The aim of the study is to compare the effectiveness of ultrasound guided pectoral nerve block versus mid-point transverse process block for postoperative analgesia in patients undergoing modified radical mastectomy

preoperative assessment will be done for every patient including history, clinical examination &laboratory investigation ( coagulation profile ) according to age , physical state . all patients will be instructed about numeric rating scale of pain (NRS) , intravenous access will be placed under complete aseptic condition . on arriving to operating room , standard ASA monitoring ( ECG , non invasive arterial blood pressure and pulse oximetry ) will be assembled. baseline readings of all vital data will be recorded before induction , induction of anesthesia will be done by propofol 2mg/kg , atracurium 0.5mg/kg and fentanyl 1mcg/kg . endotracheal intubation will be placed then patients will be mechanically ventilated with setting keeping end tidal CO2 between 35-45 mmHg . anesthesia will be maintained with volatile anesthetic (isoflurane) and atracurium 0.1mg/kg every 20 minutes, maintenance fluid will be given according to patient's weight , fasting hours , and duration of surgery . incremental doses of fentanyl ( 1mcg/kg ) will be given every 2 hours according to duration of surgery . all patients will receive 1gm parecetamol with skin closure .

both blocks will be done by an experienced anesthesiologist in sonar guided peripheral nerve blockade under complete aseptic conditions, after induction of general anesthesia .

patients will be randomly divided into two groups P-Group : pectoral nerve block patient will be positioned in supine position and patient's arm next to the body , the linear probe (10-12 MHz) will be positioned in the parasagittal plane below the lateral half of the clavicle . the pectoral branch of the thoraco-acromial artery will be identified between pectoralis major and minor using color doppler. in-plane needle approach will be used , and the needle will be advanced from medial to lateral direction enter the plane between pectoralis major and pectoralis minor , a volume of 10ml of bupivacaine 0.5% will be injected between the two muscles (the interpectoral plane ) with careful intermitted aspiration to avoid intravascular injection . Then the needle will be advanced into the plane between te pectoralis minor and serratus muscles , and 10ml of bupivacaine will be injected watching for the spread between two muscles under ultrasound guidance with careful intermitted aspiration to avoid intravascular injection M-Group : mid-point transverse process block in the lateral position , the T4 spine will be counted by ultrasound and high frequency linear probe (10-12MHz) will be placed longitudinally , approximately 2.5 cm lateral to the midline the needle will be advanced in plane from cranial to caudal direction , the desired end point for the needle tip will be the midpoint of the line between the posterior border of transverse process of T4 and the pleura (injection will be deep to the posterior aspect of the vertebral transverse process but superficial to the superior costotransverse ligment) the needle tip does not enter the paravertebral space , a volume of titrated bolus of 20ml of bupivacaine 0.5% will be injected after aspiration to avoid intravascular injection, pleural displacement and bowing of erector spinae will be observed at the side of injection

Inclusion Criteria:

• all female patients undergoing modified radical mastectomy
• age between 35 to 65

Exclusion Criteria:

• patient refusal of procedure or participation in the study
• duration of operation more than 180 minutes
• known ASA IV or more
• local skin infection at site of the block
• contraindication of local anesthetic infiltration ( history or evidence of coagulopathy , use of anticoagulant or antiplatelet therapy , known allergy of local anethestic (bupivacaine )