The shoulder, being an anatomical region innervated by different nerves, has a wide variety of analgesic approaches, which differ depending on the practitioner. New approaches are being developed based on the different innervation channels demonstrated in clinical and cadaver studies. Over time, the effectiveness of axillary block, suprascapular block, interscalene block, local infiltration, and various combinations, as well as non-regional methods, has been observed. The goal of these approaches is to achieve the highest possible level of patient comfort, high analgesic efficacy, and minimal complications. Studies have shown that the interscalene block has the highest analgesic efficacy and the most ideal postoperative results; therefore, it is frequently used as the gold standard in this field. Providing effective analgesia with a single intervention can also be cited as an aspect that increases patient comfort and simplifies the procedure. In interscalene block; unilateral transient diaphragmatic paralysis due to the spread of local anesthetics to the C7 nerve root, respiratory problems and potential spinal/epidural complications, new approaches are being followed and researched. Results from cervical/high thoracic erector spinae plane block (ESPB) and infraspinatus-teres minor interfascial plane block (ITMIPB) studies, which are the subject of new studies, strengthen the hypothesis that they provide effective analgesia. Neither of these blocks, performed with ultrasonography, carries the risks present in interscalene block. Although the usual risks of a peripheral nerve block are present for these procedures; the block sites are considered safer due to its distance from vascular structures and the reduced risk of additional complications. While small sample studies exist for each type of block, no studies comparing their effectiveness have been found. Besides reduced complications, another advantage of these two blocks is their ability to provide effective analgesia with a single-point injection. The aim of this study is to compare the analgesic efficacy of Cervical Erector Spine Plane Block (ESP) and Infraspinatus-Teres Minor Interfascial Plane Block (ITMIPB) applied for postoperative analgesia in ASA I-III patients undergoing shoulder surgery.

Inclusion Criteria:

• Adults scheduled for elective shoulder arthroscopy
• ASA I-II-III patients
• Patients age between 18-80

Exclusion Criteria:

• Patients with previously known allergy to local anesthetics.
• Patients with insufficient pulmonary functions (Severe obstruction or restriction in Pulmonary Function Test)
• Patients with ASA IV or higher
• Patients who suffered from any complications related to anesthesia or surgery
• Patients with additional body part injury
• Pregnant or breastfeeding women

Beginning 6 months following publication and ending 5 years after publication.

Individual participant data will be available to qualified researchers upon reasonable request to the principal investigator. Requests will be evaluated based on scientific merit and ethical considerations.

Our study is a single-blind study. Outcome Assessor will be masked to performed block type.