The incidence of breast cancer as well as the need for surgical treatment has increased.

Breast cancer surgery (BCS) is associated with many complications such as increased incidence of acute and chronic postoperative pain, postoperative nausea and vomiting (PONV), delayed hospital discharge.

Acute postoperative pain is an integral risk factor in the development of chronic pain after BCS.

Inadequate pain control can impact patient recovery including impaired pulmonary and immune function with an increased risk of ileus, thromboembolism, and myocardial infarction.

General anesthesia (GA) is the technique that commonly used for breast surgeries. The downside of GA includes inadequate pain control with high incidence of PONV . Also postoperative opioid for postoperative pain usually associated with many complications Regional anesthesia for breast surgery holds a great promise for breast cancer patients in terms of improved acute pain control with chronic pain prevention. It offers adequate analgesia while minimizing opioid consumption.

This study was designed in order to assess the efficacy and safety of PECS block as a supplement to GA in modified radical mastectomy (MRM) . Also to assess its role in decreasing the amount of opioid in the intra- and postoperative period after MRM. Also to assess its role in decreasing postoperative complications after BCS such as postoperative nausea and vomiting, delayed hospital discharge,and acute postoperative pain. Also to assess the role of dexmedetomidine in prolongation of the analgesic effect of PECS block.

Breast cancer is the most frequent cancer among women; it causes the highest number of cancer-related deaths among them globally. The prognosis has improved considerably over the past 30 years, and the 5-year survival rate of patients has been increased due to the advances in the early detection and treatment of breast cancer.

Breast cancer surgery is associated with many complications such as increased incidence of acute and chronic postoperative pain, postoperative nausea and vomiting, delayed hospital discharge, and cancer recurrence. One of the most important complications is the occurrence of acute postoperative pain. Acute postoperative pain is an integral risk factor in the development of chronic pain after breast cancer surgery (BCS).

Inadequate pain control can impact patient recovery including impaired pulmonary and immune function with an increased risk of ileus, thromboembolism, and myocardial infarction. These factors can further increase the hospital length of stay, increase the healthcare costs, and decrease the patient satisfaction.

General anesthesia, including intravenous and inhalational agents, is the technique that commonly used for breast surgeries. The drawbacks of general anesthesia include inadequate pain control with high incidence of nausea and vomiting. Also the use of opioid and non-opioid analgesics for postoperative pain usually associated with many complications.

Regional anesthesia for breast surgery holds a great promise for breast cancer patients in terms of improved acute pain control with chronic pain prevention. It offers adequate analgesia while minimizing opioid consumption and its related side effects.

Several techniques of blocks for breast surgery have been described. Thoracic epidural and paravertebral blocks were the gold standard techniques to achieve this goal. However, these techniques are generally performed before general anesthesia, and not all anesthesiologists feel comfortable using such invasive procedures in BCS. AS an alternative for these techniques, pectoral nerves (PECS) block has been reported as a promising technique during BCS.

PECS block is an interfascial peripheral nerve block described since 2011.The original block is PECS I block, in which local anesthetic is deposited between the pectoralis major and pectoralis minor muscles to block the lateral pectoral nerve (C5, 6, 7) and medial pectoral nerve (C8, T1) providing analgesia to the anterior chest wall.

PECS II block is a modified PECS I. In this block, local anesthetic is injected between the serratus anterior and pectoralis minor muscle at the third rib in addition to the original block aimed to block thoracic intercostal nerves (T2-6) including intercostobrachial nerve and long thoracic nerve (C5-C7). This modification aimed to extend analgesia to the axilla; this is needed for axillary clearance, necessary for wide excisions, tumorectomy, lymph node excision and several types of mastectomies.

It differs from thoracic epidural and paravertebral blocks as there is no associated sympathetic block. It can be performed while the patient in the supine position and it can be done before or after induction of general anesthesia.

The use of ultrasound (US) makes the pectoral nerve block more accurate and less injurious to nearby structures such as the parietal pleura. It helps direct visualization of anatomical structures, it finds the possible variations in the origin, course, the accompanying structures of the medial and lateral pectoral nerves and their relation to the important structures such thoracoacromial artery and parietal pleura to avoid their injury during performing the PECS block.

The addition of dexmedetomidine to bupivacaine can improve the quality of the block, significantly prolong the duration of analgesia, and provides better pain control postoperatively without major side effects.

Inclusion Criteria:

Hospitalized for modified radical mastectomy. American Society of Anesthesiologists (ASA), physical status II. Age between 21-65 year.

Exclusion Criteria:

Patient's refusal. Preexisting coagulopathy or anti-coagulant therapy. Local infection at site of injection. Pregnancy or breast feeding. Body Mass Index (BMI) > 35kg/m². Allergy to local anesthetics and drugs used. Prior breast surgery except for diagnostic biopsies.