The goal of this observational study is to to evaluate the changes in cold sensitivity and the onset of sensory block after performing a thoracic ESP block. It reflects the time it takes for the local anaesthetic to spread into the paravertebral space leading to changes in cold sensitivity in the chest. The study population are patients undergoing simple quadrantectomy or partial resection with or without sentinel lymphnode removal, in the operating rooms of Santa Maria Goretti Hospital in Latina. This study is observational because it simply describes and records the effects of a procedure (the ESP block) on treated patients during a period of observation. Before surgery, unilateral thoracic ESP block (T4 level) with a sterile, ultrasound-guided technique will be performed. A timer will be started to mark the time for subsequent evaluations. At 1,3,5 and after every 5 minutes following the block up to 40 minutes or until induction of general anaesthesia, the cold sensitivity of the chest will be explored.