Huaiwu He1, Yun Long2, Inéz Frerichs3, Zhanqi Zhao4. 1. Department of Critical Care Medicine, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Science, Beijing, China. 2. Peking Union Medical College Hospital, 34732, Dongcheng-qu, China; iculong_yun@163.com. 3. University Medical Centre Schleswig-Holstein, Department of Anaesthesiology and Intensive Care Medicine, Kiel, Germany. 4. Furtwangen University, Institute of Technical Medicine, Villingen-Schwenningen, Germany.