This prospective, randomized, controlled clinical trial aims to compare the effects of two ultrasound-guided fascial plane blocks, the Erector Spinae Plane Block (ESPB) and the Modified Thoracoabdominal Nerve Block through Perichondrial Approach (M-TAPA), on postoperative pulmonary function and analgesic consumption in patients undergoing laparoscopic cholecystectomy. Laparoscopic cholecystectomy is one of the most frequently performed abdominal surgical procedures worldwide. Despite minimally invasive techniques, postoperative pain remains a significant clinical problem due to port-site trauma, pneumoperitoneum, diaphragmatic irritation, and visceral manipulation.

Inadequate pain control may lead to impaired respiratory mechanics, reduced mobilization, delayed recovery, and an increased risk of postoperative pulmonary complications. Postoperative pulmonary dysfunction is a common consequence of upper abdominal surgery and may persist for several days, contributing to reductions in forced vital capacity (FVC) and forced expiratory volume in one second (FEV1), which are associated with increased postoperative morbidity.

Although opioid-based analgesia is widely used, it is associated with adverse effects such as respiratory depression, nausea, vomiting, ileus, and delayed recovery. Therefore, regional anesthesia techniques and multimodal analgesia strategies are increasingly recommended to reduce opioid consumption while improving pain control.

ESPB and M-TAPA are ultrasound-guided fascial plane blocks used for postoperative analgesia in abdominal surgery. ESPB provides somatic and visceral analgesia through the spread of local anesthetic affecting the spinal nerve rami, while M-TAPA targets the anterior branches of the thoracoabdominal nerves to provide extensive anterior and lateral abdominal wall analgesia.

Despite their increasing use, there is limited high-quality comparative evidence evaluating the effects of ESPB and M-TAPA on postoperative pulmonary function and opioid consumption in laparoscopic cholecystectomy. This study compares these two regional anesthesia techniques in a randomized controlled design to evaluate their impact on postoperative respiratory function and analgesic requirements.

This study is a prospective, randomized, controlled clinical trial designed to compare the effects of two ultrasound-guided fascial plane blocks, the Erector Spinae Plane Block (ESPB) and the Modified Thoracoabdominal Nerve Block through Perichondrial Approach (M-TAPA), on postoperative pulmonary function and analgesic consumption in patients undergoing laparoscopic cholecystectomy.

A total of 60 patients will be randomly allocated into two groups: ESPB group (n=30) and M-TAPA group (n=30). All patients will undergo standard general anesthesia. After induction of general anesthesia and before surgical incision, regional blocks will be performed.

Patients in the ESPB group will receive bilateral ultrasound-guided erector spinae plane block at the T9 vertebral level using 0.25% bupivacaine, 20 mL per side (total 40 mL). Patients in the M-TAPA group will receive bilateral ultrasound-guided modified thoracoabdominal nerve block through the perichondrial approach using the same concentration and volume of local anesthetic (0.25% bupivacaine, total 40 mL).

All blocks will be performed under sterile conditions using a high-frequency linear ultrasound probe and an 80 mm echogenic needle.

All patients will receive standardized multimodal analgesia, including intravenous paracetamol (1 g every 8 hours) and intravenous ibuprofen (400 mg every 12 hours) for 24 hours postoperatively. The first doses of paracetamol and ibuprofen will be administered 10 minutes before the end of surgery.

Postoperative pain will be assessed using the Numeric Rating Scale (NRS) at rest and during movement at 1, 6, 12, 18, and 24 hours after surgery. Patient-controlled analgesia (PCA) with morphine will be used for postoperative analgesia. The PCA device will be set to deliver 1 mg morphine boluses with a lockout interval of 15 minutes and a maximum dose of 96 mg within 24 hours. Rescue analgesia with intravenous fentanyl (25 mcg) will be administered in patients with persistent pain (NRS ≥4 despite PCA bolus).

Total opioid consumption will be calculated as cumulative morphine consumption within the first 24 postoperative hours.

Pulmonary function tests will be performed preoperatively and at 1, 6, and 24 hours postoperatively, including forced vital capacity (FVC), forced expiratory volume in one second (FEV1), FEV1/FVC ratio, and peak expiratory flow (PEF).

Postoperative recovery quality will be evaluated using the Quality of Recovery-15 (QoR-15) questionnaire at 24 hours after surgery.

Inclusion Criteria:

• Patients aged 18-70 years
• American Society of Anesthesiologists (ASA) physical status I-III
• Patients scheduled for elective laparoscopic cholecystectomy
• Patients who provide written informed consent
• Patients who are able to cooperate and perform pulmonary function tests (PFTs)

Exclusion Criteria:

• Coagulation disorders or anticoagulant therapy contraindicating regional anesthesia
• Infection at the planned block site
• Known allergy to local anesthetic agents
• Conversion to open surgery
• Hemodynamic instability
• Inability to cooperate with pulmonary function tests (PFTs)
• Pre-existing severe pulmonary disease (e.g., severe chronic obstructive pulmonary disease or restrictive lung disease)
• Chronic opioid use or opioid dependence
• Pregnancy or breastfeeding
• Active smokers
• Body mass index (BMI) > 35 kg/m²

Anonymized participant-level data, including demographic variables, pulmonary function tests, pain scores, opioid consumption, and QoR-15 outcomes, may be shared upon reasonable request.