This study will be carried out in Department of Anesthesiology & Critical care AIIMS Jodhpur after institution ethical approval.

Inclusion Criteria

·         Patients belonging to American Society of Anesthesiologists (ASA) physical status grade I or II aged between 18 to 60 years scheduled to undergoing VAT surgeries.

Exclusion Criteria

1.      Patient refusal

2.      Preexisting infection at block site

3.      Coagulation Disorder

4.      History of psychiatric illness and preexisting neurological deficits

5.      Patient with morbid obesity BMI >40 kg/ m2

6.      Decreased pulmonary reserve, cardiac disorders and renal dysfunctions

7.      Known allergy to study drugs

8.      Presence of any preoperative pain or history of chronic pain

9.      History of regular analgesic use

During the preoperative visit a day before surgery, all patients will thoroughly explained about the procedure. They will also made well conversant about visual analogue score (VAS 0–10, 0= no pain, 10= worst pain). Patients will be randomly allocated by using computer generated random number method into two groups in 1:1 allocation ratio. The group allocation numbers will be concealed in sealed opaque envelopes that will be opened just before the performance of block. Group conventional (CP) group patients will receive TPVB at T4 level by conventional approach, whereas Group modified (MP) technique patients will receive TPVB by MTP approach at T4 level unilaterally on the operative side. In both groups block will be performed under ultrasound guidance and receive 20 ml 0.2% ropivacaine.

     In the procedure room, routine monitors will be attached and baseline vitals recorded. All the patients will receive premedication with intravenous (IV) midazolam (0.04–0.06 mg/kg) and fentanyl (1µg/kg) IV.

Conventional approach of thoracic PVB - TPVB will be administered at the T4 level on the side of surgery with the patient in the sitting position. The high frequency ultrasound probe (LOGIQe, GE Healthcare, China) will be placed 3-4cm from the midline in the cephalad-caudal direction and identify the transverse process, parietal pleura and superior costotransverse ligament (SCTL). The skin will be infiltrated with 2% lidocaine followed by ropivacaine 0.2%, 20 ml will be deposited in paravertebral space  by block needle (8 cm Contiplex, B Braun) after piercing   of SCTL and then catheter will be inserted in the paravertebral space 3 cm distal to needle tip. After insertion of catheter, infusion (0.2% ropivacaine) at the rate of 0.1ml/kg/hr will continued throughout intraoperative period.

MTP approach of thoracic PVB-MTP block will be performed at T4 level on the operative side by using high frequency ultrasound probe (LOGIQe, GE Healthcare, China) with parasagittal scan, in-plane technique and with needle direction from caudal to cephalic. Local anesthetic will be deposited at the mid-point between the posterior border of the transverse process and the pleura (superficial to the SCTL). A total of 20 ml of 0.2% ropivacaine will be injected, followed by catheter insertion 3 cm distal to needle tip. After insertion of catheter, infusion (0.2% ropivacaine) at the rate of  0.1ml/kg/hr will continued throughout intraoperative period.

Assessment of block: postoperative fentanyl requirement will be noted and if more than 2 doses of fentanyl at the rate of 1 mcg/ kg is required in consecutive 4 hours than it will be labeled as block failure

Anesthetic technique: After arrival in the operation theatre, routine monitoring will be continued. Following pre-oxygenation, anesthesia will be induced with fentanyl 2 mcg/kg and propofol 2 mg/kg and rocuronium 0.5 mg/kg and an appropriate sized endotracheal tube will be inserted. Maintenance of anesthesia will be achieved with isoflurane in oxygen and air mixture (MAC 0.8-1.0). Heart rate (HR), oxygen saturation (SpO₂)and mean blood pressure (MBP) will be continuously monitored throughout the surgery.  Ondansetron 4mg IV will be administered as prophylactic antiemetic to all patients. At the end of surgery, all patients will be reversed as per usual protocol. The patients will be shifted to post anesthesia care unit (PACU) and further to ward and will be monitored at regular intervals for 24 h after surgery.

Complications related to procedure or drugs used will be recorded (pneumothorax, local anesthetic toxicity )

Postoperative pain intensity will be measured using VAS (1–10) at 1, 3, 6, 12, 18 and 24 h by an independent observer who is not known about study group. Injection fentanyl 1 mcg/kg will be used as rescue analgesic, if VAS score ≥4 is recorded or on patient demand.  Time to first rescue analgesia and total amount of analgesics used in 24 h postoperatively will be recorded.

.At 24 h after surgery, satisfaction of the patients will be assessed using a numerical satisfaction score as 4= excellent, 3=good, 2=fair, 1=poor.