Erector Spinae Block vs. Placebo Block Study

80mm 22G block needle will be inserted using an in-plane cranial to caudad approach, the needle will be advanced to target the interfascial plane deep to the erector spinae muscle at the T2 transverse process. Once the needle tip is in the correct position, 20 ml of the local anaesthetic (ropivacaine 0.5% with 1:400,000 epinephrine) will be administered slowly in 5 ml aliquots under frequent aspiration and correct spread in the interfascial plane will be observed.

Patients randomised to the Control group will then receive a sham subcutaneous injection of 0.5ml normal saline injected at the same site as the ESP block under ultrasound guidance to stimulate a real block procedure.