Effectiveness of Shoulder block versus Interscalene block for Postoperative analgesia in Arthroscopic Shoulder surgeries, A Randomised Controlled trial

After the institutional ethics committee approval, this prospective randomised controlled trial will be conducted in 74 American Society of Anesthesiologists (ASA) grades 1 and 2, adult (18–60 years) patients of either sex, undergoing elective unilateral arthroscopic shoulder surgery under general anaesthesia.

All patients will undergo a detailed pre-anaesthetic(PAC) check-up and will be fasting after midnight, a written informed consent will be taken for the procedure .An intravenous (IV) access will be secured using 18-G  IVcannula on the opposite hand and Ringer lactate solution will be started.Standard monitors will be attached in the form of five-lead ECG, noninvasive blood pressure monitor, pulse oximeter, and capnograph. The patients will be instructed before hand about how to use visual analogue scale (VAS) for pain postoperatively. The Interscalene block( ISB) and Shoulder block( ShB) will be performed 30 min before induction of General Anesthesia under ultrasound guidance

The procedural duration of the blocks is defined as the time that block needle will beunder the skin. The procedure will be performed by experienced who has performed at least 100 blocks.Preoperative measurements (baseline vital parameters, procedural duration, pain on injection, sensory and motor block) will be noted by this person and handed over to the investigators. The patients will be randomly allocated into 2 groups of 37 each using block randomisation technique and investigator assessing the  postoperative outcomes will be blinded to the group allocation and to the procedure and  allocation concealment will be achieved using opaque sealed envelope technique

All patient will be tested for local anesthesia skin test before the start of the procedure.Group ShB(shoulder block group,n = 37) will be given 20 ml of 0.375% Ropivacaine with 8mg Dexamethasone  that is 10ml  each for SSN (suprascapular nerve)and AN(axillary nerve) block and Group ISB(interscalene block group,n = 37) will be given 20 ml 0.375% Ropivacaine with 8mg Dexamethasone.

For performing Interscalene block, the patients will be positioned supine with neck slightly extended and the head turned away from the side to be blocked. The skin of the neck will be sterilized and the ultrasound probe will be placed at the level of the cricoid cartilage over the Sternomastoid muscle and moved laterally to identify the carotid artery, jugular vein and then laterally and posteriorly until visualization of the Brachial plexus as hypoechoic nerve structure between the anterior and middle scalene muscle. Confirmation of absence of vascular structure will be made by colour Doppler. After skin infltration with 2 ml of lidocaine 2% a 22-G will be insertedin plane with the probe to visualize the entire needle length. When the needle tip will be seen close to the Brachial plexus roots, an assistant will start to inject the local anesthetic (20 ml 0.375% Ropivacaine with 8mg dexamethasone) with aspiration every 5 ml to avoid intravascular injection and the local anesthetic spread will beobserved.

Block success will be assessed every 5 min from the end of local anesthetic injection until readiness for surgery. Sensory block will be assessed over C5–C7 dermatomesand by pinprick using 22-G needles over the lateral side of the forearm and thumb(C5 – skin over deltoid, C6 – thumb tip, C7 – middle fingertip) this will be assessed on 3 point scale (0 = no block/ normal sensation; 1 = partial; a touch of pinprick but no pain; and 2 = complete; absence of sensation to pinprick) . Motor block will beassessed by restriction of shoulder abduction and elbow flexion based on 3 point scale (0 = no block; normal movements of the shoulder, arm, and forearm, 1 = partial block; inability to perform movements against resistance and 2 = complete loss of motor power)The block will be considered a failure if the block will be not successful 30 min after injection of the local anesthetic.

