Erector Spinae Plane Block Versus Subcostal Transversus Abdominis Plane Block Under Skin Conductance Algesimeter Guidance in Laparoscopic Gynecologic Oncologic Surgery

Female patients aged 18-65 years with ASA physical status I-III scheduled for elective laparoscopic gynecologic oncologic surgery were randomized in a 1:1 ratio using a computer-generated list (Research Randomizer) to the ESP group or the subcostal TAP group. General anesthesia was induced with fentanyl 0.5 µg/kg, propofol 2.5 mg/kg, and rocuronium 0.6 mg/kg and maintained with sevoflurane at approximately 1 minimum alveolar concentration. After induction and before surgical incision, blocks were performed under ultrasound guidance by experienced anesthesiologists with 20 mL of 0.25% bupivacaine on each side (total 40 mL): bilateral ESP block at the T9 level in the lateral decubitus position, or bilateral subcostal TAP block at the midclavicular line below the costal margin in the supine position.

Remifentanil infusion was started at 0.05-0.2 µg/kg/min and titrated according to the SCA index: decreased by 0.025 µg/kg/min when the index was 0-1, maintained when it was 3, and increased by 0.025-0.05 µg/kg/min when it was above 3, with at least 5 minutes between dose changes. The infusion could be reduced to zero when the SCA index remained at 0-1. Heart rate, blood pressure, SCA index, and bispectral index (BIS) were recorded at baseline, after intubation, every 15 minutes during surgery, and before and after extubation. All patients received intravenous dexketoprofen 50 mg and paracetamol 1 g approximately 30 minutes before the end of surgery.

Postoperative pain was assessed with the Numeric Rating Scale (NRS) at 0, 2, 4, 6, 12, 18, and 24 hours. Tenoxicam was given for NRS ≥4 and tramadol for NRS ≥7 as rescue analgesics. The Quality of Recovery-15 (QoR-15) questionnaire was administered preoperatively and at 24 hours postoperatively. Intraoperative data and postoperative follow-up were recorded by investigators who did not perform the blocks.

Bilateral ultrasound-guided erector spinae plane block at the T9 level with 20 mL of 0.25% bupivacaine on each side, performed after induction of general anesthesia and before surgical incision. Intraoperative remifentanil infusion titrated according to the skin conductance algesimeter index.

Other: Erector spinae plane block

Bilateral ultrasound-guided subcostal transversus abdominis plane block with 20 mL of 0.25% bupivacaine on each side, performed after induction of general anesthesia and before surgical incision. Intraoperative remifentanil infusion titrated according to the skin conductance algesimeter index.

Other: Subcostal transversus abdominis plane block

Procedure: Erector spinae plane block - Ultrasound-guided bilateral ESP block at T9 with 20 mL of 0.25% bupivacaine per side. Arm: ESP Group.

Procedure: Subcostal transversus abdominis plane block - Ultrasound-guided bilateral subcostal TAP block at the midclavicular line with 20 mL of 0.25% bupivacaine per side. Arm: Subcostal TAP Group.

Plazo: from induction of anesthesia to the end of surgery.

Total intraoperative remifentanil consumption - Total amount of remifentanil (µg) administered under skin conductance algesimeter guidance.

Plazo: 0, 2, 4, 6, 12, 18, and 24 hours postoperatively.

Time to first rescue analgesic - Time from extubation to the first rescue analgesic administration (minutes). Time frame: first 24 postoperative hours.

Plazo: 0, 2, 4, 6, 12, 18, and 24 hours postoperatively.

Rescue analgesic requirement - Number of patients receiving rescue analgesics (tenoxicam or tramadol). 0, 2, 4, 6, 12, 18, and 24 hours postoperatively.

Plazo: 0, 2, 4, 6, 12, 18, and 24 hours postoperatively.

Postoperative pain scores - Numeric Rating Scale (0 = no pain, 10 = worst imaginable pain).

Plazo: Time frame: preoperatively and 24 hours postoperatively.

Quality of recovery - Quality of Recovery-15 (QoR-15) score (0-150; higher scores indicate better recovery).

Comparison of the Analgesic Efficacy of Bilateral Subcostal Transversus Abdominis Plane Block and Bilateral Erector Spinae Plane Block Guided by Skin Conductance Algesimeter Pain Monitoring in Laparoscopic Gynecologic Oncologic Surgery: A Prospective Randomized Study