The efficacy of paravertebral block using a catheter technique for postoperative analgesia in thoracoscopic surgery: a randomized trial

Abstract

Objective: The analgesic scheme combining paravertebral block (PVB) and intravenous non-steroidal anti-inflammatory drug (NSAID) has proven to be effective for postoperative pain control after thoracotomy. The hypothesis tested in this study was that this policy was also suitable to improve pain control after video-assisted thoracic surgery (VATS).

Methods: This was a prospective randomized study on 40 patients submitted to three-ports' VATS for pneumothorax or solitary pulmonary nodule. The sample size was calculated to detect one point of minimum pain score difference with 80% statistical power. Patients were randomly assigned to two groups: (1) paravertebral block group (PVB) (n=20) - At the end of surgery, a catheter was placed in patients in the thoracic paravertebral space under camera control; they received a bolus of 15 ml of local anesthetic (ropivacaine 0.2%) every 6h, combined with endovenous metamizol (1g); and (2) alternate NSAIDs group (AN) (n=20) - They were treated with paracetamol (1g) combined with metamizol (1g) every 6h. Subcutaneous meperidine (synthetic opioid) was employed as rescue drug. Both groups were comparable in terms of age, sex, pathology, and co-morbidity. Pain level was measured with the visual analog scale (VAS) at 1, 6, 24, and 48 h.

Results: No side effects related to any of the two analgesic techniques were noted. Two patients needed rescue meperidine in the AN group, and none in the PVB group. VAS scores were the following: PVB group, VAS 1h: 1.4±0.8, VAS 6h: 3.4±1.2, VAS 24h: 2.6±1.0, VAS 48 h: 2.2±0.9, and mean VAS: 2.4±1.3; AN group, VAS 1h: 2.8±1.0, VAS 6h: 4.9±1.3, VAS 24h: 3.9±1.4, VAS 48 h: 3.3±1.0, and mean VAS: 3.8±1.4. VAS scores were significantly lower at any time in the PVB patients (p<0.01).

Conclusions: The analgesic regimen combining PVB and NSAID provided an excellent level of pain control. Thoracoscopy assisted positioning of the paravertebral catheter is simple and effective, and allows direct visualization of correct delivery of local anesthetic. It represents a valuable addition to any VATS procedure.