呼吸前反馈调节、情景想象和过度通气

通过大量的科学证据 ,我们论述了代谢的负反馈调节不是呼吸调节的唯一机制。醒觉时呼吸的前反馈调节起了主导作用 ,前反馈调节可以在血气异常引起的负反馈调节之前 ,对将要发生的异常进行纠正 ,预见性地改变通气 ,而代谢的变化随后发生 ,避免了负反馈调节所具有的波动和滞后的缺点 ,使呼吸调节系统具有更大的灵活性和适应能力。在前反馈调节的形成过程中 ,经典的巴甫洛夫条件反射学说可能起了重要作用 .尤其重要的是表象作为条件刺激形成的条件反射 ,研究表象作为条件刺激如何形成呼吸的前反馈调节对揭示高通气综合征的发病机制具有重要意义…     

The comparison of high and standard definition computed tomography techniques regarding coronary artery imaging

ObjectiveThe aim was to compare coronary high-definition CT (HDCT) with standard-definition CT (SDCT) angiography as to radiation dose, image quality and accuracy.ResultsThe intraclass correlation coefficient (ICC) of measured vessel attenuation values in SDCT between the two radiologists was exceedingly good. The ICC was higher in HDCT. The radiation dose of HDCT was higher than that of SDCT. The mean tube current was 180 (mA) in HDCT and 147(mA) in SDCT with the same tube voltage (kVp). There was no significant difference between image quality.ConclusionHDCT has a higher radiation dose but has much more atenuation and the spatial resolution which improve measurement accuracy for imaging coronary arteries.