RESUMO
AIM: Epidural analgesia is considered to be the best method of pain relief after major surgery despite its side-effects, which include hypotension, respiratory depression, urinary retention, incomplete or failed block, and, in rare cases, paraplegia. Paravertebral block is an alternative technique that may offer a comparable analgesic effect and a better side-effect profile. This study measured postoperative pain and respiratory function in patients randomized to receive either paravertebral block or epidural analgesia for pain control after thoracic surgery. METHODS: Twenty-four adult patients undergoing thoracic surgery were enrolled in a prospective and randomized clinical study. Patients were randomly allocated to receive either postoperative continuous paravertebral analgesia (N=12) or epidural analgesia (N=12) starting at pleura closure. Postoperative use of morphine, visual analogue scores, and spirometer data were collected for 72 hours after surgery as markers of pain relief. RESULTS: There was a statistically significant (P=0.003) increase in median (25th-75th percentiles) patient-controlled use of morphine, with values of 36 (22-42) mg in the paravertebral group vs. 9 (2-22) mg in the epidural group. This increase in morphine usage in the paravertebral group was statistically significant at 6, 24, 48, and 72 hours after surgery. Postoperative pain measured with the visual analogue score was not significantly different in the two groups. Spirometer values at 72 h were better in the epidural group than in the paravertebral group (P=0.03). CONCLUSIONS: Epidural analgesia is more efficient than paravertebral continuous block at reducing pain after thoracic surgery.