Simultaneous on-line monitoring of propofol and sevoflurane in balanced anesthesia by direct resistive heating gas chromatography.

In balanced anesthesia, sevoflurane and propofol are often used in combination to achieve a better anesthetic effect. However, methods for on-line monitoring of concentrations of the two anesthetics in patients are still rare in clinical. This study proposed a non-invasive method utilizing a fast gas chromatograph combined with a surface acoustic wave sensor (Fast GC-SAW) to simultaneously on-line monitor sevoflurane and propofol in patients' exhaled gas. By using the direct resistive heating capillary column, the single detection time of Fast GC-SAW system was significantly shortened to 90s, as well as the size reduced to (40cm×30cm×20cm). Besides, in the calibration of sevoflurane, Fast GC-SAW system showed a good linear correlation (R=0.9925, P<0.01) with gas chromatography-mass spectrometer (GC-MS), which ensured the reliability and accuracy of the Fast GC-SAW system. Finally, clinical experiments on patients under balanced anesthesia were conducted. The varied concentrations measured by Fast GC-SAW extraordinarily matched the clinical usages of these two anesthetics.