LF, HF, LF/HF, SBP and HR were monitored respectively at the follow intervals: before or during controlled hypotension, and after SBP restoration.

• 记录降压前、降压过程中及复压前后低频(LF)、高频(HF)、低高频比值(LF/HF)及收缩压(SBP)、心率(HR)。