Emmanuel Hei-Lok Cheung1, Jonathan Chun-Hei Cheung2, Yu-Yeung Yip3. 1. ICU, North District Hospital, Hong Kong, China. Electronic address: ehlcheung@connect.hku.hk. 2. ICU, North District Hospital, Hong Kong, China. 3. Department of Anaesthesia and Intensive Care, Prince of Wales Hospital, Hong Kong, China.