Lu Chih-Cherng, Ho Shung-Tai, Wang Jhi-Joung, Wong Chih-Shung, Hu Oliver Yao-Pu, Chang Sun-Yran, Lin Chung-Yuan
Department of Anesthesiology, Tri-Service General Hospital, National Defense Medical Center, No. 161, Section 6 Minchuan E. Road, Taipei, Taiwan.
Pharmacology. 2003 Oct;69(2):102-7. doi: 10.1159/000072363.
We studied the effect of the inspired isoflurane concentration (C(I)iso) on the pharmacokinetics of isoflurane uptake in the brain by comparing the isoflurane concentration in internal jugular-bulb blood (Jiso) with that in arterial blood (Aiso), and analyzed this by gas chromatography. Sixteen patients (aged 43-76 years) undergoing colorectal surgery were enrolled, and anesthesia was maintained with a constant C(I)iso of either 1% (group 1, n = 8) or 2% (group 2, n = 8) during the 1st hour of isoflurane anesthesia. Under constant volume-controlled ventilation, we measured the C(I)iso and the end-tidal isoflurane concentration (C(E)iso) at the mouthpiece by infrared analysis. Our results demonstrate that it takes 40 min for the brain tissue concentration to equal Aiso for 1% C(I)iso, and 50 min for 2% C(I)iso. The Aiso (and/or Jiso) for 2% C(I)iso was approximately double when compared to that for 1% C(I)iso. Except during the initial wash-in period of the functional residual capacity in the first 3 min, the differences between C(I)iso and C(E)iso revealed that the body uptake of isoflurane for 2% C(I)iso was twice that for 1% C(I)iso. These results demonstrate that the pharmacokinetics of isoflurane uptake in the brain is time-dependent for Jiso to equal Aiso, and the midpoint between Aiso and Jiso (likely representing the isoflurane concentration in brain tissue) was dependent on C(I)iso.
我们通过比较颈内静脉球部血液中的异氟烷浓度（Jiso）与动脉血中的异氟烷浓度（Aiso），研究了吸入异氟烷浓度（C(I)iso）对异氟烷在脑内摄取的药代动力学的影响，并通过气相色谱法进行分析。纳入16例接受结直肠手术的患者（年龄43 - 76岁），在异氟烷麻醉的第1小时内，以1%（第1组，n = 8）或2%（第2组，n = 8）的恒定C(I)iso维持麻醉。在恒定容量控制通气下，我们通过红外分析测量了C(I)iso和接口处的呼气末异氟烷浓度（C(E)iso）。我们的结果表明，对于1%的C(I)iso，脑组织浓度达到Aiso需要40分钟，对于2%的C(I)iso则需要50分钟。与1%的C(I)iso相比，2%的C(I)iso时的Aiso（和/或Jiso）约为两倍。除了最初3分钟功能残气量的初始冲洗期外，C(I)iso和C(E)iso之间的差异表明，2%的C(I)iso时异氟烷的机体摄取量是1%的C(I)iso时的两倍。这些结果表明，异氟烷在脑内摄取的药代动力学在Jiso等于Aiso时是时间依赖性的，并且Aiso和Jiso之间的中点（可能代表脑组织中的异氟烷浓度）取决于C(I)iso。
