Abstract

When administering postoperative acute pain services, particularly regarding patient- controlled epidural analgesia, difficulties may occasionally be encountered during removal of the epidural catheter. In this report, we present an instance of difficult removal of epidural catheter in a female patient undergoing open reduction and internal fixation of the femoral neck with patient-controlled epidural analgesia as the means of postoperative pain control. The patient had satisfactory analgesia for 3 days; however, during the removal of the epidural catheter, difficulties were encountered and epidurogram revealed that the epidural catheter had become anchored in the anterior epidural space without kinking or knotting. Subsequently, the patient was requested to lie prone on the surgical table with a pillow placed beneath her lower abdomen and catheter removal was tried again. Fortunately, the epidural catheter was removed easily without the need for a guided stylet. We believe that the cause of the difficult removal of the epidural catheter in this case might have resulted from an unusual and unwanted deeper anchorage of the catheter along the anterior epidural space during placement. We also include some discussion on the management of problematic removal.

Keywords

analgesia; epidural; catheters; indwelling; contrast media; epidural space: anterior; fluorosco; pyprone position;

1. Introduction

Patient-controlled  epidural  analgesia  (PCEA)  can  provide excellent pain relief after truncal surgery. However, difficulty in removing the epidural cath-eter   may   occasionally   arise.   Management   of   epidural  catheter  extraction  has  been  reported,¹ but  there  are  no  clear  management  guidelines.

A  common  manipulation  is  to  request  the  patient  to assume the same position as when the catheter was  inserted.²  A  continuous  and  steady  force  is  recommended  when  the  catheter  is  being  re-moved.  If  this  does  not  work,  we  must  consider  the  possible  reasons  for  why  the  catheter  cannot  be removed, such as knotting and kinking. Knotting is  the  most  common  cause  of  difficult  removal, and if present, its whereabouts may be determined by radiological imaging.³

To our knowledge, this report is the first to de-scribe difficult removal of epidural catheter due to incidental placement of the catheter in the anterior epidural space. After several unsuccessful attempts to remove the catheter, fluoroscopy was employed to determine the cause. Before resorting to a more invasive method, we tried again to retrieve the cath-eter with the patient in the prone position. Fortu-nately,  the  catheter  was  successfully  removed  on  this attempt with no adverse sequelae.

2. Case Report

A 32-year-old woman (weight, 72 kg; height, 156 cm) with  no  history  of  systemic  disease  was  admitted  to our hospital for orthopedic surgery due to right femoral neck fracture. To provide adequate post-operative  analgesia  for  facilitating  postoperative  recovery, an epidural catheter was inserted for post-operative pain control before spinal anesthesia. An 18-gauge Tuohy needle was inserted via the para-median approach at L3−L4 vertebral interspace and the epidural space was identified by using the loss-of-resistance to air technique. An 18-gauge Portex® epidural catheter (Smiths Medical International Ltd, Kent, UK) was then inserted and advanced 7.0 cm into the epidural space with the 14-cm mark at the aperture of the skin without any difficulty. An epi-dural test dose of 3 mL of 2% lidocaine with 1:200,000 epinephrine indicated positively that the epidural catheter was neither intrathecally nor intravascu-larly placed. The patient tolerated the procedure well and had a smooth postoperative recovery with satisfactory pain control.

Three days after the operation, when it was time for the catheter to be removed, the anesthesia res-ident encountered difficulty in removing the cath-eter  and  had  two  failed  attempts.  The  attending  anesthesiologist who came to help the resident also encountered  difficulty,  even  with  the  patient  as-suming either the sitting position with flexed back or the lateral decubitus flexion position. After ex-plaining the situation to the patient and her family, and discussing the options with them, the patient was sent to the operating room for an epidurogram in order to discover the cause of difficult removal.

The patient lay on the surgical table in the prone position  with  a  pillow  placed  beneath  her  lower  abdomen. The epidurogram showed that the cath-eter was partially located in the anterior epidural space  (Figure  1),  and  had  not  knotted,  kinked  or  broken (Figures 1−3). The path of the epidural cath-eter, as traced, started from the left border of the L3  superior  endplate  of  the  vertebral  body,  then ran close to the inferior border of the pedicle, and finally entered the anterior epidural space proba-bly through the left L2 foraminal space (Figure 1).

