Determination of serum propofol concentrations by breath analysis using ion mobility spectrometry

Background We aimed to measure propofol concentrations in exhaled air with an ion mobility spectrometer coupled to a multicapillary column for pre-separation (MCC–IMS). In addition, we aimed to compare the values of these measurements with serum propofol concentrations, as determined by gas chromatography–mass spectrometry (GC–MS). Methods Thirteen patients, ASA I or II, undergoing elective ENT surgery were studied. Anaesthesia was induced with propofol 2.1 (0.7) mg kg −1 , rocuronium 0.5 (0.1) mg kg −1 , and remifentanil 0.5 µg kg −1 min −1 . After tracheal intubation, anaesthesia was maintained with a continuous infusion of propofol 3.9 (1.8) mg kg −1 h −1 and remifentanil 0.5 µg kg −1 min −1 . Simultaneously, a venous blood sample was obtained. Propofol concentrations in serum were determined by GC–MS and compared with the height of the respective propofol signals achieved by MCC–IMS. Results Twenty-four pairs of samples were obtained. The comparison of propofol concentrations in exhaled air and serum presented a bias of −10.5% and a precision of ± 12.3%. With these values, the 95% limits of agreement were 14.1% and −35.1%. Conclusions MCC–IMS may be a suitable method to determine propofol concentrations in exhaled air, and may be used to predict propofol concentrations in serum.