Comparison of Ultrasound-Guided Two-Point Combined vs Single-Point Serratus Anterior Plane Block for Postoperative Analgesia in Thoracoscopic Surgery: A Prospective Observational Cohort Study

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.