This prospective randomized controlled trial evaluates the efficacy and safety of ultrasound-guided rhomboid intercostal and subserratus plane (RISS) block for postoperative analgesia in patients undergoing video-assisted thoracoscopic surgery (VATS).

Postoperative pain after VATS can impair respiratory function, delay mobilization, and increase opioid consumption. Although several regional anesthesia techniques are available, the optimal analgesic strategy remains under investigation. The RISS block is a novel fascial plane block that may provide effective thoracic analgesia while minimizing opioid-related adverse effects.

A total of 90 adult patients scheduled for elective VATS will be randomly assigned to receive either ultrasound-guided RISS block combined with general anesthesia or general anesthesia alone. The primary outcomes include postoperative 24-hour benefit of analgesia score (BCS) and patient-controlled intravenous analgesia (PCIA) pressing frequency. Secondary outcomes include postoperative pain scores, opioid consumption, and adverse events.

This study aims to determine whether RISS block improves postoperative recovery and reduces opioid requirements after VATS.

Inclusion Criteria:

Adults aged 18 years or older

ASA physical status I-II

Scheduled for elective video-assisted thoracoscopic surgery (VATS)

Provided written informed consent

Exclusion Criteria:

History of shock or coma

Coagulopathy

Local infection at the puncture site

Pre-existing nerve injury on the side intended for block

Chronic analgesic use

Psychiatric disorders

Prior thoracic or breast surgery

Allergy to local or general anaesthetic agents

Body mass index (BMI) ≥35 kg/m²

Inability to operate a patient-controlled analgesia (PCA) device