The goal of this clinical trial is to compare Ultrasound Guided Erector Spinae and Ultrasound Guided Serratus Anterior Plane Block post Modified Radical Mastectomy in adult females. the main questions it aims to answer are:

• Which of the two blocks has a better analgesic effect?
• Which of the two blocks is safer as regards inducing a pneumothorax and affecting the hemodynamics?

Participants:

• Will be divided into two groups after signing the informed consent.
• After being anesthetized and before surgical incision; the blocks will be given to the patient.
• Lung Ultrasound will be done for each patient to rule out pnemothorax once before the surgery and another after the end of surgery while the patient is being anesthetized.
• Patients that will experience pneuomothorax will be excluded from the study, and will be treated according to its size.
• Follow up of the patient for 24 hours postoperative to record the VAS score continuously, with giving increments of pethidine intravenously to relief pain.

Breast surgeries belong to the most frequently performed procedures and are often associated with a high intensity of pain in the postoperative period.

Regional anesthesia techniques, have been the gold standard of postoperative pain management for breast surgeries. In recent years, the development of new techniques of regional anesthesia, which is due to the extensive implementation of ultrasound imaging, has enabled the use of a number of new blockades.The core mechanism of action in fascial blocks consists of blocking the nerve structures that supply a certain area of the trunk after deposition of local anesthetic within the fascial and fasciomuscular compartments. According to the current state of knowledge, the available options include Erector spinae plane block (ESPB) and Serratus anterior plane block (SAPB), however their recommendation in breast surgery requires more extensive scientific evidence.

Serratus anterior plane block acts on lateral branches of the intercostals nerves, blocking pain reception in the chest wall, while Erector spinae plane block involves the deposition of local anesthetic in the interfascial plane between erector spinae muscle and tips of the transverse processes of the vertebrae.

There is a scarcity of literature comparing ESPB and SAPB in patients undergoing breast surgeries.

Proponents of these techniques champion their ability to provide efficacious analgesia and anesthesia whereas critics cite a reportedly high failure rate and complications such as pneumothorax.

The German S3-guidelines suggest Lung Ultrasound as a possible alternative to Chest X-ray for the diagnosis of post-interventional pneumothorax.

Dexamedetomidine is a highly selective drug α2-adrenergic receptor agonist. Dexmedetomidine has the characteristics of sedation, analgesia, anti-anxiety, inhibition of sympathetic activity, mild respiratory inhibition, and stable hemodynamics. Numerous studies has revealed that dexmedetomidine in peripheral nerve blocks can shorten the onset time of anesthesia and prolong the time of sensory and motor nerve blocks.

Inclusion Criteria:

• ASA Physical Status II, or III.
• Age 21 - 65 years.
• Female gender

Exclusion Criteria:

• ASA IV, V, VI.
• Infection at site of block.
• Coagulopathy, or patients on antiplatelets, or anticoagulants.
• Previous anesthetic allergy to bupivacaine.
• Distant organ metastasis.
• Male gender.