide (CO2) may also have an effect, which is important because methods that measure the tension of volatile anesthetics in blood washout CO2 in the process. Blood samples were obtained from fasted, healthy volunteers and patients undergoing major surgery. Each sample was divided into two aliquots: one was equilibrated at 37 degrees C in a closed glass tonometer with a mixture of isoflurane 1% and sevoflurane 2% in a test gas mixture of either 50:50 N2O/O2 or 5:95 CO2/O2; the other aliquot was equilibrated with isoflurane and sevoflurane in O2 alone as a control. Using a two-stage headspace technique using gas chromatography, we measured the lambdaB:G of isoflurane and sevoflurane in the presence and absence of the test gas in each subject. There was no significant difference between the lambdaB:G of sevoflurane and isoflurane obtained from the N2O group and their controls or between the CO2 group and their controls. We conclude that neither N2O nor CO2 has an effect on the lambdaB:G of sevoflurane or isoflurane in the concentrations tested.
The blood solubilities of sevoflurane and isoflurane were measured with and without nitrous oxide and carbon dioxide. No differences were found. Nitrous oxide does not affect the kinetics of other anesthetics by altering their solubility. Carbon dioxide tensions need not be controlled when measuring anesthetic tensions in blood.
一氧化二氮（N₂O）已被证明可降低挥发性麻醉剂在人血液中的溶解度（λB:G），因此会影响其摄取速率。如果情况确实如此，那么二氧化碳（CO₂）可能也会有影响，这一点很重要，因为在测量血液中挥发性麻醉剂张力的过程中会洗出CO₂。从禁食的健康志愿者和接受大手术的患者身上采集血样。每个样本分成两份：一份在封闭的玻璃压力计中于37℃下与含有1%异氟烷和2%七氟烷的混合气体平衡，该混合气体存在于50:50 N₂O/O₂或5:95 CO₂/O₂的测试气体混合物中；另一份作为对照，仅与O₂中的异氟烷和七氟烷平衡。使用气相色谱的两步顶空技术，我们测量了每个受试者在有和没有测试气体存在的情况下异氟烷和七氟烷的λB:G。从N₂O组获得的七氟烷和异氟烷的λB:G与其对照之间或CO₂组与其对照之间没有显著差异。我们得出结论，在所测试的浓度下，N₂O和CO₂对七氟烷或异氟烷的λB:G均无影响。
在有和没有一氧化二氮及二氧化碳的情况下测量了七氟烷和异氟烷的血液溶解度。未发现差异。一氧化二氮不会通过改变其他麻醉剂的溶解度来影响其动力学。在测量血液中的麻醉剂张力时无需控制二氧化碳张力。
