From the Department of Anesthesiology and Perioperative Medicine, Zhengzhou Central Hospital Affiliated to Zhengzhou University, Zhengzhou, Henan, China (G-YY) Correspondence to Guan-Yu Yang, Zhengzhou Central Hospital Affiliated to Zhengzhou University, Tongbai North Road 16, Zhongyuan District, Zhengzhou 450007, China Tel: +86 15738314002; e-mail: [email protected]