We made another attempt to remove the cath-eter, and fortunately, the catheter was easily ex-tracted on this last attempt. The catheter was largely intact,  but  a  deformed  section  was  noted  around  the  entrapped  point  of  the  catheter.  The  patient  was discharged 2 days later without any neurologi-cal sequelae.

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Figure 1 Epidurogram, lateral view, shows catheter placement in the anterior epidural space.

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Figure 2 (A) Preoperative X-ray shows no significant findings except for lumbar sacralization. Epidurogram shows no knotting or shearing: (B) anteroposterior view; (C) potential pathway of the epidural catheter (represented by the red dotted line).

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Figure 3 The removed epidural catheter shows no knotting or breaking, but a deformed section is noted at the entrapped point of the catheter (arrow).

3. Discussion

Difficult removal of epidural catheters occasionally occurs, and several maneuvers have been recom-mended:⁴⁻⁷  (1)  use  slow,  continuous  and  steady  pressure on the catheter to avoid catheter break-age;  (2)  reapply  force  and  traction  several  hours  later; (3) have the patient adopt the same position as  when  the  catheter  was  inserted;  (4)  have  the  patient  adopt  the  lateral  decubitus  position  (as  greater  force  is  required  to  remove  the  epidural  catheter in the flexed sitting position than in the lateral position); (5) attempt removal after injec-tion of normal saline through the catheter, which may also assist in determining whether the catheter is knotted.

There  are  several  causes  of  problematic  epi-dural catheter removal, such as catheter breakage or knotting.^8,9 In this instance, the patient experi-enced  satisfactory  postoperative  analgesia  for  3  days. To evaluate the difficult removal of the cath-eter,  we  administered  normal  saline  through  the  catheter to exclude the possibility of catheter knot-ting, because the catheter had been inserted more than 5 cm into the epidural space.¹⁰ Catheter knot-ting is a typical but rare complication of epidural anesthesia/analgesia, with an approximate incidence of 0.0015%.¹¹ The catheter being threaded into the epidural  space  too  deeply  is  a  risk  factor  for  this  complication.12 In order to identify other possible etiologies of entrapment and location of epidural catheter, fluoroscopy may be required.¹³ The patient lies on the surgical table in the prone position on a pillow for taking the epidurogram. In our patient, after  injecting  3  mL  of  contrast  dye  (Isovist-300),  the epidurogram confirmed that the catheter was inserted from the L3/4 interspace and had entered the anterior epidural space without knotting, shear-ing or other abnormal deformities. Then we tried to remove the catheter one last time; surprisingly, the catheter was successfully removed. In addition to the maneuvers described above, the prone position was recommended in one article.¹⁴ We believe that the  catheter  being  anchored  in  the  anterior  epi-dural space was the reason for its difficult removal in our patient. There is no report in the literature that explores the incidence of catheter anchorage in the anterior epidural space after it has been placed via the paramedian approach, and its potential dif-ficult removal. The primary cause of the catheter ending  up  in  the  anterior  epidural  space  may  be  related to the initial needle insertion spot, which was 3 cm lower from the L3/4 vertebrae interspace, the needle inserting angle, which is more acute in the paramedian approach, and the direction of nee-dle insertion. From the anatomic perspective, the anterior epidural space is narrower than the pos-terior  epidural  space.  The  occurrence  of  directly  placing an epidural catheter into the anterior space is very rare. Additional reasons for difficult catheter removal  in  our  patient  include  the  deeper  place-ment of the catheter and the fact that the patient was obese (body mass index, 29.6 kg/m²).¹⁵

In this case, we were able to remove the epidural catheter  only  when  the  patient  was  in  the  prone  position  with  a  pillow  placed  beneath  the  lower  abdomen.  The  possible  reason  for  successful  ex-traction in this obese patient is that as the pillow pressed against the abdomen, the back took on a more flexed angle. The contrast medium that was injected might also have acted as a lubricant and reshaped the catheter for easier removal.

In summary, gentle traction of the catheter with a constant force and with the patient lying in the prone position on a pillow is another feasible strat-egy that is worth trying when difficulty in epidural catheter removal is encountered. Such a modality can ease muscle relaxation and can facilitate cath-eter removal.