Thoracotomy for lung resection is deemed painful. Ketamine is now a renewed interest in preventing acute postoperative pain. A previous study performed in the service testing the association ketamine/morphine versus morphine PCA, postoperative, for patients who do not benefit from postoperative epidural thoracic surgery, has demonstrated a reduction of postoperative pain associated with a reduction of nocturnal arterial desaturation following surgery when ketamine was added to morphine.