Paravertebral Analgesia Associated With Intravenous Morphine PCA After Thoracotomy

osteolateral thoracotomy is a painful surgical procedure.Thoracic epidural analgesia (TEA) is usually considered as the "gold standard" for postoperative thoracic analgesia. Unfortunately, it's not always possible to realize it because of contraindications or because of technical failures.Analgesia using a paravertebral block is an alternative to the TEA : it provides an unilateral sensitive and sympathetic block using a catheter.In our study, the catheter will be placed by the thoracic surgeon at the end of the surgical procedure, under direct vision, to insure maximal security also on patients on antiplatelets agents, anticoagulants or with haemostasis disorders (the placement of the catheter by the anaesthetist with the loss of resistance technique is contraindicated in these cases).Patients will be randomized to receive either a continuous 48-hours infusion of ropivacaine 0,5% or saline serum in the control group.All patients are connected to a PCA pump with intravenous morphine and will receive paracetamol and nefopam.The visual analogic scale (VAS) at rest and on movement, total morphine consumption and side effects will be recorded during the first 48 hours after surgery. The aim of this study is to prove a decrease of pain at rest and on movement, a decrease of the cumulated total morphine dose consumption and a decrease of the side effects (nausea, vomiting, pruritus, sedation, bradypnea, urinary retention).