Randomization and blinding
nerve block
RECRUITMENT
Eligible patients were randomized at a 1:1 ratio to be allocated to the PIFB + RSB group (20 ml 0.3% ropivacaine plus 2.5 mg dexamethasone on each side for PIFB and 15 ml 0.3% ropivacaine plus 2.5 mg dexamethasone on each side for RSB) and PIFB group (20 ml 0.3% ropivacaine plus 2.5 mg dexamethasone on each side for PIFB and 15 ml normal saline on each side for RSB) after induction of general anesthesia before incision. A randomization sequence was generated using a personal computer with a block size of 6 before recruitment by a biostatistician. Concealment was conducted using opaque, sealed envelopes. The envelopes were delivered to another researcher, and he prepared ropivacaine or normal saline. All nerve block procedures were performed by an appointed researcher, and he did not learn about what the fluid was. Anesthesiologists, patients and follow-up nurses were blinded to the group allocation. Statistical analysis was performed by another researcher who was blinded to allocation.