A prospective study of analgesic quality after a thoracotomy: paravertebral block with ropivacaine before and after rib spreading.

摘要

OBJECTIVE: Paravertebral block (PVB) is an effective alternative to epidural analgesia in the management of post-thoracotomy pain. Rib spreading (RS) is an important noxious stimulus considered a major cause of post-thoracotomy pain. Our hypothesis was that a bolus of ropivacaine 0.2% through a paravertebral catheter (PVC) inserted before RS could decrease pain during the first 72 postoperative hours. METHODS: The methodology employed was to perform a prospective randomised study of 60 consecutive patients submitted to thoracotomy. Patients were divided in two independent groups (anterior thoracotomy (AT) and posterolateral thoracotomy (PT)). A catheter was inserted under direct vision in the thoracic paravertebral space at the level of incision. In each group, patients were randomised to receive a bolus of 20 ml of ropivacaine 0.2% before rib spreading (pre-RS) or after (post-RS), just before closing the thoracotomy. They postoperatively received 15 ml of ropivacaine 0.2% every 6 h combined with methamizol (every 6h). Subcutaneous meperidine was employed as a rescue drug. The level of pain was measured with the visual analogue scale (VAS) at 1, 6, 24, 48 and 72 h after surgery. The need of meperidine as a rescue drug and secondary effects were also recorded. RESULTS: We did not register secondary effects in relation to the PVC (paravertebral or cutaneous bleeding or haematoma, respiratory depression, cardiotoxicity, confusion, sedation, urinary retention, nausea, vomiting or pruritus). Seven patients (11.6%) needed meperidine as rescue drug (four pre-RS and three post-RS). The mean VAS values were the following: all cases (n=60): 4.7+/-2.0; AT (n=32): 4.0+/-2.1; PT (n=28): 5.6+/-1.8; pre-RS (n=30): 4.8+/-1.9; post-RS (n=30): 4.6+/-2.0; AT-pre-RS (n=16): 4.1+/-2.0; AT-post-RS (n=16): 3.9+/-2.1; PT-pre-RS (n=14): 5.6+/-1.6; PT-post-RS (n=14): 5.4+/-1.7. CONCLUSIONS: Post-thoracotomy analgesia combining PVC and a non-steroidal anti-inflammatory drug is a safe and effective practice. VAS values are acceptable (only 11.6% of patients required meperidine). It prevents the risk of side effects related to epidural analgesia. Patients submitted to AT experienced less pain than those with PT (4.0 vs 5.6; p<0.01). PVB with ropivacaine before RS got similar VAS values than the block after RS (4.8 vs 4.6; p>0.05). The moment of the insertion of the PVC does not seem to affect postoperative pain levels.