T Perl1, E Carstens, A Hirn, M Quintel, W Vautz, J Nolte, M Jünger. 1. Department of Anaesthesiology, Emergency and Intensive Care Medicine, University of Göttingen, Göttingen, Germany. tperl@med.uni-goettingen.de
Abstract
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 microg 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 microg 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.
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 microg 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 microg 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.