Comparison of the Effectiveness of Interscalene Nerve Block and Serratus Posterior Superior Intercostal Plane Block in Patients Undergoing Arthroscopic Shoulder Surgery

Background/Objectives: Shoulder arthroscopies are commonly conducted in orthopedic practice. The interscalene brachial plexus block (ISB) is regarded as the “gold standard” for postoperative analgesia in shoulder surgeries. The serratus posterior superior intercostal plane block (SPSIPB) was introduced as an innovative treatment for addressing thoracic and shoulder discomfort. This study aims to examine the effects of SPSIPB and ISB techniques on postoperative pain levels, opioid intake, and respiratory function measures in patients having shoulder arthroscopy. Methods: Patients were divided into two groups. In the ISB group, 15 mL of fluid containing 0.25% bupivacaine was applied between interscalene muscles, while in the SPSIPB group, 30 mL of 0.25% bupivacaine was applied in the fascial plane between the serratus posterior superior muscle and the intercostal muscles. Results: There were no statistically significant differences in demographic characteristics (p > 0.05). VAS scores were statistically lower in the ISB group compared to the SPSIPB group at rest at 1, 2, 4, 8, 12, and 24 h postoperatively in the PACU (p < 0.05). VAS scores were also lower in the ISB group compared to the SPSIPB group during active movement at 1, 2, 4, 8, and 12 h postoperatively in the PACU (p < 0.05). Twenty-four-hour fentanyl consumption was lower in the ISB group compared to the SPSIPB group (407.50 ± 169.32 μg and 767.50 ± 178.00 μg, respectively, p < 0.001). The decrease in FEV1 and FVC was higher in the ISB group compared to the SPSIPB group (p < 0.001). Conclusions: ISB effectively relieves pain during shoulder arthroscopic procedures; however, while SPSIPB is considered a more advantageous option in terms of respiratory safety, it may not provide adequate analgesia on its own.