Department of Anaesthesiology, Klinikum der Universität, Ludwig-Maximilians-University Munich, Munich, Germany.
Anal Bioanal Chem. 2012 Apr;403(2):555-61. doi: 10.1007/s00216-012-5856-3. Epub 2012 Feb 28.
Propofol in exhaled breath can be detected and monitored in real time by ion molecule reaction mass spectrometry (IMR-MS). In addition, propofol concentration in exhaled breath is tightly correlated with propofol concentration in plasma. Therefore, real-time monitoring of expiratory propofol could be useful for titrating intravenous anesthesia, but only if concentration changes in plasma can be determined in exhaled breath without significant delay. To evaluate the utility of IMR-MS during non-steady-state conditions, we measured the time course of both expiratory propofol concentration and the processed electroencephalography (EEG) as a surrogate outcome for propofol effect after an IV bolus induction of propofol. Twenty-one patients scheduled for routine surgery were observed after a bolus of 2.5 mg kg(-1) propofol for induction of anesthesia. Expiratory propofol was measured using IMR-MS and the cerebral propofol effect was estimated using the bispectral index (BIS). Primary endpoints were time to detection of expiratory propofol and time to onset of propofol's effect on BIS, and the secondary endpoint was time to peak effect (highest expiratory propofol or lowest BIS). Expiratory propofol and changes in BIS were first detected at 43 ± 21 and 49 ± 11 s after bolus injection, respectively (P = 0.29). Peak propofol concentrations (9.2 ± 2.4 parts-per-billion) and lowest BIS values (23 ± 4) were reached after 208 ± 57 and 219 ± 62 s, respectively (P = 0.57). Expiratory propofol concentrations measured by IMR-MS have similar times to detection and peak concentrations compared with propofol effect as measured by the processed EEG (BIS). This suggests that expiratory propofol concentrations may be useful for titrating intravenous anesthesia.
呼气中丙泊酚可以通过离子-分子反应质谱（IMR-MS）实时检测和监测。此外，呼气中丙泊酚浓度与血浆中丙泊酚浓度密切相关。因此，实时监测呼气中的丙泊酚浓度对于滴定静脉麻醉可能是有用的，但前提是呼气中丙泊酚浓度的变化可以在没有明显延迟的情况下在血浆中得到确定。为了评估 IMR-MS 在非稳态条件下的效用，我们测量了呼气中丙泊酚浓度和处理后的脑电图（EEG）的时间过程，作为静脉注射丙泊酚诱导麻醉后丙泊酚效应的替代结果。21 名计划接受常规手术的患者在静脉注射 2.5mg/kg 的丙泊酚诱导麻醉后接受观察。使用 IMR-MS 测量呼气中的丙泊酚浓度，并使用双谱指数（BIS）估计脑内丙泊酚效应。主要终点是呼气中丙泊酚检测时间和 BIS 上丙泊酚作用开始时间，次要终点是峰效应时间（呼气中丙泊酚最高或 BIS 最低）。在推注后 43 ± 21 秒和 49 ± 11 秒分别首次检测到呼气中的丙泊酚和 BIS 的变化（P = 0.29）。达到最高的丙泊酚浓度（9.2 ± 2.4 十亿分之几）和最低的 BIS 值（23 ± 4）的时间分别为 208 ± 57 秒和 219 ± 62 秒（P = 0.57）。IMR-MS 测量的呼气中丙泊酚浓度与经过处理的 EEG（BIS）测量的丙泊酚效应的检测时间和峰值浓度相似。这表明呼气中的丙泊酚浓度可能有助于滴定静脉麻醉。
