Video assisted thoracic surgery (VATS) has recently been evaluated as the standard surgical procedure for lung surgery. The advantages of VATS procedures compared with open thoracotomy are rapid recovery, short hospital stay and low complication risk. Although VATS is less painful than thoracotomy, patients may feel severe pain during the first hours at postoperative period. Thoracic epidural analgesia (TEA) which is the gold standard analgesic technique after thoracotomy, is generally used for analgesia management after VATS. However, since the surgical technique and trauma between open surgery and VATS are different, the question of what should be the gold standard for analgesia management after VATS is a topic of discussion. Especially due to the difficult administration and adverse effect profile of TEA, the opinion of minimally invasive surgical procedures, requiring less invasive analgesic techniques is supported. Thoracic paravertebral block (TPVB) has been evaluated as the first step regional analgesia technique for postoperative analgesia management after VATS. However, its administration is difficult because of its anatomical proximity to important structures such as the pleura and central neuro-axial system and it can cause complications such as pneumothorax, vascular injury. Analgesia management is very important for these patients in postoperative period since insufficient analgesia can cause pulmonary complications such as atelectasis, pneumonia and increased oxygen consumption.

The ultrasound (US) guided erector spina plane (ESP) block is a novel interfacial plan block defined by Forero et al. at 2016. ESP block provides thoracic analgesia at T5 level and abdominal analgesia at T7-9 level. The ESP block contains a local anesthetic injection into the deep fascia of erector spinae. This area is away from the pleural and neurological structures and thus minimizes the risk of complications due to injury. Visualization of sonoanatomy with US is easy, and the spread of local anesthesic agents can be easily seen under the erector spinae muscle. Thus, analgesia occurs in several dermatomes with cephalad-caudad way. Cadaveric studies have shown that the injection spreads to the ventral and dorsal roots of the spinal nerves and creates sensory blockade in both posterior and anterolateral thorax. In the literature, it has been reported that ESP block provides effective analgesia after open heart surgery, breast surgery and ventral hernia repair in randomized controlled studies about ESP block efficiency for postoperative analgesia management. In some case series and case reports it has been reported that ESP block provides effective analgesia after thoracotomy and VATS. Furthermore, it has been reported that it provides effective analgesia in chronic and persistant pain syndromes of thorax.

The aim of this study is to compare US-guided ESP block and TPVB for postoperative analgesia management after VATS. The primary aim is to compare perioperative and postoperative opioid consumption and the secondary aim is to evaluate postoperative pain scores (VAS), adverse effects related with opioids (allergic reaction, nausea, vomiting) and complications due to blocks (pneumothorax, hematoma).