Blocked Epidural Catheter; its prevention and management

Introduction: Epidural anaesthesia is a central neuraxial block technique

with many applications. It is a popular and versatile anaesthetic technique

which can be used as an anaesthetic, analgesic adjuvant to general

anaesthesia, and for postoperative analgesia in procedures involving the

lower limbs, perineum, pelvis, abdomen and thorax. Both single injection

and catheter techniques can be used. Epidural catheter is introduced in

epidural space through epidural needle except when surgeon puts it in

epidural space during spinal surgery for postoperative analgesia. The

catheter works as a conduit to deliver anaesthetic/analgesic drugs at target

(epidural space) during intraoperative as well as postoperative period.

Epidural catheter helps to maximize the potential of epidural

anaesthesia in intraoperative as well as in postoperative period. However,

blocking of epidural catheter is a technical snag which results in partial or

complete failure of epidural technique. The potential causes, contributing

factors, and proposed mechanisms of blocked epidural catheter may be

grouped into four major categories: anatomic factors; technique,

methodology and equipment; patient-related factors; and technical skills, or

performance factors

In present article the various cause of epidural catheter blockade, its

prevention and management to handle the situation once it has occurred are

discussed.

How epidural catheter get Blocked: Epidural catheter is a thin, hollow

tubular structure of polymers opened at both the ends. The terminal

(epidural) end may have either single or multiple openings depending upon

type of catheter; single port or multiport. The lumen of catheter is very

small and may get obstruct either due to blood-clot or tissue debris in the

lumen or due to kinking and knotting. Catheter migration may result in or

out ward movement of catheter which can result in forward movement and

kinking or coiling in subcutaneous area. Improper fixation of catheter may

also be responsible for blocked epidural catheter by helping in migration.

The obstruction may be due to manufacturing defect in catheter

resulting in absence of terminal openings. Faulty storage technique of

catheters also influences this complication of catheter block as extreme

ambient temperature may cause brittleness in the catheter material. This may

lead to cracks or breakage of catheter and obstruction of catheter lumen.

At times the cause of obstruction is within ‘catheter connector

assembly’ through which anaesthetic/analgesic drugs are injected. The

causes may be improper attachment (insertion of catheter in assembly) or

manufacturing defect leading to failure of assembly to function properly.

Blocked epidural catheter; historical perspective: For many years, the

catheters used for epidural anaesthesia were simply "plain tubes”. The cut

end of such catheter was relatively traumatic to the tissues and more likely to

penetrate vessels and get blocked by blood clot. Lee's catheter1 was one of

the first with a smooth non-patent tip and a single lateral eye. Over the years

more lateral eyes were incorporated in catheter-design thinking; lesser

possibility of kinking and block.2, 3Today, the two types of epidural catheter

most commonly used world-wide are the terminal eye variant and the one

with three lateral eyes. There is no substantial proof of superiority of one

design over other (terminal hole vs. multi lateral eyed catheters).4 However,

in one series, 8% of the terminal eye catheters had to be replaced compared

to 2% of the lateral eye catheters.2

Catheter migration: Migration has been shown to be relatively

common, occurring in approximately one-third of the patients in one study.5

There were significant positive correlations between outward migration and

weight, body mass index, and depth of the epidural space.5 Conventional

dressings do not always prevent epidural catheter movement into or out of

the epidural space, lack of transparency also prevents observation of the

catheter and the puncture site. The "Op-site" surgical dressing is an adherent

membrane which has prevented epidural catheter migration in 200

obstetrical patients.6 However, migration of an epidural catheter related to

flexion and extension of the Spine can result in subcutaneous coiling and

blockade of epidural catheter. It has been noticed that even with the

application of a firm adhesive dressing anchoring the catheter to the skin, the

catheter can move and coil within the patient.7

Several innovative techniques have been used to prevent catheter

migration and proved superior to the conventional dressing; significant

prevention of catheter migration with “Lockit” than with conventional

dressing (p<.001).8 Tunneling of epidural catheter has also been tried to

prevent migration.9 However, till today there is no such ideal device which

can prevent migration in all cases moreover, they are not always superior to

transparent dressings.10

Blood in epidural catheter: Clotted blood in epidural catheter is an

important and common cause of epidural catheter blockade. Blood in

epidural catheter can be due to blood vessel trauma while placing the

catheter, accidental intravenous placement or migration and/or a deranged

coagulation profile. The incidence of unintended intravascular

entry by epidural catheters is estimated to be between 4.9% and 7% in the

obstetrical population11 however, the contribution of blood-clot in overall

incidence of blockade of epidural catheter is not known.

