Dose-response and concentration-response relation of rocuronium infusion during propofol nitrous oxide and isoflurane nitrous oxide anaesthesia

The dose-response and concentration-response relation of rocuronium infusion was studied in 20 adult surgical patients during proporfol-nitrous oxide and isoflurane (1 MAC) -nitrous oxide anaesthesia. Neuromuscular block was kept constant, initially at 90% and then at 50% with a closed-loop feedback controller. At 90% block the steady-state infusion of rocuronium was 0.55 +/- 0.16 mg kg(-1) h(-1) and the corresponding concentration 1714 +/- 281 ng mL(-1) in patients receiving propofol. At 50% block the corresponding infusion rate was 0.27 +/- 0.11 mg kg(-1) h(-1) and the concentration 1077 +/- 244 ng mL(-1), respectively. At 50% block isoflurane reduced the rate of infusion by 52% (P <0.005) and the concentration by 59% (P <0.001); at 90% block both the mean infusion rate and the concentration of rocuronium were reduced by 35% (P <0.005). The mean rocuronium clearance at 50% block was unaffected by the type of anaesthesia; it was 4.1 +/- 1.6 and 4.9 +/- 2.7 mL kg(-1) min(-1) in the groups receiving propofol and isoflurane anaesthesia, respectively. We conclude that isoflurane reduces the infusion requirements of rocuronium by changing the pharmacodynamic behaviour

X-ray microtomography and laser ablation in the analysis of ink distribution in coated paper

A novel method was developed for studying the ink-paper interface and the structural variations of a deposited layer of ink. Combining high-resolution x-ray tomography with laser ablation, the depth profile of ink (toner), i.e., its varying thickness, could be determined in a paper substrate. X-ray tomography was used to produce the 3D structure of paper with about 1 lm spatial resolution. Laser ablation combined with optical imaging was used to produce the 3D structure of the printed layer of ink on top of that paper with about 70 nm depth resolution. Ablation depth was calibrated with an optical profilometer. It can be concluded that a toner layer on a light-weight-coated paper substrate was strongly perturbed by protruding fibers of the base paper. Such fibers together with the surface topography of the base paper seem to be the major factors that control the leveling of toner and its penetration into a thinly coated paper substrate.peerReviewe