Postoperative pain remains a common clinical challenge in patients undergoing video-assisted thoracoscopic surgery (VATS), impairing early recovery and increasing opioid consumption. The serratus anterior plane block (SAPB) is a widely used regional analgesic technique for thoracic surgery, but conventional single-point injection may have limited spread of local anesthetics, resulting in suboptimal analgesia in some patients. Preliminary anatomical evidence suggests that two-point combined SAPB may achieve wider dermatomal coverage and better analgesic efficacy.

This is a single-center, prospective observational cohort study conducted at Shanghai Pulmonary Hospital, China. A total of 88 adult patients scheduled for elective unilateral VATS will be consecutively enrolled and naturally assigned to either the two-point combined SAPB group (injection at the 3rd and 5th rib levels, total 30 ml local anesthetic) or the single-point SAPB group (injection at the 5th rib level, 30 ml local anesthetic) according to routine clinical practice.

The primary outcome is the verbal rating scale (VRS) pain score on coughing at 24 hours postoperatively. Secondary outcomes include resting and dynamic pain scores at multiple time points, cumulative opioid consumption at 24 and 48 hours, incidence of postoperative nausea and vomiting, block-related complications, length of hospital stay, and Quality of Recovery-15 (QoR-15) scores. This study aims to provide clinical evidence for optimizing perioperative analgesic strategies for thoracoscopic surgery.

Study Background Video-assisted thoracoscopic surgery (VATS) is the standard minimally invasive approach for thoracic diseases, yet over 60% of patients experience moderate-to-severe postoperative pain within 24 hours, which impairs respiratory function, increases opioid consumption and prolongs hospital stay. The serratus anterior plane block (SAPB) is a widely used fascial plane block for thoracic analgesia, but conventional single-point injection often yields inconsistent anesthetic spread due to individual anatomical variations, resulting in suboptimal analgesia in some patients. Preliminary anatomical and clinical evidence suggests that two-point combined SAPB may achieve wider dermatomal coverage and superior analgesic efficacy, but confirmatory evidence in VATS patients remains limited.

Study Design & Population This is a single-center, prospective observational cohort study conducted at Shanghai Pulmonary Hospital, China. A total of 88 eligible patients aged 18-85 years with ASA physical status I-III, scheduled for elective unilateral VATS and planned for perioperative SAPB, will be consecutively enrolled. Patients will be naturally allocated to the two-point group or single-point group according to the clinical regimen chosen by the attending anesthesiologist, with no researcher-initiated randomization. Exclusion criteria include local infection at the puncture site, allergy to amide local anesthetics, chronic opioid use, severe coagulopathy, and cognitive impairment precluding pain assessment.

Interventions & Outcomes All blocks are performed under ultrasound guidance by anesthesiologists with ≥50 prior SAPB experiences. The two-point group receives 15 ml of local anesthetic at both the 3rd and 5th rib levels (total 30 ml); the single-point group receives 30 ml at the 5th rib level. Standardized general anesthesia and postoperative analgesia protocols are applied uniformly to all patients. The primary outcome is the verbal rating scale (VRS) pain score on coughing at 24 hours postoperatively. Secondary outcomes include resting and dynamic pain scores at multiple time points, cumulative opioid consumption at 24 and 48 hours, incidence of postoperative nausea and vomiting, block-related complications, length of hospital stay, and QoR-15 recovery quality scores.

Inclusion Criteria:

• Aged 18 to 85 years at enrollment, regardless of sex
• American Society of Anesthesiologists (ASA) physical status grade I to III
• Scheduled for elective unilateral video-assisted thoracoscopic surgery
• Planned to receive ultrasound-guided SAPB for routine perioperative analgesia
• Able to understand study procedures and provide written informed consent

Exclusion Criteria:

• Local infection or skin lesion at the block puncture site
• Known hypersensitivity or allergy to amide local anesthetics
• Preexisting sensory abnormality in the chest wall surgical area
• Chronic opioid use for > 3 months, history of chronic pain syndrome, or history of opioid abuse
• Severe coagulopathy (international normalized ratio > 1.5 or platelet count < 80 × 10⁹/L)
• Cognitive impairment or inability to cooperate with postoperative pain assessment
• Refusal to provide written informed consent

This single-center, prospective observational cohort study is conducted at Shanghai Pulmonary Hospital, Tongji University School of Medicine, China. It enrolls adults aged 18-85 years with ASA physical status I-III, scheduled for elective unilateral video-assisted thoracoscopic surgery and planned for ultrasound-guided serratus anterior plane block as routine perioperative analgesia.Eligible participants will be consecutively enrolled after written informed consent. Patients are naturally assigned to two cohorts based on the block regimen selected by the attending anesthesiologist in standard clinical practice, with a target total sample size of 88 (~44 per cohort). No study-initiated randomization or treatment intervention is applied; all clinical management follows institutional routine protocols.