All selected patients will undergo a routine preanesthetic assessment with one day prior to surgery. All patients will be explained about the blocks and study methodology, including the advantages of postoperative pain relief. The patient information sheet will be provided to all, and informed written consent from all patients will be obtained. Patients will be taught to express pain by using a 11-point NRS (Numeric Rating Scale), in which they will be asked to encircle a number between 0 and 10 that would fit best to their pain intensity other where 0 represents ‘no pain at all’ and ten means ‘worst pain ever possible’. Patient will be trained and counselled regarding functioning and operability of the PCA pump during the preanesthetic visit.

            Standard fasting guidelines [WHO] will be followed for all patients. All patients will be premedicated with Tab Alprazolam 0.25mg orally the night before the day of surgery. On the day of surgery, the Anaesthesia Machine will be thoroughly checked, and the availability of appropriate airway equipment will be ensured.

              Baseline parameters, heart rate, non-invasive blood pressure (NIBP), oxygen saturation (SpO2), and respiratory rate (RR) will be recorded before the anaesthetic induction. Patients will be allotted to one of the two groups depending on a computer-generated random number table. Allocation concealment will be ensured by enclosing assignments in sealed, opaque, sequentially numbered envelopes, which will be opened only upon the patient’s arrival in the operation room.

             Both the regional blocks will be performed by the investigator before induction and the patient will not know about the type of intervention and an anaesthesiologist blinded to the study groups will be responsible for postoperative follow up. Hence, it will be conducted as a double blind study.

           Both the blocks will be performed in pre anesthesia room with facilities of monitoring and oxygen. Intravenous access will be secured. Patients will be in sitting position with neck slightly flexed and back arched towards the operator. Same position will be employed for the conduct of regional block. The block will be performed at T4 level using 15ml of  0.375% Ropivacaine.

         The intervention will be carried out using the ( Sonosite Edge , Sonosite , Inc, Bothell, WA) ultrasound machine placed on the right side of the patient and the investigator will be performing by standing on the left side of the patient. A linear transducer (5-12 MHz) will be used and transducer will be covered using a sterile sheath. Both the  blocks will be performed under aseptic precautions, parts will be sterilized using chlorhexidine and draped, exposing the area of intervention. An echogenic , 80-mm, 22- gauge block needle ( Pajunk SonoTAP, Geisingen , Germany).

GROUP 1: USG-TPVB

               The high frequency(5-12MHz) linear transducer probe will be oriented in identifying the the spinous process of  T2 to T6. After identifying the T4 vertebrae, the probe is placed 2.5 cm lateral to the T4 spinous process. The transverse processes and ribs are visualized as hyperechoic structures with acoustic shadowing below them. Once the transverse processes and ribs will be identified, the transducer will be moved slightly caudal into the intercostal space between adjacent ribs to identify the thoracic paravertebral space. The space appears as a wedge-shaped layer demarcated by the hyperechoic reflections of the pleura below and the internal intercostal membrane above. The thoracic paravertebral space will be identified at this point.

             At the puncture site, infiltration will be done subcutaneously with 3-4 ml 2% lignocaine using a 22G needle. The block needle will be inserted below the probe in an in-plane approach under ultrasound guidance to reach the paravertebral space under vision and the needle will be advanced perpendicular to the skin in all planes until the transverse process is contacted. Once the transverse process is located, the needle is withdrawn to the subcutaneous tissue and readvanced in a cephalad direction to pass through the space between the two transverse processes until loss of resistance(LOR) will be elicited as the needle traverses the SCTL, usually within 1.5 to 2cm from transverse process. The LOR felt as the needle enters the TPVS, is subjective and indefinite. After aspiration of the syringe, 15 ml of 0.375% Ropivacaine without any adjuvant will be injected in TPVS  under ultrasound guidance which will result in anterior displacement of pleura.

