This prospective randomized controlled study aims to evaluate the effects of preoperative ultrasound-guided erector spinae plane (ESP) block combined with low-flow anaesthesia on postoperative quality of recovery and opioid consumption in patients undergoing elective laparoscopic cholecystectomy. The study will compare postoperative recovery quality, pain scores, analgesic requirements, and perioperative outcomes between patients receiving ESP block with low-flow anaesthesia and those receiving standard anaesthetic management.

Laparoscopic cholecystectomy, despite its minimally invasive nature, is associated with significant postoperative pain. This pain originates from multiple mechanisms, including somatic pain related to trocar insertion sites, visceral pain caused by gallbladder bed manipulation, and referred shoulder pain secondary to diaphragmatic irritation. Due to this heterogeneous pain profile, single-modality analgesic approaches are often insufficient, making multimodal analgesia strategies necessary.

Patient-centered outcome measures have become increasingly important in the evaluation of postoperative recovery. The Quality of Recovery-15 (QoR-15) score is a validated recovery assessment tool that evaluates not only pain but also physical comfort, emotional state, physical independence, and overall patient satisfaction. Therefore, QoR-15 is considered a clinically meaningful primary outcome measure in anaesthesia research.

Ultrasound-guided erector spinae plane (ESP) block is a modern regional anaesthesia technique that provides analgesia through cranio-caudal spread of local anaesthetic within the fascial plane deep to the erector spinae muscle, affecting both dorsal and ventral spinal rami. When performed at thoracic levels, particularly between T6 and T9, ESP block may provide effective somatic and visceral analgesia for laparoscopic cholecystectomy.

Previous randomized controlled studies have demonstrated that ESP block reduces postoperative pain scores, opioid consumption, and postoperative nausea and vomiting in patients undergoing laparoscopic cholecystectomy. Furthermore, recent studies have shown improved postoperative recovery quality assessed by QoR-15 scores in patients receiving ESP block.

Low-flow anaesthesia is a modern inhalational anaesthesia technique based on reducing fresh gas flow and rebreathing exhaled gases. This approach decreases volatile anaesthetic consumption, improves cost-effectiveness, and reduces environmental impact. In addition, low-flow anaesthesia may provide physiological advantages such as preservation of airway humidity and temperature, improved mucociliary function, and maintenance of respiratory stability.

Several clinical studies have demonstrated the safety and physiological benefits of low-flow anaesthesia, including reduced volatile anaesthetic consumption while maintaining hemodynamic stability and adequate anaesthetic depth.

Although both ESP block and low-flow anaesthesia have individually been shown to provide beneficial perioperative effects, there is currently no prospective controlled study evaluating the combined effects of these two approaches on postoperative recovery quality and opioid consumption in laparoscopic cholecystectomy patients.

This prospective randomized controlled study aims to evaluate whether the combination of preoperative ultrasound-guided ESP block and low-flow anaesthesia improves postoperative quality of recovery and reduces opioid requirements in patients undergoing elective laparoscopic cholecystectomy.

Inclusion Criteria:

• Patients aged 18-65 years
• ASA physical status I-II
• Body mass index (BMI) <35 kg/m²
• Scheduled for elective laparoscopic cholecystectomy
• Ability to provide written informed consent

Exclusion Criteria:

• Coagulopathy or bleeding disorders
• Allergy to local anaesthetic agents
• Infection at the block application site
• Neurological or psychiatric disorders
• Communication difficulties
• Chronic opioid or analgesic use
• Reoperation cases
• Acute cholecystitis
• Conversion to open surgery
• Inadequate dermatomal block after ESPB
• Severe intraoperative hemodynamic instability
• Intraoperative blood loss ≥250 mL
• Development of allergic reactions or major complications during follow-up

Individual participant data will not be shared publicly in order to protect participant confidentiality and institutional data privacy policies.