There are various factors responsible for vascular injury by epidural

catheter leading to blocked catheter. Patient with inferior vena cava (IVC)

obstruction have dilated epidural veins which may sustain injury at the time

of epidural catheter placement or later, resulting in accidental intravascular

placement or migration of the catheter.12

Prevention & Management: When blood is seen in catheter, withdrawing

the epidural catheter 1 or 2 cm may be helpful in some cases11 Replacing the

catheter may result in repeated intravascular cannulation13 therefore

strategies to avoid epidural vein cannulation during the initial epidural

catheter placement should be used to avoid complication of blood in

catheter. The risk of intravascular placement of a lumbar epidural catheter

may be reduced with the lateral patient position, fluid pre-distension, a

single orifice catheter, a wire-embedded polyurethane epidural catheter and

limiting the depth of catheter insertion to 6 cm or less.14 If obstruction is due

to suspected blood clot; insertion of new stylet of epidural catheter can be

tried to dislodge the clot.15 We have tried and overcome the problem of

catheter block due to blood clot by using 2ml saline filled syringe. However,

it is not recommended because high pressure generated by small syringe

may be harmful to micro filter and tissues.

Kinking & knotting of epidural catheter: Kinking of an epidural catheter

is a rare complication of epidural analgesia. Kinking of an epidural catheter

may occur at any point between the skin and the epidural space.16 Occlusion

of catheter lumen may occur due to acute bending which is obstructing the

lumen of the catheter17 or may be due to a laminar “pincer,” or knotting of

the catheter.18 Kinking of epidural catheter outside the epidural space and

also in the subcutaneous tissue which became blocked after initial successful

functioning, has been reported by several authors.19,20 There are many case

reports in literature regarding such complications involved single knot near

the distal tip of the catheter21,22,23, 24,25 ,26 or double knot after a combined

spinal-epidural anesthesia27 and thoracic epidural anaesthesia.28Definitive

etiology of catheter kinking is not known however, an epidural catheter may

be deflected by anatomical obstacles and can curl back on itself. [Figure-1]

The conclusion of some reports is that insertion of excessive amounts of

catheter into the epidural space is a causative factor in knot formation.27, 29, 30

Prevention: Prevention is the only key factor to avoid such complications

because once knot is formed it’s impossible to deliver epidural drug through

that catheter. Moreover, this may further complicate the situation by

difficulty in removal of catheter. Undue force should be avoided during

catheter insertion to avoid coiling and kinking which may result in knot

formation. Several sources have suggested that advancing the catheter a

certain distance in the epidural space increases the incidence of epidural

catheter knotting. Although, ideal length of catheter to be inserted in

epidural space to avoid kinking/knotting is not known Gozal et al31

recommended the catheter be threaded less than 3 to 4 cm beyond the needle

tip. Browne and Politi32 recommended threading the catheter less than 5 cm.

Muneyuki et al33 reported threading thoracic epidural catheters up to

10 cm without catheter curling. However, some authors have recommended

the insertion of no more than 4 cm of catheter into the epidural space and

some others no more than 5 cm22, 23, 30

Management of knotted epidural catheter: Once knotting is suspected and

injection through catheter is not possible, catheter has to be removed.

