In Reply:—
The search for the optimal pain management technique after thoracoscopic surgery remains a clinically important undertaking. Although I support the enthusiasm of Drs. Ben-David, Merman, and Chelly for the development of safe and effective postoperative analgesia, I disagree with their assessment of our clinical trial. Because the mode for hospital length of stay in my institution after thoracoscopic surgery is 1 day, we evaluated single-dose, multilevel paravertebral nerve blockade in a randomized, double-blind, placebo-controlled clinical trial using postoperative patient-controlled morphine usage as our primary endpoint. We found a significant reduction in narcotic requirement for the first 6 h after block placement, but the benefit did not persist. Therefore, we concluded, “Single-dose paravertebral nerve blockade with bupivacaine is effective in reducing pain following thoracoscopic surgery, but only during the first 6h after nerve blockade. Due to the limited duration of effect with currently available local anesthetic agents, our data suggest that, at present, this technique is not indicated in the setting of thoracoscopic surgery.”1We did not study continuous paravertebral local anesthetic infusion, nor did we conclude that this technique would be ineffective.
Whereas I support continued study of paravertebral catheter placement with continuous local anesthetic infusion, I caution against advocacy for a therapeutic intervention with associated risk and expense based on clinical experience in a series of patients without adequate study in a randomized, double-blind, placebo-controlled clinical trial. Before our trial, I was enthusiastic about the technique and was of the opinion that the results of the study would be unequivocally positive. I had observed that patients seemed to wake up with less pain and required less narcotic administration in the recovery area. Although these observations proved to be correct, patients were less comfortable after leaving the recovery room. From 6 to 12 h after nerve blockade, the treatment group used more patient-controlled morphine than the control group, making the cumulative morphine dose indistinguishable between groups by the 12th h. Although morphine usage may be an imperfect endpoint, we were unable to explain the increased narcotic requirement in any way other than loss of paravertebral block efficacy. Although adverse events were mild and similar between groups, increased narcotic usage by patients undergoing pulmonary resection after leaving the closely monitored recovery area could potentially lead to respiratory complications. Our results do suggest that continuous paravertebral local anesthetic infusion could be a superior technique for this patient population. However, investigator bias can only be eliminated by well-designed clinical trials. Therefore, I suggest further randomized, double-blind, placebo-controlled studies of continuous thoracic paravertebral nerve blockade before promoting this technique as the analgesic gold standard in thoracoscopic surgery.
Duke University Medical Center, Durham, North Carolina. hill0012@mc.duke.edu
