Prediction and Characterization of Acute and Chronic Postoperative Pain

Despite enormous progress insufficient postoperative pain management remains a frequent problem in the early postoperative phase after surgery. Furthermore, the pain that persists after healing of the surgical wound is a large, but often unrecognized, clinical problem and it is estimated that 5-10% of those undergoing surgery will develop severe persistent pain leading to chronic disability and psychosocial distress. Conditioned Pain Modulation (CPM), also known as the phenomenon "pain-inhibits-pain", is a reduction in pain somewhere on the body in response to the application of a second painful stimulus outside the painful area. In recent years, the CPM has been identified as a psycho-physical measure with clinical relevance in characterizing the individual's ability to modulate pain and consequently the individual's disposition to acquire painful conditions. The purpose of this study is primarily to assess the relationship between CPM efficacy and clinical postoperative pain (postoperative pain intensity, use of analgesics, the intensity of secondary hyperalgesia and allodynia, and the incidence of persistent postoperative pain) associated with minimally invasive repair of pectus excavatum. In addition, the study aims at identifying other patient- and/or surgery-related factors affecting the course of postoperative pain. Hypothesis: \- The greater the positive difference between the experimental pressure pain threshold (kPa) measured before and after application of a second painful stimulus (Cold Pressor Test), the lower the risk of developing persistent postoperative pain. Secondary hypotheses * The greater the positive difference between the experimental pressure pain threshold (kPa) measured before and after application of a different experimental painful stimulus (Cold Pressor Test) lower the pain intensity in the early postoperative period. * The greater the positive difference between the experimental pressure pain threshold (kPa) measured before and a