Comparison of postoperative analgesic efficacy between bilateral ultrasound guided Retrolaminar block and local anaesthetic infiltration in patients undergoing Thoraco-lumbar spine surgery – a double blinded prospective randomized controlled trial

The study will be conducted in Trama Emergency OT, Orthopaedics Elective OT and Neurosurgery Elective OT in Trauma Centre, Institute of Medical Sciences, BHU, Varanasi. After approval from hospital research and ethical committee, a double blinded prospective Randomized study will be conducted on patients coming to IMS, BHU, Varanasi. Once the patients are enrolled, they will be randomized into either Group R or Group L. Randomization will be done using computer generated random number sequence. Allocation concealment will be done using serially numbered opaque sealed envelopes. The process of allocation will be done by a staff member who is not a part of the study group. There will be 68 such sealed opaque envelopes pre-designed with equal numbers of Retrolaminar block and local anaesthetic infiltration. One day prior to the scheduled surgery, all the patients will be instructed on how to evaluate their own pain by using a 10cm Numeric rating pain scale( 0-no pain, 10-maximum pain). In the

operating room after attaching the standard ASA monitors and IV lines, the patient will be induced using standardized general anaesthesia protocol as routinely followed in our department. IV induction along with muscle relaxation followed by endotracheal intubation will be done using appropriate size cuffed tube. Mechanical Ventilation will be established with an oxygen-air mixture and titrated to ETCO2 between 35 to 45 mm Hg. Analgesia maintained with Inj. Fentanyl 2mcg/kg at induction given for all patients. Maintenance of anaesthesia will be done using inhalation agent Isoflurane and intermittent muscle relaxant as required. Fluid therapy will be provided according to routine institutional practice. Inj. Dexamethasone 0.1mg/kg IV will be given to all patients at the start of surgery. Inj. Diclofenac 75 mg iv will be given to all patients prior to skin incisions. If MAP or HR is more than equal to 20% from baseline, ruling out hemodynamic causes or insufficient depth of anaesthesia, Inj. Fentanyl 0.5 mcg/kg will be given for intraoperative pain management. Patients will be turned to prone position taking care of endotracheal tube, pressure points, eye, spine and possible nerve injuries.

Group R (Retrolaminar Group): Before the incision, the intervention area will be sterilized with povidone iodine and spirit before the procedure, covered by sterile drapes and a sterile sheath will be applied to the ultrasound probe. High frequency linear or curved array probe is selected depending on the patient’s body habitus and depth of the vertebral lamina. The ultrasound probe will be placed sagittally in the midline at the target vertebral level, i.e., intermediate one for surgical level(s) of odd number or the upper or second one for surgical levels of even number. After the spinous processes are seen, the ultrasound probe is moved laterally 1-2 cm and vertebral lamina are observed. A 5-10 cm 22G stimuplex needle is inserted in real time in cranial to caudal direction with in plane technique. When the needle touches the lamina, Inj. Ropivacaine 0.2% 20ml is administered with low pressure. The same intervention will be performed on the other side of the vertebral lamina.

Group L (Local anaesthetic infiltration group): Wound infiltration will be performed by the surgeon at the end of the surgery. After hemostasis achieved and before skin closure, 40 mL of 0.20% ropivacaine will be infiltrated into multiple layers of the surgical wound, in prone position. This will include the subcutaneous tissue and muscle layers, ensuring the even distribution of the anesthetic solution to cover the entire surgical area. Inj. Paracetamol 1 gm iv will be given to all patients 15 min, before skin closure. At the end of surgery, Inj. Ondansetron 0.1mg/kg will be given and muscle relaxation will be reversed with Inj. Neostigmine 50 mcg/kg and Inj. Glycopyrrolate 10mcg/kg. The patient will be extubated and the patients will be transferred to Post-Anaesthesia care unit.

Once the patients are transferred into wards, all will receive round the clock Inj. Paracetamol 1 gm IV 8 hourly and Inj. Diclofenac 75 mg 12 hourly. For rescue analgesia (when the NRS score will be more than 3) in postoperative period, Inj. Tramadol 1mg/kg will be given. The duration of analgesia will be from administration of block to the first use of rescue analgesia. Total consumption of Inj. Tramadol as rescue analgesic will be recorded in the 24 hour observation period. Incidence of Side Effects: nausea, vomiting and surgical site infection will be recorded as binary outcomes (present/absent). The total length of hospital stay will also be recorded (starting from the day of surgery which will be taken as Day 0).