Efficacy Of Bilateral Parasternal Sub Pectoral Catheters (Sternal Block) For postoperative Analgesia FollowingSternotomy-A Randomized Double Blinded Cross Over Clinical Trial

In the postoperative period, Pain relief reduces endocrine and neurohumoral responses, pulmonary complications and prolonged hospitalization. Thus effective postoperative analgesia enhances postoperative recovery and reduces morbidity.  we designed this cross over study to find out the efficacy of bilateral parasternal sub pectoral catheter (sternal block) on dynamic analgesia in post cardiac surgical patients. Sample size was calculated using “sample size calculator for clinical research app†(version 2.0 developed by Manon Girard) using cumulative rescue analgesic (morphine) requirement for first 48 hours. Vedat eljezi et al had found in his study on Saline versus Ropivacaine infusion through sternal block catheter that median (IQR)cumulative morphine requirement in the first postoperative 48 hours was 30 mg(25-39 mg) in saline group. To demonstrate 35% reduction in the cumulative morphine requirement (15 mg) with SD (9.3) calculated by (IQR/1.5) with the power of 90% and a error of 0.05, We calculated sample size of 24 (12 per group). To meetout dropouts we are planning to recruit 15 per group. All patients will be allocated to one of the study groups by block randomization with block size of 6 using “Randomizer for clinical trial Lite†app.  Developed by MEDSHARING. Once surgical procedure over, 30 patients satisfying inclusion and exclusion criteria will be recruited for this study. After covering the surgical wound with betadine soaked gauze, Chest from supra sternal notch to xiphisternum and laterally up to midclavicular line will be cleaned with antiseptic solution and draped. A Sonosite X-Porte (Sonosite, Bothell, Washington) ultrasound system with multi-beam (compound imaging) capability and with a high- frequency linear array transducer (HFL50, 15-6 MHz), will be used for the ultrasound guidance. The ultrasound probe will be draped with sterile cling drape up to 10 cm below the foot print after applying jelly on it for acoustic coupling. Liberal amount Betadine solution will be used for acoustic coupling between skin and the draped probe. The transducer probe will be placed parallel to sternum near the costosternal junction and moved down wards to identify the caudal end of pectoralis major muscle and the cranial end of rectus muscle. Two intercostal spaces above the caudal end of pectoralis major muscle will be identified. At this place, 18 G Tuohy needle will be inserted from cephalic end using in-plane technique and the plane between the pectoralis major muscle and the external intercostal membrane will be identified after hydro dissection with normal saline. 20 G epidural catheter will be placed in the plane through the needle and 2-3 cm of catheter will be inserted in the plane under ultrasonic visualization. After placing the catheter bilaterally, they will be secured with suture and dressing of the wound and catheter site will be done. Then patients will be shifted to CTVS ICU for overnight elective post operative ventilation. Sedation, titration of vasopressors and ventilatory settings will be managed according to discretion of anaesthesiologist. On POD 1, at 6am will be taken as Time 0. 10 ml of study drug will be injected as a bolus every 6th hourly from Time 0 till 48 hours by clock irrespective of patient pain status. After the first dose, Patients will be put on CPAP mode and will be extubated after an hour according to the unit protocol. All patients irrespective of group allocation will receive one dose of IV paracetamol 1 gm 30 minutes s before extubation and 650 mg Tab.Paracetamol every 6th hourly then onwards for the next 3 days. As per the pain management education the preoperative, patients will be instructed to demand analgesia whenever they feel pain more than 5 on the NRS scale .1st Rescue analgesic NSAID ,Inj.Ketorolac 30 mg IV over 10 minutes will be given and the pain score will be reassessed after 20 mins. If the pain score on NRS scale still more than 5, the 2nd recue analgesic, potent narcotic, Inj. Morphine 3mg IV bolus will be given and the pain score will be reassessed after 15 minutes. Maximum limit of NSAIDS is 90 mg/24hrs (3 doses with minimum interval of 4 hours between doses 0). Similarly Inj. Morphine can be repeated to a maximum of 9mg (3doses) at 15 minutes interval. Beyond that the anaesthetic consultant will be informed to care of the further course of action depending on clinical condition. Anaesthesia resident who is blinded to group allocation will visit the patient at the following specified intervals: 9am, 1pm, 6pm and 10 pm on POD 1 and 2 and record study parameters. Efficiency of pain relief will be assessed using Static and dynamic NRS score. Functional outcome of the pain relief will be assessed using quality of cough on 3 point scale, Peak Expiratory flow rate on L/minute and incentive spirometry on ability to lift balls. Cumulative rescue analgesic (morphine and Ketorolac) consumption at the end of 24 and 48 hours from Time 0 will be noted. Complications like sedation using ramsay sedation score, local anaesthetic systemic toxicity, post operative wound infection will be recorded. Patient satisfaction score about pain relief on four-point scale (1 highly satisfied, 2-satisfied, 3-unsatisfied, 4-highly unsatisfied) will be assessed at the end of 24 and 48 hours from Time 0 will be recorded.