Comparing Erector Spinae Plane (ESP) and Thoracic Paravertebral (TPV) Block Analgesic Effect After Elective VATS

US guided ESP infiltration (saline solution vs Ropivacaine 0.375% according to randomization): unilateral injection of 0,4 ml kg -1 (ideal weight)2 under US guidance between the deep fascia of erector spinae muscle and the two transverse processes at the level of the 5th thoracic vertebrae. Duration approximately 10-15 minutes