Lung Ultrasound Detection of Perioperative Atelectasis in Orthopaedic Surgery: A Comparative Study of Regional versus General Anaesthesia

Objectives: To compare perioperative lung aeration loss after elective lower extremity orthopaedic surgery under regional versus general anaesthesia using a standardised 12-zone lung ultrasound (LUS) score and to evaluate its relationship with spirometry and arterial blood gas (ABG) outcomes.
Methods: In this prospective, single-centre observational study conducted at a tertiary care university hospital, 60 adults (ASA I–III) without pulmonary disease undergoing elective lower extremity orthopaedic surgery were allocated by clinical decision to receive combined spinal–epidural anaesthesia (n=30) or general anaesthesia (n=30). LUS, spirometry, and ABG on room air were performed preoperatively and within 2 hours postoperatively.
Results: Baseline characteristics and preoperative LUS scores were comparable between the groups (13.03±3.60 vs. 12.70±3.29). Postoperative aeration loss was significantly greater after general anaesthesia (ΔLUS 6.53±2.90) than after regional anaesthesia (ΔLUS 1.90±3.26), with a mean difference of 4.63 (95% CI 3.03–6.24; p<0.001; Cohen’s d=1.50). Clinically significant atelectasis (ΔLUS≥4) occurred more frequently in the general anaesthesia group (76.7% vs. 36.7%; absolute risk reduction, 40.0%; NNT, 2.5). Adjusted analysis confirmed an independent group effect (β=4.79; p<0.001; R²=0.513). Oxygenation did not differ between the groups and showed no correlation with ΔLUS. Small airway function declined more after general anaesthesia.
Conclusions: These findings suggest that regional anaesthesia may be associated with reduced perioperative lung aeration loss and support the potential role of LUS in perioperative monitoring. Further randomised controlled trials are warranted.

Keywords: Atelectasis, general anesthesia, postoperative complications, regional anesthesia, ultrasonography.