Purpose of the study The goal of this research is to see which of two nerve-numbing techniques-the Rhomboid-Intercostal Block (RIB) or the Thoracic Paravertebral Block (PVB)-works better to control pain after chest surgery (specifically, video-assisted thoracoscopic surgery, or VATS). Both techniques use numbing medication to block pain signals after the operation.

Who can participate? The researchers are looking for adults between 18 and 85 years old who are scheduled for a specific type of chest surgery (a 3-port VATS procedure).

How will the research happen? Participants will be put into two equal groups by chance. One group will receive the RIB technique, and the other group will receive the PVB technique. Both procedures are done under ultrasound guidance after the completion of surgery, while the patient is still asleep. The pain levels of the participants will be measured at rest and when taking deep breaths at several times during the first 24 hours after surgery.

Why is this study useful? This study aims to find out which pain relief method is more effective and if one results in fewer side effects, such as nausea or the need for stronger pain medications (opioids). These results will possibly help doctors provide better comfort to patients recovering from chest surgery in the future.

This study is a prospective, double-blind, randomized controlled trial evaluating the analgesic efficacy of two regional anesthesia techniques for patients undergoing elective 3-port Video-Assisted Thoracoscopic Surgery (VATS).

Procedure and Technique Following the induction of general anesthesia, participants are randomized (1:1) to receive either a Rhomboid-Intercostal Block (RIB) or a Thoracic Paravertebral Block (PVB) under ultrasound guidance.

Rhomboid-Intercostal Block (RIB): An injection of 30 ml of 0.375% Ropivacaine is administered in the plane between the rhomboid major and intercostal muscles at the T5 level.

Thoracic Paravertebral Block (PVB): An injection of 30 ml of 0.375% Ropivacaine is administered into the thoracic paravertebral space at the T5 and T7 levels.

Postoperative Clinical Management Pain intensity is monitored postoperatively. If a participant reports a Numerical Rating Scale (NRS) score greater than 4, a rescue analgesia protocol is initiated. This protocol consists of a bolus of intravenous (IV) Morphine (0.5 mg/kg). The investigators re-evaluate the NRS score after 20 minutes; if the score remains above 4, the dose is repeated. The investigators also monitor participants for potential complications, including hypotension, respiratory depression, and nausea/vomiting, throughout the 24-hour postoperative period.

Statistical Analysis Plan Pain scores across time points will be analyzed using a mixed-effects model or repeated measures ANOVA. Categorical data will be compared using the Chi-square test (χ^2). For continuous data, the distribution will be verified via the Kolmogorov-Smirnov test before applying the Student's t-test or the Wilcoxon signed-rank test as appropriate.

Inclusion Criteria:

• Adults (18-85 years old),
• ASA physical status I-III
• scheduled for elective 3-port unilateral VATS.

Exclusion Criteria:

• Allergy to local anesthetics
• infection at the injection site
• coagulation disorders
• severe neurological disorder
• obesity (BMI > 35)
• opioid addiction
• conversion to open thoracotomy, admission to ICU.

all IPD collected throughout the trial, only IPD used in the results publication