BackgroundAn anesthetic state can reduce adverse airway reaction during laryngeal mask airway (LMA) removal in children. However, the anesthetic state has risks of upper airway obstruction or delayed emergence; so possibly less anesthetic depth is advisable. Caudal analgesia reduces the requirement of anesthetic agents for sedation or anesthesia; it is expected to reduce the sevoflurane requirement for LMA removal. Therefore, we determined the EC50 of sevoflurane for LMA removal with caudal analgesia and compared that to the EC50 without caudal analgesia.MethodsForty-three unpremedicated children aged 1 to 6 yr were enrolled. They were allocated to receive or not to receive caudal block according to their parents' consent. General anesthesia were induced and maintained with sevoflurane and oxygen in air. EC50 of sevoflurane for a smooth LMA removal with and without caudal analgesia were estimated by the Dixon up-and-down method. The LMA was removed when predetermined end-tidal sevoflurane concentration was achieved, and the sevoflurane concentration of a subsequent patient was determined by the success or failure of the previous patient with 0.2% as the step size; success was defined by the absence of an adverse airway reaction during and after LMA removal. EC50 of sevoflurane with caudal block, and that without caudal block, were compared by a rank-sum test.ResultsThe EC50 of sevoflurane to achieve successful LMA removal in children with caudal block was 1.47%; 1.81% without caudal block. The EC50 were significantly different between the two groups (P < 0.001).ConclusionsCaudal analgesia significantly reduced the sevoflurane concentration for a smooth LMA removal in anesthetized children.

Pyrophosphoric lactone-modified polyester containing two phosphorous functional groups in one structural unit of base resin was synthesized to prepare a nontoxic, reactive flame-retardant coatings. Then, the pyrophosphoric lactone-modified polyester was cured at room temperature with isocyanate and isophorone diisocyanate (IPDI)-isocyanurate to get a two-component polyurethane flame-retardant coatings (TAPPU). Comparing the physical properties of the films of TAPPU with the film of nonflame-retardant coatings, no deterioration of physical properties was observed with the incorporation of a flame-retarding component into the resin. Three kinds of flame retarding tests were conducted, including the 45°Meckel burner method, limiting oxygen index method (LOI method), and oxygen combustion method with Cone calorimeter. It was observed that the char lengths were 3.1ϳ4.5 cm and LOI values were 27ϳ30%. These results indicate that the prepared coatings are good flame-retardant ones. It was also found that the flame retardancy of those coatings was increased with the contents of phosphorous.

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