Suprascapular nerve block will be performed with the patient sitting and his arm flexed at the elbow and resting on his anterior thigh. After skin sterilization, a linear ultrasound probe is placed in a sagittal plane at the superior medial border of the scapula. The probe is moved laterally and then placed parallel to the scapular spine. It is then tilted cephaled to identify the scapular fossa where the supraspinatus muscle and the bony fossa under it can be visualized. Then by moving the transducer slowly laterally, the suprascapular notch can be identifiedwhere the suprascapular nerve can be seen as a round hypoechoic structure about 4cm in depth behind the transverse scapular ligament. 2ml of 2% lidocaine will beused to anesthetize the skin, and then a 22-G  nerve block needle  will be inserted in plane with the ultrasound probe. When the needle tip will be seen in the suprascapular notch and after confirmation of absence of vascular structure by colorDoppler,10 ml of 0.375% Ropivacaine will be injected with aspiration every 3 ml to avoid intravascular injection and the spread of the local anesthetic will be observed.

Axillary nerve block, this will be performed while the patient will be still in the sitting position with the shoulder adducted and internal rotation at 45°, the elbow flexed at 90°and the hand resting on the knee. The probe will be placed parallel to the shaft of the humerus about 2 cm below the posterolateral part of the acromion on the dorsal side of the arm. The surgical neck of the humerus will be identified then a short-axis view of the circumflex artery (which is the most reliable land mark) will be visualized. The axillary nerve is located just cranial to the circumflex artery in the neurovascular space between the teres minor muscle superiorly, the deltoid muscle posteriorly, the triceps muscle caudally, and the shaft of the humerus anteriorly. A 22-G needle will be inserted in line with the ultrasound probe from its cranial end to place the needle tip just cranial to the circumflex artery under the muscle fascia. Then remaining10ml of 0.375% ropivacaine will be injected slowly while aspirating every 3ml to avoid intravascular injection.

Success of sensory block in shoulder block will be assessed after 30 min, on a 3-point scale. The sensory block will be assessed over lateral aspect shoulder (regimental badge area, supplied by the AN) and Motor block by restriction of shoulder abduction and external rotation . Patients with complete block failure at 30 min will be excluded. Immediate complications, such as paraesthesia, Horner’s syndrome, respiratory distress etc. will be assessed.

After the blockade, all patients will receive General anesthesia using premedicationsMidazolam and  glycopyrrolate and will be induced with inj propofol 2.0 mg/kg, fentanyl 2 Î¼g/kg, and cisatracurium 0.2 mg/kg after adequate relaxation  insertion of endotracheal tube insertion will be done, and controlled ventilation is started. Anesthesia will be maintained with Air and oxygen at a ratio of 1:1 and , isoflurane 1%, and 0.03 mg/kg cisatracurium. Additional analgesia inj fentanyl (2 µg/kg)will be given intraoperatively if hemodynamic parameters are exceeding 20% of the baseline value. At the end of surgery, anesthesia will be stopped and neuromuscular blockade will be reversed with 0.05 mg/kg neostigmine and 0.01 mg/kg glycopyrrolate.

Postoperative analgesia will be assessed using VAS(Visual analogue scale) scoring that is  0=no pain to 10=worst pain at 0,3,5,10,15,24 hours . Rescue analgesia in the form of Inj. paracetamol 1 g IV will be administered on demand or if VAS will be ≥ 4 (maximum 4 doses, 6 h apart). Inj. tramadol 50 mg will be administered to patients having inadequate pain relief after  paracetamol infusion as secondary rescue analgesic. Time of first rescue analgesia (the time from operating room discharge until the first dose of rescue analgesia) and total analgesia required (number of times analgesic rescue doses) will be noted. Satisfaction in terms of overall quality of pain relief will be rated by the patient at the end of 24 h as excellent, good, fair, and poor.

The categorical data will be expressed as numbers (percentages) while continuous data will be presented as mean ± standard deviation (SD) and median values. The data normality will be checked by using the Kolmogorov–Smirnov test. The comparison of the variables, which will be quantitative and normally distributed, will be analysed using unpaired t-test Comparison of VAS score between 2 groups will be done by  Mann Whitney. The comparison of qualitative variables  will be  analysed using Chi-square test/Fisher’s exact test. The statistically significant difference is considered as a P value <0.05. Sample size was estimated on the basis of previous study Suman Saini et al in which Mean difference of two groups and taking 80% study power and an type 1 error of 0.05.To allow for study error and attrition, 37 patients were included in each group