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Different anesthetic techniques have been suggested for craniotomy with intraoperative awakening. We describe an asleep-awake-asleep technique with propofol and remifentanil infusions, with pharmacokinetic simulation to predict the effect-site concentrations and to modulate the infusion rates of both drugs, and bispectral index (BIS) monitoring. Five critical moments were defined: first loss of consciousness (LOC 1 ), first recovery of consciousness (ROC 1 ), final of neurologic testing (NT), second loss of consciousness (LOC 2 ), and second recovery of consciousness (ROC 2 ). At LOC 1 , predicted effect-site concentrations of propofol and remifentanil were, respectively, 3.6±1.2 μg/mL and 2.4±0.4 ηg/mL. At ROC 1 , predicted effect-site concentrations of propofol and remifentanil were, respectively, 2.1±0.3 μg/mL and 1.8±0.3 ηg/mL. At NT, predicted effect-site concentrations of propofol and remifentanil were, respectively, 0.9±0.3 μg/mL and 1.8±0.2 ηg/mL. At LOC 2 , predicted effect-site concentrations of propofol and remifentanil were, respectively, 2.1±0.2 μg/mL and 2.5±0.2 ηg/mL. At ROC 2 , predicted effect-site concentrations of propofol and remifentanil were, respectively, 1.2±0.5 μg/mL and 1.4±0.2 ηg/mL (data are mean±SE). A significative correlation was found between BIS and predicted effect-site concentrations of propofol (r 2 =0.547, P<0.001) and remifentanil (r 2 =0.533, P<0.001). Multiple regression analysis between BIS and propofol and remifentanil predicted effect-site concentrations at the different critical steps of the procedure was done and found also significative (r 2 =0.7341, P<0.001).

Clinicians should be aware of the several limitations of the commercial devices intending to monitor the depth of anaesthesia, which may not reflect the real underlying level of unconsciousness.

The survey will help us learn more about different practice models for anesthesia training delivery in low-and middle-income countries (LMICs), focusing on non-physician anaesthesia providers. We are inviting participants who provide or have personal knowledge of anesthesia or surgery care in LMICs, and we have contacted you through word of mouth or national societies.

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Leaf gas exchange, water potential, and specific leaf area of two tropical semi-deciduous tree species, Brosimum lactescens S. Moore and Tovomita schomburgkii Planch & Triana, were quantified to establish how these properties were affected by seasonal variations in rainfall and leaf canopy position. The study was conducted at a site near Sinop Mato Grosso, Brazil, which is located within the ecotone of savanna and tropical rain forest. Both species exhibited significant declines in leaf water potential (Ψ L ), specific leaf area, area-and mass-based light saturated photosynthesis and dark respiration, and maximum stomatal conductance during the dry-season, suggesting that leaf structural properties and gas exchange are significantly altered by drought that develops during the 4-month dry season. Internal leaf CO 2 concentrations (C i ) were consistently lower during the dry season suggesting that the decline in maximum photosynthesis was due in part to a decline in stomatal conductance. However, seasonal variations in leaf gas exchange were larger for upper-canopy leaves, indicating an important interaction between drought stress and canopy position. The seasonal variation in leaf gas exchange and morphology was presumably due to a combination of drought stress and leaf lifespan. The results of this study suggest that drought has important implications for the leaf physiology and morphology of semi-deciduous Amazonian forest trees.