Postoperative pain is an important issue in patients underwent mastectomy and axillary dissection surgery. Postoperative effective pain treatment provides early mobilization and shorter hospital stay. The US-guided erector spina plane block (ESPB) may be used for postoperative pain treatment following breast surgery. It is a novel interfascial block that was defined by Forero. Rhomboid intercostal block (RIB) is a novel block and was first described by Elsharkawy et al. Local anesthetic solution is administrated between the rhomboid muscle and intercostal muscles over the T5-6 ribs. It has been reported that RIB may provide effective analgesia management for several breast surgeries.

The primary aim of the study is to compare postoperative pain scores (VAS), and the secondary aim is to evaluate postoperative opioid consumption, adverse effects related with opioids (allergic reaction, nausea, vomiting).

Postoperative pain is an important issue in patients underwent mastectomy and axillary dissection surgery. Postoperative effective pain treatment provides early mobilization and shorter hospital stay, thus complications due to hospitalization such as infection and thromboembolism may be reduced.

Various methods may be performed to reduce the use of systemic opioids and for effective pain treatment following mastectomy and axillary dissection surgery. Ultrasound (US)-guided interfascial plane blocks have been used increasingly due to the advantages of ultrasound in anesthesia practice. Rhomboid intercostal block (RIB) is a novel block and was first described by Elsharkawy et al. Local anesthetic solution is administrated between the rhomboid muscle and intercostal muscles over the T5-6 ribs 2-3 cm medially of the medial border of the scapula. RIB targets both the posterior rami and lateral cutaneous branches of the thoracic nerves and provides analgesia for the hemithorax from T2 to T9. It has been reported that RIB may provide effective analgesia management for several breast surgeries.

The US-guided erector spina plane block (ESPB) is defined by Forero et al. ESPB provides thoracic analgesia at T5 level and abdominal analgesia at T7-9 level. ESPB contains a local anesthetic injection into the deep fascia of erector spinae. Visualization of sonoanatomy is easy, and the spread of local anesthesic agents can be easily seen under the erector spinae muscle. Thus, analgesia occurs in several dermatomes with cephalad-caudad way. In the literature, it has been reported that ESP block provides effective analgesia after several surgeries such as open heart surgery, breast surgery, thoracoscopic and abdominal operations.

The aim of this study is to evaluate the efficacy of the US-guided ESPB and RIB for postoperative analgesia after mastectomy and axillary dissection surgery. The primary aim is to compare postoperative pain scores (VAS), and the secondary aim is to evaluate opioid consumption, adverse effects related with opioids (allergic reaction, nausea, vomiting).

Inclusion Criteria:

• American Society of Anesthesiologists (ASA) classification I-II
• Scheduled for mastectomy and axillary dissection surgery under general anesthesia

Exclusion Criteria:

• receiving anticoagulant treatment,
• known study drugs allergy,
• opioid addiction
• infection of the skin at the site of the block,
• pregnancy or lactation,

Female patients who will undergo breast surgery will be included

We will not plan to share IPD

The anesthesiologist who performs postoperative pain evaluation and the patient will not know the group.