Comparison of 0.25 percent Ropivacaine with Dexmedetomidine vs Clonidine as an adjuvant in Interscalene Brachial plexus block for post operative analgesia in shoulder arthroscopy.

Introduction

Arthroscopy is one of the greatest advancements in the field of orthopaedic surgery. The advent of such a minimal invasive procedure made away with the need for standard open surgical techniques resulting in a decrease in post op complications thereby facilitating faster recovery. Shoulder Arthroscopy, the second most performed orthopaedic procedure is now employed to treat a myriad of pathologies like labral tears, rotator cuff tears, adhesive capsulitis, subacromial impingement, degenerative arthritis, proximal biceps pathology, loose bodies etc. It also offers a comprehensive view of intraarticular pathologies if any. A study on patient perception of shoulder arthroscopy vs open techniques showed that a vast majority of patients perceived the former to be superior to open surgery in terms of functional outcome.  However, shoulder arthroscopic surgeries are reputed to produce intense post operative pain. This is usually circumvented by administering blocks like Inter scalene block which is reported to deliver excellent post-operative analgesia. It is a type of regional anaesthesia that targets the Brachial Plexus, a complex network of nerves originating from the cervical spine, and is performed with local anaesthetics, the choice of which is determined by the magnitude and duration of surgery. Long-acting drugs such as Ropivacaine or Levobupivacaine are usually employed for most surgeries.  The block can be further enhanced by using adjuvants like Adrenaline, Soda bicarbonate, Clonidine, Buprenorphine, Dexamethasone and Dexmedetomidine.

Dexmedetomidine is a highly selective a2-adrenergic agonist that inhibits Norepinephrine release, leading to enhanced analgesia and sedation. Compared to clonidine, it provides a more potent and controlled sedation, along with a faster onset of action. Clonidine, which also functions as an a2-adrenergic agonist shares a similar mechanism of action but has a more prolonged duration of action. However, its sedative and analgesic effects tend to be less pronounced than those of Dexmedetomidine.

Methodology

·       The study will be non blinded and will be conducted after obtaining approval from the Institutional Ethics Committee (IEC) and written informed consent of patients.

                            ·       42 patients of ASA grades 1 and 2 aged between 18-59 years of age undergoing shoulder arthroscopic surgeries will be included in this study and will be divided into two groups by simple randomisation in a 1:1ratio based on a computer-generated sequence - Group 1 and Group 2.

 ·       Detailed Pre- anaesthetic evaluation and relevant investigations will be done for each patient following which written informed consent will be taken.

·       The patients will be kept Nil per oral- 6 hours for solids and 2 hours for clear liquids.

·       In the operation theatre Standard monitors including electrocardiography (ECG), non-invasive blood pressure (NIBP) and pulse oximetry (SPO2) will be connected and vitals will be monitored.

·       Patients will be preoxygenated with 100% oxygen for 3 min, followed by induction with Propofol 2 mg/kg intravenously and Atracurium 0.5 mg/kg to facilitate endo tracheal intubation. Patient will be maintained on general anaesthesia with Isoflurane/O2/air mixture With a MAC value of 1.2. Muscle relaxation will be provided by intermittent boluses of Atracurium.

·       Following intubation, the patient’s head will be turned 30 degrees away from the side to be blocked and ipsilateral arm will be kept in adducted position. Supraclavicular fossa and surrounding area will be painted in circular motions and draped.

·       The block will be performed by a practitioner who has given a minimum of 20 USG guided supraclavicular blocks in the past.

·       Linear USG probe will be applied in supraclavicular fossa to visualize the brachial plexus posterolateral to the subclavian artery

·       Local infiltration at site of needle entry with 1 mL of 2% Lignocaine.

·       In both the groups, local anaesthetic drug used will be a mixture of 12ml of 0.25% Ropivacaine  .

 Group 1 (Clonidine) –  Clonidine (1mcg/kg)  + 12 ml of Inj 0.25 % Ropivacaine

Group 2 (Dexmed)- Dexmedetomidine (1mcg/kg) +12 ml of Inj 0.25 % Ropivacaine

 The primary outcome of this study is duration of analgesia which will be assessed as the time interval between extubation and the patient’s first request for pain relief:  VAS scores will be measured at 2, 4, 6, 8, 10, 12 and 24 hours postoperatively. When post op VAS score>6, Inj. Fentanyl will be given as a rescue analgesic.