*Department of Critical Care Medicine, First People's Hospital of Xuzhou, Xuzhou Municipal Hospital Affiliated to Xuzhou Medical University, Affiliated Hospital of Mining and Technology of China University, Xuzhou, Jiangsu, China;

†Department of Thoracic Surgery, Xuzhou Central Hospital, Xuzhou, Jiangsu, China;

‡Department of Orthopedics, First People's Hospital of Xuzhou, Xuzhou Municipal Hospital Affiliated to Xuzhou Medical University, Affiliated Hospital of Mining and Technology of China University, Xuzhou, Jiangsu, China;

§Department of Ophthalmology, First People's Hospital of Xuzhou, Xuzhou Municipal Hospital Affiliated to Xuzhou Medical University, Affiliated Hospital of Mining and Technology of China University, Xuzhou, Jiangsu, China;

¶Department of Hemodialysis, First People's Hospital of Xuzhou, Xuzhou Municipal Hospital Affiliated to Xuzhou Medical University, Affiliated Hospital of Mining and Technology of China University, Xuzhou, Jiangsu, China;

║Department of Anesthesiology, Xuzhou Cancer Hospital, Xuzhou City, Jiangsu Province, China;

**Department of Anesthesiology, Xuzhou New Healthy Geriatric Hospital, Xuzhou City, Jiangsu Province, China; and

††Department of Anesthesiology, the Affiliated Xuzhou Hospital of JiangSu University, Xuzhou City, Jiangsu Province, China.

Correspondence: Lei Heng, MD, Department of Anesthesiology, Xuzhou Cancer Hospital, Xuzhou, Jiangsu 221005, China (e-mail: [email protected]).

Supported by grants KC19148 from the Science and Technology Bureau of Xuzhou.

The authors report no conflicts of interest.

L. Li, M. Liu, S. S. Li and J. H. Xu carried out the studies, participated in collecting data, and drafted the manuscript. L. Heng performed the statistical analysis and participated in its design. J. Zheng, C. W. Lv and L. L. Wu helped to draft the manuscript. All authors read and approved the final manuscript.

L. Li, M. Liu, S. Li, and J. Xu have contributed equally.