Harrison G R, Critchley A D J, Mayhew C A, Thompson J M
Featherstone Department of Anaesthesia and Intensive Care, Queen Elizabeth Hospital, University Hospital Birmingham NHS Trust, Birmingham B15 2TH, UK.
Br J Anaesth. 2003 Dec;91(6):797-9. doi: 10.1093/bja/aeg271.
At present, there is no rapid method for determining the plasma concentration of i.v. anaesthetics. A solution might be the measurement of the anaesthetic concentration in expired breath and its relation to the plasma concentration. We used chemical ionization methods to determine whether an i.v. anaesthetic can be detected in the low concentrations (parts per billion by volume) in the expired breath of an anaesthetized patient.
Chemical ionization mass spectrometry can measure trace gases in air with high sensitivity without interference from major gases. We carried out a feasibility trial with a proton transfer reaction mass spectrometer (PTR-MS) to monitor the i.v. anaesthetic agent propofol and two of its metabolites in exhaled gas from an anaesthetic circuit. Exhaled gas was sampled via a 4 m long, unheated tube connected to the PTR-MS.
Propofol and its metabolites were monitored in real time in the expired breath of patients undergoing surgery.
Routine measurement of i.v. agents, analogous to that for volatile anaesthetic agents, may be possible.
目前，尚无快速测定静脉麻醉药血浆浓度的方法。一种解决方案可能是测量呼出气中的麻醉药浓度及其与血浆浓度的关系。我们使用化学电离方法来确定在麻醉患者的呼出气中是否能检测到低浓度（体积十亿分之一）的静脉麻醉药。
化学电离质谱法能够高灵敏度地测量空气中的痕量气体，且不受主要气体的干扰。我们使用质子转移反应质谱仪（PTR-MS）进行了一项可行性试验，以监测麻醉回路中呼出气体中的静脉麻醉药丙泊酚及其两种代谢产物。通过连接到PTR-MS的4米长未加热管道采集呼出气体样本。
在接受手术患者的呼出气中实时监测到了丙泊酚及其代谢产物。
类似于挥发性麻醉药，对静脉麻醉药进行常规测量或许是可行的。
