Cognitive function and delirium following sevoflurane or propofol anesthesia for valve replacement surgery: A multicenter randomized controlled trial oleh Guang‐You Duan, Zhen‐Xin Duan, Hong Chen, Feng Chen, Fang Chen, Zhi‐Yong Du, Li‐Yong Chen, Kai‐Zhi Lu, Zhi‐Yi Zuo, Hong Li