Continuous peripheral nerve blocks are effective techniques to provide postoperative analgesia for patients undergoing surgery to the upper and lower extremities (1–3). However, the insertion of an indwelling catheter into a perineural sheath may be complicated by catheter kinking and knotting, resulting in breakage during removal. Although there are several published reports of neuraxial catheter knots, as well as techniques to facilitate removal of these entrapped catheters (4–8), there are few data regarding the management of knotted (9–11) or retained (12,13) peripheral nerve catheters. We present a case of an entrapped fascia iliaca catheter secondary to a true knot. Successful removal was accomplished by shifting the patient’s position to decrease tension on the catheter.
A 64-yr-old woman with bilateral coxarthrosis presented for right-sided total hip arthroplasty. Her preoperative medications included a fentanyl (Duragesic®-50) patch. A combined general/regional (continuous fascia iliaca block) anesthetic was planned. The patient was taken to the operating room and placed in the supine position. The inguinal ligament was identified by palpation of the anterior superior iliac spine and the pubic tubercle and was divided into thirds. A mark was made 1 cm inferior to the junction of the middle and lateral thirds, and an 18-gauge, 3.5-in. Hustead needle was introduced and placed behind the fascia iliaca via the “double pop” technique. A standard 20-gauge, nylon, closed-end epidural catheter (Portex, Inc., Keene, NH) was advanced 10 cm past the tip of the needle. An initial bolus of 30 mL of 0.5% bupivacaine with epinephrine 1:200,000 and 100 μg of clonidine was injected, and general anesthesia was induced. An infusion of 0.1% bupivacaine at 20 mL/h was initiated upon the patient’s arrival in the recovery room. It was anticipated that the fascia iliaca infusion would continue for 48 h.
The patient had adequate incisional pain control, complaining chiefly of discomfort in the nonoperative hip in the immediate postoperative period. Approximately 48 h after surgery, catheter removal was attempted with the patient in the supine position. The catheter was at the 12-cm mark at the skin and retracted easily to the 8-cm mark, at which point a significant amount of resistance was encountered. The patient was placed in a partial sitting position with 50° of hip flexion, and gentle traction was applied, but the catheter began to attenuate such that the 1-cm markings were 1.5–2 cm apart. The patient was placed in additional flexion, with an angle of approximately 90° at the catheter insertion site. Application of firm, steady traction resulted in successful catheter removal. The catheter was intact. However, a knot was situated 2 cm from the tip (Fig. 1). There were no neurologic sequelae, and the patient recovered uneventfully. Six weeks later, she underwent hip replacement on the contralateral side with a similar anesthetic technique; the fascia iliaca catheter was removed without difficulty.
Fascia iliaca blockade was first described in 1989 by Dalens et al. (14). The technique is a variant of the three-in-one block originally described by Winnie et al. (15) and is often referred to as a “modified femoral three-in-one block” (1). Continuous fascia iliaca and three-in-one blocks provide effective postoperative analgesia after lower extremity operations, including hip and knee arthroplasty (1–3). Complete blockade of the lumbar plexus is more likely if the catheter is advanced 15–20 cm proximally and if the tip is located superior to the sacroiliac joint within the psoas sheath (1,2). However, few catheters (23%–40%) attain the ideal proximal location; most remain coiled in the femoral head region, near the site of insertion. Importantly, ease of catheter advancement is not indicative of final catheter tip location (1,2).
There are few data on the optimal length of insertion of fascia iliaca and other peripheral nerve catheters. The improved success with proximal catheter tip position supports insertion of fascia iliaca catheters to 15–20 cm, but this must be balanced with the propensity for catheter coiling (and, theoretically, kinking and knotting). This is in contrast to epidural catheter placement, for which it has been suggested that the farther an epidural catheter is advanced past the needle tip, the more likely it is to loop, knot, and malfunction (16,17). For example, a catheter length ranging from 1 to 5 cm past the tip of the needle has been proposed for optimal epidural insertion, although there is no consensus (4,16).
Several techniques have been described to facilitate removal of an entrapped epidural catheter. In general, the approach is to minimize bony structure/soft tissue obstruction to reduce the force required to withdraw the catheter, thereby decreasing the likelihood of catheter breakage. Previous clinical investigations have demonstrated that the flexed position is superior for removal of an entrapped epidural catheter and that 2.5 times as much force is required to remove an epidural catheter in the flexed sitting compared with the flexed lateral position (5,7,18,19). The principle of “placing the patient in the position in which the catheter was inserted” when resistance is encountered during catheter removal is in part derived from these cases and investigations. However, it should be considered that the flexed lateral position is not only the position in which neuraxial catheters are placed, but also the position in which bony and soft tissue obstructions are minimized. Other maneuvers include applying firm, steady pressure, pulling the catheter taut (and taping it to the patient’s back or securing it with a tongue depressor to provide gentle traction) and attempting removal hours later, intervening radiologically with passage of a guidewire, and inducing general anesthesia with muscle relaxation (5,18,19). Surgical removal is typically reserved for retrieval of neuraxial catheter fragments that are ferromagnetic, within the intrathecal space, or chronically associated with symptoms of nerve irritation (4,7,20).
Application of these principles may be helpful in the removal of an entrapped peripheral catheter. Peripheral catheters are typically placed with the extremity extended to facilitate identification of superficial landmarks and associated vascular structures. Although facilitating catheter placement, this positioning stretches soft tissue—including sheath, muscle, and fascia—and theoretically increases resistance to catheter extraction. Conversely, catheter removal should be enhanced by release of soft tissue tension/resistance, which may be in a position other than that of catheter placement. For example, during continuous fascia iliaca block, the catheter has traversed the fascia lata and the fascia iliaca. Placing the patient in the supine position conceptually “tightens” these fascial planes and will make removal of a kinked or knotted catheter more difficult. Flexion of the ipsilateral hip conceptually “loosens” these fascial planes and facilitates entrapped catheter removal. In the present case, hip flexion of approximately 90° was needed to allow catheter removal. Placement of the patient in a lateral position may have also theoretically decreased tissue resistance, but this was not necessary or attempted. We have subsequently encountered one additional entrapped (kinked) fascia iliaca catheter, which was successfully removed by flexing the hip to approximately 90° and applying firm, steady traction. As with neuraxial catheters, surgical or fluoroscopically guided retrieval of peripheral nerve catheters may be necessary if symptoms of neural irritation are encountered during attempted removal.
In summary, the optimal distance a fascia iliaca catheter is advanced to achieve successful modified three-in-one blockade is unknown. Although proximal placement of the catheter tip is associated with an increased success rate and improved clinical outcome, the longer the length of catheter threaded beyond the tip of the needle, the higher the likelihood of looping, kinking, and knotting. Furthermore, catheter-related complications will occur occasionally regardless of the catheter length inserted. We present successful removal of a knotted fascia iliaca catheter by placing the patient in hip flexion (which is in opposition to the position of catheter placement). Thus, when entrapped peripheral catheters are encountered, successful removal is based on the same principles as those of entrapped neuraxial catheters, with emphasis on placing the patient in a position that minimizes tension on bony structures and soft tissues. In the case of fascia iliaca catheter entrapment, flexion of the ipsilateral hip joint greatly improves the chances of avoiding operative intervention or retained catheter fragments.
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