Randomization and blinding
BLIND
A research statistician used a computer to generate random numbers. The randomization code was contained in a sealed envelope. It was sent to the researcher by the research nurse the day before the surgery. An anaesthetist evaluated the suitability for inclusion of patients before surgery, recruited patients, received random codes from the researcher, then assigned patients to the two groups. The study drugs included a single dose of IVL with a concentration of 1.6 per cent (the dosage was 1.5 mg/kg, diluted to 10 ml with 0.9 per cent normal saline) and 0.9 per cent normal saline (10 ml), which were packed in containers with the same colour and packaging. Patients were randomly assigned to the lidocaine group (L group) or the normal saline group (N group) in a ratio of 1 : 1. Throughout the study, patients, researchers, anaesthetists, surgeon, nurses in the postanaesthesia nursing unit (PACU) and wards, and perioperative observation index recorders were all blind to the allocation of the study group.