Pectoral Nerve Block Versus Serratus Posterior Superior Intercostal Plane Block for Pain Control After Mastectomy

This prospective, randomized study will be conducted at Bursa City Hospital in adults undergoing elective mastectomy for breast cancer. Participants will be assigned to an ultrasound-guided serratus posterior superior intercostal plane (SPSIP) block or a pectoral nerve block (PECS II) using a computer-generated randomization sequence.

Both blocks will be performed before induction of general anesthesia. The SPSIP group will receive 30 mL of 0.25% bupivacaine in the fascial plane between the serratus posterior superior and intercostal muscles at the third rib. The PECS II group will receive 10 mL of 0.25% bupivacaine between the pectoralis major and pectoralis minor muscles and 20 mL between the pectoralis minor and serratus anterior muscles.

General anesthesia and postoperative multimodal analgesia will be standardized. On arrival in the recovery room, participants will receive intravenous patient-controlled analgesia with tramadol at a concentration of 5 mg/mL, a bolus dose of 10 mg, a lockout interval of 20 minutes, and no basal infusion. Intravenous meperidine at 0.5 mg/kg will be administered as rescue analgesia when the Numeric Rating Scale (NRS) score is 4 or higher.

Postoperative pain and opioid consumption will be assessed by an anesthesiologist who is unaware of group allocation. The clinician performing the block will know the assigned technique and will not collect postoperative outcome data.

NRS scores at rest and during movement will be recorded at 0, 2, 4, 8, 16, and 24 hours after surgery. The scale ranges from 0 (no pain) to 10 (the worst pain imaginable). Tramadol consumption will be recorded at the same time points. Rescue analgesic requirements, time to first rescue analgesia, time to first postoperative mobilization, length of hospital stay, adverse effects, and block-related complications will also be recorded.

Quality of recovery will be assessed using the Quality of Recovery-15 questionnaire at 24 hours after surgery. Postoperative nausea and vomiting will be monitored during the first 24 hours. Persistent postoperative pain will be assessed at 3 months using the McGill Pain Questionnaire during a telephone interview conducted with prior participant consent.

Participants will receive an ultrasound-guided SPSIP block on the surgical side before induction of general anesthesia. With the participant seated, 30 mL of 0.25% bupivacaine with epinephrine will be injected into the fascial plane between the serratus posterior superior and intercostal muscles at the third rib. Participants will also receive standardized general anesthesia and postoperative multimodal analgesia, including patient-controlled intravenous tramadol and rescue analgesia when required.

Other: Ultrasound-Guided Serratus Posterior Superior Intercostal Plane Block

Participants will receive an ultrasound-guided PECS II block on the surgical side before induction of general anesthesia. With the participant supine, 10 mL of 0.25% bupivacaine with epinephrine will be injected between the pectoralis major and pectoralis minor muscles, followed by 20 mL between the pectoralis minor and serratus anterior muscles. Participants will also receive standardized general anesthesia and postoperative multimodal analgesia, including patient-controlled intravenous tramadol and rescue analgesia when required.

Other: Ultrasound-Guided Pectoral Nerve Block Type II

A single ultrasound-guided block will be performed on the surgical side before induction of general anesthesia. With the participant seated and the hand on the opposite shoulder, a high-frequency linear ultrasound probe will be positioned along the medial scapular border to identify the third rib and serratus posterior superior muscle. A 50-mm block needle will be advanced in-plane in a caudal-to-cranial direction. After confirming the plane with 5 mL of saline, 30 mL of 0.25% bupivacaine with epinephrine will be injected between the serratus posterior superior and intercostal muscles.

A single ultrasound-guided PECS II block will be performed on the surgical side before induction of general anesthesia, with the participant supine. A high-frequency linear ultrasound probe will be used to identify the pectoralis major, pectoralis minor, and serratus anterior muscles. A 50-mm block needle will be advanced using an in-plane approach. After confirming each injection plane with 5 mL of saline, 10 mL of 0.25% bupivacaine with epinephrine will be injected between pectoralis major and pectoralis minor, followed by 20 mL of the same solution between pectoralis minor and serratus anterior.

Plazo: First 24 hours postoperatively, with recordings at 0, 2, 4, 8, 16, and 24 hours.

Postoperative opioid consumption will be compared between the groups. Tramadol consumption administered through intravenous patient-controlled analgesia will be recorded in milligrams at 0, 2, 4, 8, 16, and 24 hours postoperatively. The total dose of rescue meperidine will be recorded separately.

Plazo: At 0, 2, 4, 8, 16, and 24 hours postoperatively.

Pain intensity at rest will be assessed using the Numeric Rating Scale (NRS), ranging from 0 (no pain) to 10 (the worst pain imaginable). Higher scores indicate greater pain intensity.

Plazo: At 0, 2, 4, 8, 16, and 24 hours postoperatively.

Pain intensity during movement will be assessed using the Numeric Rating Scale (NRS), ranging from 0 (no pain) to 10 (the worst pain imaginable). Higher scores indicate greater pain intensity.

Plazo: During the first 24 hours postoperatively.

The total dose of intravenous meperidine administered as rescue analgesia will be recorded in milligrams. Meperidine at 0.5 mg/kg will be administered when the Numeric Rating Scale score is 4 or higher.

Plazo: During the first 24 hours postoperatively.

The time of the first postoperative administration of rescue analgesia will be recorded. Intravenous meperidine at 0.5 mg/kg will be administered when the Numeric Rating Scale score is 4 or higher.

Plazo: At 24 hours postoperatively.

Quality of postoperative recovery will be assessed using the Quality of Recovery-15 (QoR-15) questionnaire. The questionnaire contains 15 items, with a total score ranging from 0 to 150. Higher scores indicate better quality of recovery.

Plazo: During the first 24 hours postoperatively.

Postoperative nausea and vomiting will be assessed using a four-category scale: 1 = no nausea or vomiting; 2 = nausea without vomiting; 3 = one episode of vomiting or persistent nausea; and 4 = two or more episodes of vomiting or severe/persistent retching. Higher scores indicate more severe symptoms.

Plazo: At 3 months postoperatively.

Persistent postoperative pain will be assessed using the McGill Pain Questionnaire during a telephone interview at 3 months after surgery. Participants will provide prior consent for telephone follow-up.

Comparison of the Effects of Pectoral Nerve Block and Serratus Posterior Superior Intercostal Plane Block on Acute and Persistent Postoperative Pain After Mastectomy: A Prospective, Double-Blind, Randomized Controlled Trial