We appreciate the correspondence from Drs. Hopf and Leischik elaborating on the difficulties of removing the Arrow (Reading, PA) FlexTip epidural catheter. In our patient, 1as in the first patient described by Drs. Hopf and Leischik, the catheter could not be removed even when the patient was in the position in which the catheter was placed originally. For the other cases they described, it seems that placing the patient in the original position resulted in easier removal of the catheter than while the patient was in any other position. This may imply that compressive forces that exist when the catheter is in place between bony structures may be minimized when the patient is returned to the original insertion position. It also implies that greater friction forces exist with this catheter than with other types of catheters.
As Keim 2noted, the FlexTip Plus is made from a very soft polyurethane material. When passed through the epidural needle, it is probable that little if any lateral force exists that would produce friction that could impair insertion, and the softness of the catheter may be a significant attribute. It is probable that considerable lateral force is applied to the catheter by tissue after the needle is withdrawn. One can speculate that the coefficient of friction may not correlate with the firmness of the catheter, and could potentially be greater with the Flex Tip catheter than with other types of catheters. This might be an important factor in the difficulty of removal. This seems to be an area that may prove to be a fruitful topic for further study. We agree with Drs. Hopf and Leischik that the difficulty of removal may be of considerable clinical importance and should result in appropriate labeling of the device.