Comparison of Erector Spinae Plane Block With Serratus Anterior Plane Block for Breast Surgery

Preoperative preparation:

History taking, physical examination, and investigations will be done according to the local protocol designed to evaluate the patients. This includes complete blood count, blood sugar level, serum urea and creatinine, liver function tests, coagulation profile and electrocardiogram (ECG).

Before surgery, the participants will receive education about the VAS pain score (0-100 mm) (where0=no pain and 100 = worst comprehensible pain) and the details of the nerve block procedures. After 6 hours of fasting, the patients will be taken to the operation theatre.

Anesthetic management:

The patient will receive Midazolam 0.03 mg/kg intravenous (IV), Metoclopramide 10 mg IV, Ranitidine 50 mg IV and Cefotaxime 1 gm as a premedication.

Intravenous access will be obtained with an 18-gauge intravenous (IV) cannula in the contralateral upper limb of the surgical site and monitors (pulse oximeter, electrocardiography, non-invasive blood pressure (NIBP) and capnography) will be applied.

All patients will receive pre-oxygenation with 100% O2 for 3 min. Anesthesia will be induced by using fentanyl 1μg/kg, propofol 1.5-2 mg/kg and atracurium 0.5 mg/kg. Anesthesia will be maintained by controlled ventilation with oxygen and air (50:50) with target of End Tidal Carbon Dioxide Tension (EtCO2) ≈ 35-40 mmHg, isoflurane 1:1.5 minimum alveolar concentration (MAC), 0.5μg/kg fentanyl will be given intraoperatively when either heart rate or Non-Invasive Blood Pressure (NIBP) report an increase by more than 20% of the basal records. Anesthesia will be discontinued and tracheal extubation will be done once patient fulfilled the extubation criteria.

A high-frequency ultrasound probe Active Array L12-4 (8-13MHz) of an ultrasound machine (Philips clear vue350, Philips Healthcare, Andover MA01810™, USA).and a 22-gauge, 50 mm echogenic needle (Stimuplex D®; B Braun, Germany) will be used for performing the blocks.

Patients in group (S) will receive serratus anterior plane block and those in group (E) will receive Erector spinae plane block. Both of these blocks will be performed after induction of general anesthesia by an experienced anesthesiologist (who is well trained in ultrasound-guided regional anesthesia). After proper skin sterilization with povidone-iodine solution.

For the ultrasound-guided serratus anterior plane block, the patient will be placed in supine position with the arm abducted. Ribs will be counted in the mid-axillary line from downward upwards until the 5th ribs the linear probe will be placed horizontally then three muscles will be identified: latissimus dorsi (superficial and posterior), teres major (superior) and serratus muscles (deep and inferior) .the thoracodorsal artery (slightly posterior) will be used as extra guide in the identification of the plane superficial to the serratus muscle. The needle will be inserted in-plane with respect to the ultrasound probe from supero-anterior to postero-inferior. 0.5: 1 mL of non-active fluid will be injected to confirm correct needle tip position by visualizing spread over serratus anterior muscles, then a total 20 ml of bupivacaine 0.25% will be injected.

For the ultrasound-guided erector spinae plane block

At first the patient will be placed in a lateral decubitus with the operation site up. The vertebrae will be counted from cephalad to caudal direction until we reach T5 spinous process as the first palpable spinous process is C7. Ultrasound probe will be placed vertically 3 cm lateral to the T5 spinous process. Three muscles will be identified superficial to the hyperechoic transverse process shadow as follows:

trapezius, rhomboid major, and erector spinae. The needle will be introduced from superior to inferior direction in-plane until the tip lay deep to erector spinae muscle (the needle tip contacts the tip of the transverse process), 0.5: 1 mL of non-active fluid will be injected to confirm correct needle tip position by visualizing spread under erector spinae muscle a total of 20 mL of 0.25% bupivacaine will be injected next.

Post-operative care Patients will be transferred to post-anesthetic care unit (PACU) for 2 hrs after anesthesia emergence. The patients will be discharged from the PACU after fulfilling the discharge criteria based on the modified Aldrete score> 9 The patient will receive analgesic according to the local institutional protocol as the following (paracetamol 1gm IV infusion/8 hours, ketorolac 30 mg Intramuscular/12 hours) as 2 components of multimodal anesthesia regimen for postoperative pain control.

A postoperative rescue analgesia with morphine sulfate IV per a titration protocol (3 mg IV as a bolus dose which can be repeated every 5 minutes with a maximum dose of 15mg per 4 hours or 45mg per 24 hours) will be employed if visual analog pain scale (VAS) > 4. The morphine titration protocol will be suspended with Oxygen saturation < 95%; Respiratory rate < 10 / min; the development of sedation (Ramsay sedation scale >2); development of acute adverse effects (allergy, marked itching, excessive vomiting, and hypotension with systolic blood pressure less than 20% of baseline values); or attaining adequate level of analgesia.