Video-assisted thoracic surgery (VATS) has started to be considered the standard surgical procedure for lung surgery in recent years. The advantages of VATS compared to open thoracotomy are rapid recovery, shorter hospital stays, and low risk of complications. Although it is a less painful surgical procedure compared to thoracotomy, severe acute postoperative pain can be observed especially in the first hours after VATS. Thoracic epidural analgesia (TEA), which is the gold standard for post-thoracotomy analgesia, is used in analgesia after VATS. However, due to the difference in surgical technique and trauma between open surgery and VATS, what should be the gold standard for analgesia after VATS is a matter of debate. It is supported that less invasive analgesic techniques should be applied for minimally invasive surgical procedures, especially due to the difficulty of applying TEA and its side-effect profile. Thoracic paravertebral block (TPVB) is considered the first-line regional technique for VATS surgery. However, it is difficult to apply due to its anatomical proximity to important structures such as the pleura and central neuraxial system, and it may cause complications such as pneumothorax and vascular injury. Analgesia management is very important in these patients, as insufficient analgesia in the postoperative period may cause pulmonary complications such as atelectasis, pneumonia, and increased oxygen consumption.

Ultrasound (US) guided serratus posterior superior block (SPSPB) is a new interfacial plane block defined by Tulgar et al in 2023. It is based on injection on the serratus posterior superior muscle at the level of the 2nd or 3rd rib. This block provides analgesia in conditions such as interscapular pain, chronic myofascial pain syndromes, scapulocostal syndrome, and shoulder pain. The SPS muscle is located at the C7-T2 level. It attaches to the lateral edges of the second and fifth ribs. It is innervated by the lower cervical and upper intercostal nerves. With the SPS block, these nerves are blocked and analgesia is provided.

In the cadaveric study of Tulgar et al., it was determined that the spread of serratus posterior superior interfacial plane block; 7-10 intercostal levels on the left side only in the superficial fascia of the trapezius muscle. Spread dye was observed at intercostal levels, absent on the right. There was prominent staining on both sides of the deep trapezius muscle. Both the surface and skin of the rhomboid major were stained, while the rhomboid minor was only stained in the skin. SPSP block will provide successful analgesia in procedures involving the thoracic region such as chronic myofascial pain, breast surgery, thoracic surgery, and shoulder surgery. There is no randomized study in the literature evaluating the effectiveness of SPSP block for postoperative analgesia management after VATS.

US-guided serratus anterior plane (SAP) block is an interfascial plane block and was described by Blanco in 2013. A local anesthetic solution is performed into the fascial plane of the serratus anterior muscle. It is easy to perform and has low complication rate because it is far away from the important neurological and vascular structures. The serratus anterior muscle may be seen easily with US guidance in the mid-axillary line. It provides effective analgesia in anterior, posterior, and lateral dermatomes of the thorax. It has been reported that SAP block provides effective postoperative pain management following thoracotomy, breast surgery, and VATS. There is no clinical randomized study in the literature evaluating the efficacy of SPSIPB and SAP block following VATS.

This study aims to compare US-guided SPSIPB and SAP block for postoperative analgesia management after VATS. The primary aim is to compare postoperative opioid consumption and the secondary aims are to evaluate postoperative pain scores (NRS), adverse effects related with opioids (allergic reaction, nausea, vomiting) and complications due to blocks (pneumothorax, hematoma).