Randomization
Preoperative randomization will be adopted on the day of admission. A total of 330 subjects will be allocated 1:1 to either the LMH group or the OMH group. The randomization schedule will be generated by the Clinical Trials Centre (CTC) of the principal investigator’s centre, prior to the start of the study. Stratified block randomization (block size of 10) will be used to ensure treatment allocation in equal proportions at each centre. The randomization list will be kept in a set of tamper-evident envelopes. The envelopes will be identical and sealed. The trial identifier with a sequential number will be printed on each envelope. Envelopes will be unsealed to reveal the allocation treatment 1 day prior to surgery.