A randomized prospective study of analgesic quality after thoracotomy: paravertebral block with bolus versus continuous infusion with an elastomeric pump.

OBJECTIVES

Paravertebral block (PVB) with infusion of local anaesthetic (LA) through a paravertebral catheter is an effective alternative to epidural analgesia in the management of post-thoracotomy pain. PVB can be done in two ways: either through administration of a bolus dose of the LA or continuous infusion via an infusion pump; currently, there is no consensus on which route is best. Our objective was to compare the efficacy of the PVB for post-thoracotomy pain control using bolus doses versus a continuous infusion pump.

METHODS

We performed a prospective randomized study of 80 patients submitted to thoracotomy. Patients were divided into two independent groups (anterior thoracotomy--ANT--and posterolateral thoracotomy-POST). At the conclusion of the surgery, a catheter was inserted under direct vision in the thoracic paravertebral space at the level of the incision. In each group, patients were randomized to receive levobupivacaine 0.5% every 6 h ('Bolus' group) or levobupivacaine 0.25% in continuous infusion at 5 ml/h through an elastomeric pump ('Continuous infusion' group). Patients in both groups received the same dosage of LA: 300 mg/day. Metamizole (every 6 h) was administered as an adjunct. Subcutaneous meperidine was employed as a rescue medication. Pain scores were measured using the visual analogue scale (VAS) at 1, 6, 24, 48 and 72 h after surgery.

RESULTS

Thirteen (16.2%) patients required meperidine for rescue (8 in continuous infusion and 5 in the bolus group). Mean VAS scores were the following: all the cases (n = 80): 5.0 ± 1.6, ANT (n = 36): 4.4 ± 1.8, POST (n = 44): 5.4 ± 1.6, Bolus (n = 40): 4.7 ± 1.7, Continuous infusion (n = 40): 5.2 ± 1.8, ANT with bolus (n = 18): 4.1 ± 1.7, ANT with continuous infusion (n = 18): 4.7 ± 1.8, POST with bolus (n = 22): 5.2 ± 1.5, POST with continuous infusion (n = 22): 5.6 ± 1.6.

CONCLUSIONS

Post-thoracotomy pain control using a combination of PVB and a non-steroidal anti-inflammatory drug is a safe and effective approach. Patients submitted to ANT experienced less pain than those with POST 4.4 vs 5.4 (P = 0.02). Since no statistical differences were observed, it was not possible to confirm differences between the LA administered in a bolus versus continuous infusion.