Serratus Anterior Plane Block Versus Paravertebral Block for Postmastectomy Analgesia (SAM)

ًًًُُُُThe investigators are testing the efficacy of a new novel technique; serratus anterior plane block, for preventing postoperative pain after breast surgery for cancer. This block will be compared with the well-established paravertebral block.

Paravertebral block (PVB) can be considered as a well-established option to provide anesthesia and postoperative analgesia during breast surgery. For patients receiving a PVB alone or in combination with general anesthesia significant lower resting, evoked and worst pain scores compared with other analgesic treatment strategies indicating that a PVB provides improved postoperative pain control in patients undergoing breast surgery. Furthermore, there might be a reduced need for postoperative opioid requirements and consecutively a decrease in opioid-induced adverse effects in patients receiving a PVB. Anyways there are always fear of pleural injury and pneumothorax in addition to epidural and intrathecal spread of the block. A novel newly introduced field block has been described recently to block the hemithorax under ultrasound guidance that is the Serratus Anterior Muscle Plane SAM block. Still this technique to the investigators knowledge is not tried in randomized clinical studies. The aim of this study is to find out that this new technique is comparable to PVB in patients undergoing breast surgeries with or without axillary node dissection.

Serratus anterior muscle plane block with general anesthesia MARCAINE® 0.25%w/v solution for injection. DIPRIVAN® (propofol), 2 to 2.5 mg/kg NIMBEX® (cisatracurium besylate) Injection, 0.15-0.2 mg\Kg Fentanyl, 1-2 mic\Kg Paracetamol, 1000 mg\6 hours Fam® (Ketorolac), 30 mg

Paravertebral block with general anesthesia. MARCAINE® 0.25%w/v solution for injection. DIPRIVAN® (propofol), 2 to 2.5 mg/kg NIMBEX® (cisatracurium besylate) Injection, 0.15-0.2 mg\Kg Fentanyl, 1-2 mic\Kg Paracetamol, 1000 mg\6 hours Fam® (Ketorolac), 30 mg

The US probe is placed in the mid-axillary line at level of the 6th intercostal space. From caudal to cranial, an in-plane approach, the block needle is inserted until the tip is placed between SAM and intercostal muscles and the LA injection will be visualized in real-time. The injection usually consists of 0.4ml/kg of bupivacaine 0.25% plus adrenaline (5ug/ml). Intraoperatively, all subjects will receive a general anesthetic using inhaled anesthetic and oxygen. Intravenous fentanyl will be administered for cardiovascular stability to noxious stimuli.For postoperative analgesia, all subjects will receive oral acetaminophen. Patients will receive a ketorolac IV injection then morphine as a rescue analgesic for breakthrough pain.

After skin preparation and sterile draping applied. Target paravertebral space will be located using US guidance. The paravertebral space between the third and fourth thoracic vertebrae will be identified in a parasagittal view approximately 3 cm lateral to midline on the side of surgery. A local anesthetic skin wheal will be raised caudal to the ultrasound transducer. A 17-gauge, Tuohy-tip needle will be inserted through the skin wheal in-plane beneath the ultrasound transducer and directed to the paravertebral space. Normal saline (5 mL) will be injected via the needle to help identify the paravertebral space and observe the pleura being displaced anteriorly. 0.4 ml\kg of 0.25% Bupivacaine with epinephrine, 5 μg/mL, will be slowly injected with gentle aspiration every 3 mL.

Inclusion Criteria: unilateral mastectomy with or without axillary lymph node dissection. American Society of Anesthesia (ASA) I&II Exclusion Criteria: morbid obesity (body mass index > 40 kg/m2); renal insufficiency (creatinine > 1.5 mg/dL), current chronic analgesic therapy (daily use > 4 weeks), a history of opioid dependence, pregnancy, inability to communicate with the investigators or hospital staff, American Society of Anesthesia (ASA) III-IV

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