A PROSPECTIVE, RANDOMIZED COMPARISON OF INTERPLEURAL AND PARAVERTEBRAL ANALGESIA IN THORACIC-SURGERY

We have undertaken a prospective, randomized comparison of the superfi cially similar techniques of interpleural and paravertebral (extrapleu ral) analgesia in 53 patients undergoing posterolateral thoracotomy. L ocal anaesthetic placed anterior to the superior costotransverse ligam ent and posterior to the parietal pleura produces a paravertebral bloc k and instilled between the parietal and visceral pleurae produces an interpleural block. Patients received preoperative and postoperative c ontinuous bupivacaine paravertebral blocks in group 1 and interpleural blocks in group 2. Premedication comprised diclofenac and morphine, a nd after operation all patients had regular diclofenac and patient-con trolled morphine (PCM). Analgesia was assessed by visual analogue pain scores (VAS), PCM requirements, ratio of preoperative to postoperativ e spirometric values (PFT), rates of postoperative respiratory morbidi ty (FORM) and hospital stay, all recorded by blinded observers. Eight patients were withdrawn and data from 45 patients were analysed. Patie nt characteristics, surgery, VAS scores and PCM use were similar in bo th groups. PFT were significantly better (P = 0.03-0.0001) in group 1, and FORM was lower and hospital stay approximately 1 day less in this group. Five patients in group 2 became temporarily confused, probably because of bupivacaine toxicity (P = 0.02). We conclude that bupivaca ine deposited paravertebrally produced greater preservation of lung fu nction and fewer side effects than bupivacaine administered interpleur ally.