Epidural anaesthesia is the most effective and well tolerated technique for pain relief during childbirth. However, some rare but worrisome mechanical complications such as impossibility of removal or breakage of the catheter may occur. The incidence of difficulty in epidural catheter withdrawal is estimated to be one in 20 000 to 30 000.1 We report here the case of an entrapped catheter in the epidural space in the course of obstetric analgesia. Its removal was possible after simple traction under general anaesthesia with muscular relaxation. This observation prompted us to review the major causes and means of prevention of these complications and we propose an algorithm to guide the management of mechanical complications of epidural catheters.
Written informed consent was obtained from the patient to publish this report.
We placed for labour analgesia an Arrow FlexTip Plus (Arrow International, Reading, Pennsylvania, USA) epidural catheter into the L2-L3 intervertebral space of a 32-year-old multiparous woman with a BMI of 24 kg m–2. The epidural anaesthesia was performed by an anaesthesiology resident, using a 17-gauge Tuohy needle with the patient in the sitting position. The catheter was positioned after a single attempt using the standard loss of resistance technique with 0.9% saline and the epidural space was located at a depth of 8.5 cm from the skin. The epidural catheter was inserted without difficulty up to the 20 cm mark, and the needle was removed. The catheter was left with the 15 cm mark at the skin. The patient had no paraesthesia during the procedure. The catheter was used successfully for analgesia during childbirth and the patient delivered uneventfully 3 h later. Two hours after delivery, the nurse called the resident because of resistance felt during traction, and the impossibility of removing the catheter. Despite further attempts by the resident and two senior anaesthesiologists with the patient in the lateral decubitus position in flexion and then in the sitting position, the catheter could not be removed. It was decided to wait 1 h after taping the catheter to the patient's back under gentle traction and try again. This manoeuvre was also unsuccessful, and the catheter remained stuck at the 15 cm mark at the skin. It was then decided to perform a lumbar computed tomography (CT) scan (Fig. 1). This showed that the catheter was in the L4-L5 anterior epidural space, with several loops behind the disc and lateralised on the left. There was no collection or haematoma detectable in epidural spaces. In addition, no sensory or motor neurological abnormalities were noted.
The therapeutic options were discussed, and surgical removal of the catheter was decided in agreement with the patient and the neurosurgery team.
The intervention was scheduled 2 days after placement of the epidural catheter. It was performed under general anaesthesia with succinylcholine. Prior to incision, the surgeon pulled on the catheter with the patient in the knee-chest position, which allowed it to be removed in its entirety without particular difficulty.
The subsequent postpartum course was uneventful, and no neurological sequelae developed.
The impossibility of removing an epidural catheter is a rare complication, with an estimated incidence of 0.0015%.2 This complication is often associated with the formation of loops or knots during catheter insertion into the epidural space or to aberrant catheter travel.
Several mechanisms can be advanced to explain the case reported here. The complication may have been caused by a descending and aberrant trajectory of the Tuohy needle during localisation of the epidural space. In fact, the initial approach was made at the L2-L3 level, but the lumbar CT scan revealed an oblique paramedian path with anterior epidural space involvement at the L4-L5 intervertebral space. This explains the identification of the epidural space at 8.5 cm in this nonobese patient. With a BMI of 24 kg m–2, the expected depth of the epidural space would be between 4 and 5 cm.3 The identification of the epidural space at such a depth should have been a warning sign leading the resident to seek advice from the senior anaesthesiologist before proceeding. In addition, in contrast to catheter insertion in a midline approach, a paramedian one may favour entrapment of the catheter by reaching the bellies of the semispinalis muscles wherein the muscle bulk is greatest.4 This may also have caused catheter retention in this patient who had strong dorsolumbar musculature.
Finally, an excessive length of catheter initially inserted in the needle (20 cm) and then left in the epidural space (6.5 cm) may have favoured the formation of loops. Indeed, it has been suggested that initial insertion of excessive amounts of catheter may lead to deviations in direction, coiling, kinking or doubling back. Also, the length of catheter left in the epidural space at the lumbar level should not be greater than 5 cm in order to minimise the likelihood of knotting and looping.2
A succession of different manoeuvres has been proposed to facilitate the difficult removal of an epidural catheter1,2,4,5 (Fig. 2). After the failures of these manoeuvres in our patient, we performed an imaging study as recommended. Indeed, the difficult removal and/or rupture of an epidural catheter during its installation or removal requires careful radiological investigation to locate the foreign body and clarify its position in relation to nerve structures.6 It has been suggested that CT scan is preferable to MRI, especially for sheared ferromagnetic catheters.4
The management of entrapped catheters or retained fragments after epidural anaesthesia has been discussed in several publications and is a subject of controversy.1,2,4 The major point of controversy is the approach to take with regard to the remaining fragment: surgical removal or leave in place, as the fragments are generally well tolerated if not located intrathecally, not around a nerve root and as long as there are no neurological signs or symptoms.4 In the case reported here, despite the fact that the CT scan showed that the catheter was located in the epidural space and that the patient had no neurological symptoms, we decided to remove it surgically. The reasons for our choice were the patient's refusal to keep a fragment in place and the relatively large size of the catheter fragment present in the epidural space, with a possible risk of a direct mass effect on neuronal tissue leading to neurological sequelae.4 The patient was informed of the increased risk of neurological damage from the surgery due to a risk of infection, fibrosis or mechanical neural irritation. She confirmed her preference for surgical removal.
Some authors have suggested that induction of general anaesthesia and injection of a short acting muscle relaxant might be a solution prior to surgery to remove the catheter.7 In fact, paralysis during induction of anaesthesia can make the muscles relaxed and the vertebral column loose enough to remove the catheter. This strategy was successful in the present case.
Mechanical complications of epidural catheters, such as impossible withdrawal or breakage, are rare but worrisome for the patient and the anaesthesiologist. The incident that occurred in our patient prompted us to review the literature regarding the main causes and mechanisms of these complications and their prevention, and to propose a management algorithm (Fig. 2).
Acknowledgements relating to this article
Assistance with the case report: the authors appreciate the suggestions and interest from Drs. Florain Deleu, Fadoua Aloussi, Laurent Sofiane Baccar and Professor Philippe Decq.
Financial support and sponsorship: none.
Conflicts of interest: none.
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