Acute and Chronic Pain, Especially Neuropathic Pain, After Thoracotomy and Continuous Application of Ketamine.

Chronic Pain, especially neuropathic pain, are adverse events after posterolateral thoracotomy for lung resection. The continuous application of ketamine may have a prophylactic effect and helps to prevent chronic pain. The investigators record the incidence and severity of acute pain and neuropathic pain during a seven day period after thoracotomy as well as the incidence of chronic pain and neuropathic pain after one and three month period. Parallel Group design, comparing one Group with a continuous application (24 hours) of ketamine against a Placebo Group.