Evaluation of Multimodal Analgesia With NOL

In the elective laparoscopic cholecystectomy procedures to be performed in the general surgery operating room for 80 patients, 80 envelopes containing written papers indicating the Multimodal Analgesia group (Group M) and the control group (Group K) will be prepared. On the morning of the operation, an envelope will be randomly drawn by operating room personnel in a blinded manner to determine the patient's inclusion group. The patients will be randomized into two groups: the Multimodal Analgesia group (Group M), receiving Erector Oliq Interfascial Plane (EOIP) block, NSAID, and magnesium infusion, and the control group (Group K).

Patients will be informed about the procedures to be performed before the surgery, and written consent will be obtained. After patients are taken to the operating table, standard ASA monitoring (electrocardiogram, non-invasive blood pressure, O2 saturation, body temperature) along with NOL (Nociception Level) and BIS (Bispectral Index) monitoring will be applied. A peripheral venous line will be established on the dorsum of the hand for normal saline infusion. All blocks will be performed under ultrasound guidance.

In Group M, after routine anesthesia induction, intravenous magnesium loading of 30 mg/kg will be followed by an infusion of 10 mg/kg/hour. Subsequently, in the supine position, after the necessary field preparation and ultrasound (USG) setup, a linear ultrasound probe will be positioned sagittally between the mid-clavicular and anterior axillary lines at the level of the 6th rib, with the orientation marker pointing cranially. Identification of the 6th rib can be achieved in two ways: either by placing the ultrasound probe at the level of the lower costal margin where the 10th rib is located and then counting upwards, or by identifying the 7th rib at the level of the xiphoid process and then moving the ultrasound probe one rib upward.

The ultrasound probe will then be rotated to obtain a paramedian sagittal oblique view, with the cranial end slightly medial and the caudal end lateral, approximately 1 to 2 cm medial to the anterior axillary line. Sequentially, from superficial to deep, the following structures will be identified: skin, subcutaneous tissue, external oblique muscle, intercostal muscles between the ribs, pleura, and lung.

For the injection, the skin entry point will be at the medial edge of the anterior axillary line, just cranial to the 6th rib level, using a peripherally directed block needle (Echoplex+, VygonTM, France) advanced in a superomedial to inferolateral plane along the external oblique muscle. The tip of the peripherally directed block needle will be adjusted to the tissue plane between the external oblique and intercostal muscles at the caudal end of the 6th rib and 6th-7th intercostal space. A sterile preparation of 20 mL 0.25% Bupivacaine will be injected into the tissue plane between the 6th and 7th ribs using the hydrodissection technique, and then the peripherally directed block needle will be directed caudally towards the eighth rib.