GROUP 2: USG-CTFB

             In CTFB intervention, the T4-T5 thoracic spinal level will be identified using high frequency linear transducer (5-12 MHz) oriented in a parasagittal plane counting down from the first thoracic vertebra to the first rib junction. The positions of the fourth and fifth ribs will be identified and marked with the transducer orientated longitudinally. The transducer will be  guided in a lateral to medial direction while maintaining a parasagittal orientation and observing for the transition from ribs to the TP. The transducer will be  moved medially to identify the base of the TP, a slight step-down from the hyperechoic shape of the TP. The pleural structure can be  determined in this view by gradually moving deeper and away from the TP.

            The injection procedure will be  performed using an inplane technique under real-time ultrasound guidance. An 23-gauge block needle will be directed caudad-to-cephalad until the needle tip contacted the anteroinferior part of the base of the T4 TP. The correct needle tip position was confirmed by the injection of 1.5 to 2 mL of 0.9% normal saline solution to visualize the spreading from posterior to anterior following which 15 ml of 0.375% ropivacaine will be injected over 1-2 minutes under real time ultrasound guidance.

     Induction. of anaesthesia will be achieved with Intravenous (IV) morphine 100 mcg/kg followed by IV Propofol 2mg/kg. Intubation of the trachea will be facilitated by Atracurium (0.5mg/kg). The airway will be secured by appropriate size Endotracheal Tube (ETT), and the position of ETT will be confirmed clinically by 5-point auscultation and with capnography. Anaesthesia will be maintained with oxygen and isoflurane with a target MAC of 0.8-1.2. Boluses of Atracurium will be administered accordingly to maintain muscle relaxation. If tachycardia occurs > 20% of baseline, or mean arterial pressure increases by > 20% of baseline, 25mcg/kg bolus of morphine is given. IV Acetaminophen 1g will be given as intraoperative analgesia.

Injection Ondansetron 4 mg will be administered approximately 10 minutes before skin closure  & residual of neuromuscular (NM) blockade will be reversed by Inj. Neostigmine 50µg/kg IV and Inj. Glycopyrrolate 10µg/kg IV. Tracheal extubation will be done after confirmation of adequate neuromuscular recovery. The patient will be shifted to PACU, wherein the NRS scores will be noted at 2 hours, 4hours, 6 hours, 12 hours, 24 hours at rest, on coughing, and change of posture.  A change on the NRS of 20% between two time-points of an assessment is regarded as being clinically significant.

Postoperative analgesia will be provided with Morphine IV by a Patient Controlled Analgesia (PCA) pump (in the first 24 hours), which will be set to deliver a bolus of 1mg with a lockout interval of 10 minutes and a 10mg 4 hours limit. The time to the first bolus dose will be recorded as the first analgesic requirement during the first 24 hours.

Paracetamol 1g IV is given eighth hourly to all patients in both groups for 24 hours. Total opioid consumption during the 24 hours postoperative period will be recorded at 2 hours, 4hours, 6 hours, 12 hours and 24 hours.

Patient will be observed for any adverse events, example: PONV, respiratory depression and pruritus.

The number of episodes of PONV will also be noted for the first 24 hours. The PONV scoring will be done at 2 hours, 4hours, 6 hours, 12 hours, and 24 hours.

·       0 = no nausea or vomiting

·       1 = nausea but no vomiting

·       2 = vomiting once in 30 minutes

·       3 = two or more episodes of vomiting in 30 minutes

If the patient has nausea or vomiting, IV Ondansetron 4-6mg will be administered. In case of inadequate relief, IV metoclopramide 10 mg will be administered.

Routine hemodynamic monitoring and SpO₂ and respiratory rate will be done in the first 24 hours to maintain Spo2 of >94% with O2 supplementation if needed by the patient and respiratory rate >10/minute. The patient will be said to be having respiratory depression if any one of the following variables [respiratory frequency <8/min, SpO₂ < 90% (with supplementary oxygen by facemask at 5litres/min] are present. If the patients experience pruritus, IV naloxone 0.25-1 mcg/kg will be administered for its management.

Patient satisfaction with the technique will be assessed 24 hours after the operation on an 11-point patient satisfaction score (0-unsatisfied, 10-most satisfied).