Interscalene Block Versus Upper Trunk Block in Shoulder Arthroscopy: Randomized Comparative Study of the Ease Between the Two Techniques Among Residents

Investigators hypothesize that upper trunk block (UTB) is not inferior to interscalene brachial plexus block (ISB) regarding analgesia, easier to perform, with superior success rates, and less side effects in shoulder arthroscopy surgeries when undertaken by anaesthesia trainee.

A sample of 120 patients {60 patients in ISB group and 60 patients in UTB group} is needed to detect difference in 20% in rate of success of block also this sample is sufficient to detect difference in {Duration of the block performance, visualization of the anatomic structures and Consultant guidance, with a power 80% at a significance level of 05. Sample size was calculated using Number Cruncher Statistical Systems (NCSS) 2004 and Process Automation Software System (PASS) 2000 program Patients will be excluded if they have severe pulmonary disease, allergy to any of the study medications, local infection at any of the puncture sites, chronic gabapentin or pregabalin use, chronic opioid use, preexisting neuropathy of the operative limb, herniated cervical disc, or body mass index more than 35 kg/m2.

Upon arrival to the block room, the procedure will be explained to patients and a written informed consent will be obtained. Patients will be randomly categorized into two equal groups (group ISB and group UTB) using a numbered sealed envelope method. All blocks will be performed guided by a 5-13 MHz linear ultrasound (US) probe of a Sonosite (M-Turbo; Sonosite Inc, Bothell, W, USA) portable US machine.

Baseline diaphragmatic assessment will be performed before the nerve block in the sitting position. A curved array 3-5 MHz transducer of a Sonosite (M-Turbo; Sonosite Inc, Bothell, W, USA) portable US machine will be placed inferior to the costal margin in a longitudinal orientation at the anterior axillary line on the left or in the midclavicular line on the right. The ultrasound beam will be directed medially and cephalad to visualize the posterior third of the hemi-diaphragm by using either the spleen or the liver as an acoustic window, relatively. First the view will be obtained in a two-dimensional B-mode then the M-mode sonography will be used to quantify the extent of diaphragmatic excursion between full inspiration and full expiration once a view of the curved, hyperechoic diaphragmatic line has been obtained. This assessment will be carried out by the research anaesthetist.

Blocks will be carried out by anaesthesia residents who have one year experience in ultrasound guided regional anesthesia under direct supervision of a consultant anaesthetist (After demonstrating five successive blocks in each technique). Patients, surgeons, and the research anaesthetist will be blinded to the block technique.