A randomized comparative study for the efficacy of bilateral transversus thoracis muscle plane block versus parasternal intercostal block for perioperative opioid consumption in patients undergoing cardiac surgeries.

After obtaining approval from the institutional ethics committee and written informed consent; patients scheduled for valvular cardiac surgery under general anesthesia satisfying inclusion criteria will be enrolled in the study.

At the time of pre op visit, patients will be familiarized with a 10 cm visual analogue scale for pain assessment. Patient will be given Tab Alprex 0.5 mg previous night. NBM status, PAC and consent will be checked in the operating room. Routine vital monitors will be attached for ECG, SpO2, EtCO2, entropy. Peripheral IV line, IJV central line, arterial line for invasive BP monitoring will be secured under local anesthesia and baseline vitals will be noted before induction. After randomization, patient (n=60) will be allocated into specific group as per study protocol by sealed envelope method.

Patient will be induced with Inj. Midazolam 0.05 mg per kg, Inj. Fentanyl 4 micrograms per kg, Inj. Etomidate 0.3 mg per kg, Inj. Rocuronium 0.9 mg per kg to facilitate endotracheal intubation . Patient will be mechanically ventilated by 100 percent O2 with tidal volume 6 to 8 ml per kg for 3 minutes and under direct laryngoscopy patient will be intubated with appropriate size ETT. Bilateral air entry will be checked and tube will be fixed. EtCO2 35 to 45 mm Hg will be maintained by adjusting respiratory rate of 12 to 16 breaths per minute.

In Group A, Bilateral transversus thoracis muscle plane block, patients will receive bilateral USG guided block immediately after induction and intubation. The block will be executed with aseptic technique. The block will be given at T4 to T5 intercostal space bilaterally with a 22 G atraumatic spinal needle using 40 ml 0.5 percent Ropivacaine with adjuvant Fentanyl 25 micrograms  (20 ml each side) before incision and local infiltration of 10 ml 0.5 percent Ropivacaine on surgical drainage sites at the end of the surgery.

In Group B, Parasternal block, patients will receive bilateral USG guided block immediately after induction and intubation with aseptic technique. The block will be given between pectoral major and intercostal muscles, proximal to the sternum from 2nd to 6th intercostal space with 40 ml 0.5 percent Ropivacaine with adjuvant Fentanyl 25 micrograms (4 ml in each space from 2nd to 6th intercostal space on each side) before incision and local infiltration with 10 ml 0.5 percent Ropivacaine at surgical drainage sites at the end of the surgery.

In both the groups, patients will be shifted to ICU with ETT in situ at the end of the surgery.

In both the groups IV Fentanyl ( 25 micrograms per ml) at a basal infusion rate of 1 ml per hour and a bolus of 1 ml given by the patient him/herself whenever needed with a lockout interval of 15 minutes for 48 hours after extubation. If the patient will still experience pain ( VAS more than equal to 4), then Inj. Tramadol 50 mg will be given.

Fentanyl requirement, VAS score and hemodynamic parameters will be assessed immediately, 2, 4, 6, 12, 18, 24, 30, 36. 42 and 48 hours post extubation. Side effects or complications if any will be noted. End point of the study will be 48 hours after extubation.