Background. The inhibitory effect of anaesthetic agents on hypoxic pulmonary vasoconstriction may depend upon their dose, especially when using a volatile agent. The aim of this randomized open study was to compare the effects of sevoflurane and propofol, as primary anaesthetic agents, on oxygenation during one-lung ventilation (OLV), with their administration being adjusted to maintain bispectral index (BIS) values between 40 and 60.

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Background Anesthesia for rigid bronchoscopic procedures is a demanding procedure. Automatic titration of propofol and remifentanil to maintain the bispectral index (BIS) within the recommended range (40-60) has been reported during routine surgical procedures. The aim of the present study was to evaluate its use during rigid bronchoscopy. Methods Patients were enrolled in a randomized study comparing manual target-controlled infusion of propofol and remifentanil (manual TCI group) with automatic titration guided by the BIS (dual-loop group). Categorical variables were compared by the Fisher's exact test, and continuous variables (median [interquartile range 25-75]) were compared by the Mann-Whitney test. Results Thirty-four patients were included in the manual TCI group and 33 were included in the dual-loop group. Baseline characteristics were well balanced between the groups. Intervention by the anesthesiologist in charge to modify propofol and/or remifentanil targets in the dualloop group was not necessary. Percentage of time spent in the BIS interval (40-60) was similar in the manual TCI and dual-loop groups (69% [48-79] vs 70% [58-80], respectively). Durations of induction and of maintenance and propofol and remifentanil doses were also similar between groups, except for the amount of propofol needed for induction (P = 0.002). Time to tracheal extubation was also similar. No case of intraoperational awareness was detected. Conclusion The present study could not establish the superiority of automatic system over manual adjustment for bronchoscopy. Further studies with a different design and a larger number of patients are required to establish the place of automatic delivery of anesthetic agents. This Author contributions Ngai Liu and Marc Fischler made substantial contributions to the conception and design of the study. Ngai Liu, Thierry Chazot, and Bernard Trillat made substantial contributions to the analysis of data. Ngai Liu and Thierry Chazot made substantial contributions to the interpretation of data.