In Reply:-I thank Moore for his interest and comments on my recent correspondence [1]and article. [2]I believe we did indeed determine the optimal distance an epidural catheter should be threaded into the epidural space for the woman in labor receiving 13 ml of 0.25% bupivacaine. Moore is correct that the catheter must not only be placed in the epidural space, but must remain there for continued analgesia. This point was addressed in our study.
The primary purpose of our study was to determine the optimal distance a catheter should be threaded into the epidural space at the time of insertion that would reduce the incidence of incomplete analgesia for the woman in labor. We found (using multiorifice catheters and 0.25% bupivacaine), that women in whom catheters had been threaded 5 cm had a lower incidence of incomplete analgesia than women in whom catheters were threaded 3 or 7 cm. We then followed the patients throughout the course of their labor (as Moore suggested) to determine how many patients, once satisfactory analgesia had been achieved, would require replacement of their catheter. We found only one patient in the entire study (in the 3 cm group) who required catheter replacement.
I do not believe that obtaining a roentgenographic study, either at the time of catheter insertion or after delivery, would add to our clinical study. If the patient was comfortable throughout the course of her labor, x-ray findings would not have changed our conclusions. In addition, an x-ray might even confuse the clinical picture. Gielen et al., [3]in a roentgenographic study, found that only 10% of all epidural catheters were positioned in the midline, yet 95% of all the patients had a bilateral block.
In summary, I believe that Moore's concerns have been addressed in our study. All patients were evaluated for initial quality of analgesia and followed for subsequent failure. Obtaining an x-ray, although perhaps academically satisfying, would not have added to this clinical study-and may have confused the picture. I do, however, agree with Moore that our conclusions only pertain to the patient population studied (i.e., women in labor who received an epidural anesthetic with 0.25% bupivacaine via a multiorifice catheter.
Yaakov Beilin, M.D.
Assistant Professor of Anesthesiology
Mount Sinai School of Medicine
1 Gustave L. Levy Place, Box 1010; New York, New York 10029
(Accepted for publication December 12, 1996.)