In Reply:--The management of epidural catheters for laboring patients can be quite labor intensive: Michael et al reported a 33% incidence of inadequate analgesia after insertion of uniport epidural catheters. Our study was designed to determine which insertion length minimizes insertion-related complications and the effectiveness of epidural catheter manipulation when associated with intravenous cannulation or unilateral sensory analgesia after insertion. In practical terms, can the time spent inserting and manipulating uniport epidural catheters be minimized?
We concluded that uniport epidural catheters could be inserted either 2 or 6 cm within the epidural space based on the anticipated duration of labor. Beilin argues that he cannot predict obstetric outcome and therefore would have concluded that all epidural catheters should be inserted 6 cm within the epidural space. I would argue that, although one cannot precisely predict the duration of labor for a given patient, the multiparous patient presenting in active-phase labor with a history of previous uncomplicated vaginal deliveries, on average, would deliver more quickly than the prima gravida or the multiparous patient presenting in latent-phase labor. In our study, we found that inserting uniport epidural catheters 2 cm minimizes insertion-related complications ; however, as Beilin notes, epidural catheters inserted 2 cm within the epidural space are more likely to subsequently dislodge. Although true, catheter dislodgment occurred in only 16 of 200 epidural catheters inserted 2 cm within the epidural space and dislodged an average 6.5 h after insertion, significantly longer than the reported mean 3.2-h duration of active-phase labor in the multiparous patient. Therefore, based on these findings and despite Beilin's argument, I recommend inserting uniport epidural catheters 2 cm in the multiparous patient presenting in active-phase labor. In all other patients, I would insert epidural catheters 6 cm within the epidural space. In addition, as Beilin suggests, I would consider a combined technique in these patients but would insert the uniport epidural catheter 2 cm within the epidural space after the subarachnoid injection.
Beilin questions our conclusion that epidural catheter manipulation may be more time-efficient than epidural catheter replacement because 65 min was required to achieve patient comfort in one patient in whom the epidural catheter was inserted 8 cm within the epidural space. Beilin also suggests that we should have either administered additional local anesthetic before catheter manipulation or automatically replaced epidural catheters associated with inadequate analgesia. However, as previously stated, one purpose of our study was to determine the effectiveness of catheter manipulation. Because catheter manipulation was effective in 91% of epidural catheters inserted > 2 cm associated with unilateral analgesia and 50% of catheters inserted intravenously functioned well after catheter manipulation, I believe our recommendations regarding catheter manipulation are justified. I agree that 65 min to achieve patient comfort is an excessive amount of time. However, 783 other patients became comfortable in < 65 min. In addition, clinical practice is not dictated by strict research protocol, and our clinical practice uses earlier, more aggressive catheter manipulation. Finally, regarding administration of additional local anesthetic before catheter manipulation, we know of no series that has randomly investigated the efficacy of administering additional local anesthetic in the presence of unilateral analgesia. However, we have observed that this practice, if ineffective, will delay achieving patient comfort that Beilin and we oppose. I believe the findings of our study can be applied in clinical practice. Currently, I insert epidural catheters 6 cm within the epidural space. If analgesia is inadequate 10–15 min after local anesthetic administration, I withdraw the catheter 3–4 cm and administer local additional anesthetic. If the patient is not comfortable within 10 min after additional drug administration, the epidural catheter is removed and replaced. As a result, the patient is either comfortable or the epidural catheter is replaced within 20 min of initial placement. This practice, I would argue, is expedient for the anesthesiologist and the patient.
Robert D'Angelo, M.D., Assistant Professor of Anesthesiology, Section of Obstetric Anesthesia, Department of Anesthesia, Wake Forest University Medical Center, Bowman Gray School of Medicine, Winston-Salem, North Carolina 27157, Electronic mail: firstname.lastname@example.org.