Multiple reports show that they can often be removed intact with

traction.21,23,,24,25,26,29 However, catheter breakage is a reported risk potentially

entailing extensive surgical exploration.34 Renehan et al26  have suggested an

approach to the management of a trapped lumbar epidural catheter:

1. Gentle traction on the catheter with the patient in various positions

and in various degrees of lumbar flexion and extension. There is some

evidence that the force required for catheter removal is reduced when

the patient is in the lateral decubitus position

2. Determination of the patency of the catheter by attempting to inject

sterile, preservative-free normal saline through the catheter

3. Radiological imaging with radiopaque dye if the catheter is patent or

with a guide wire if the catheter is occluded

4. Radiological evaluation on the position relative to the epidural space

and orientation of a knot to guide the decision on whether consultation

with a surgical specialty is required

If difficulty is anticipated or faced during catheter removal, visualization can

be facilitated with computer tomography (CT) and magnetic resonance

impedance (MRI).35, 36  

Catheter malfunction and catheter defects: The use of plastic catheters

was first described by Flowers et al. in 1949 the first polymer (plastic) was

polyethylene. It was soon replaced by polyvinyl chloride because of its low

melting point, which, similar to the lacquered silk catheter, made it prone to

swelling and deformity with sterilization. More recent polymers are nylon,

Teflon, polyurethane and silicone which are resistant to deform on routine

use and storage.

Although the rate of isolated manufacture catheter defects is

unknown, it seems to be relatively low. Manufacturing defects in terminal

holes may result in either absence of hole(s),37, 38 or blocked catheter eyes

(mostly terminal eye catheters)2 Manufacturing defects may result in only

narrowing of lumen39 or with absence of terminal eyes which leads to block

in epidural catheter.40 Quality of catheter material may also responsible for

easy kinking and catheter block.41 To avoid this complication a simple pre-

insertion test is helpful to detect catheter with faulty material.42 Goyal M,

43has suggested using reinforced epidural catheter to avoid the problem of

kinking.

Manufacturing defects in Connector assembly: There are several reports

in literature where epidural catheter failed to deliver drugs either in the

beginning while test dose was given or at the subsequent dosing. Other than

the defects in catheter itself 44 (defects in lateral eyes/terminal opening or

catheter tube), connector assembly may be responsible for such ‘blocked

epidural catheter’ incidences.45 Nagi H46 reported an incidence of blocked

epidural catheter where block was in connector assembly due to manufacture

error during the injection moulding process. There are reported incidences

of blocked epidural catheter because the catheter was not inserted into the

connector to its full length.47, 48, 49

Prevention & Management: It’s desirable to detect manufacturing defect

before insertion of epidural catheter by visual inspection and patency testing

of connector assembly and then of catheter by connecting it to connector.

This exercise will easily detect the site of blockade.50Whether air or saline is

ideal for patency testing is not known. However, one report suggested that

defects which are missed by testing with air could have been prevented by

saline.47

Conclusion: Difficult or impossible injection via the epidural catheter can

be a result of several causes, resulting in mechanical obstruction of the

epidural catheter at various levels. Apart from accidental kinking, knotting,

axial torsion, and malposition of the catheter, occasional manufacturing

defects of the catheter (e.g., catheter without terminal helical “eyes”) can

lead to this problem. Many of such problems can simply be avoided by

patency test before insertion of catheter. If nothing works it’s advisable to

reinsert the epidural catheter taking precaution by patency testing of catheter

and connector assembly to avoid such complications. Proper fixation is in

integral exercise for proper functioning of catheter which should be done

preferably with transparent dressing and should be followed by regular

check for in-and- out movement of catheter. This exercise will give early

warning to initiate necessary action.

References:

1. Lee JA. A new catheter for continuous extradural analgesia.

Anaesthesia 1962;17:248-250.

2. Collier CB, Gatt SP. Epidural catheters for obstetrics; terminal hole or

lateral eyes. Regional Anesthesia 1994;19:378-385.

3. Skinner BS. A new epidural cannula. Canadian Anaesthetists' Society

Journal 1966; 13:622-623.

4. Michael S, Richmond MN, Birks RJS. A comparison between open-

end (single hole) and closed-end (three lateral holes) epidural

catheters. Anaesthesia 1989; 44:578-580.

5. Bishton IM, Martin PH, Vernon JM, Liu WH. Factors influencing

epidural catheter migration. Anaesthesia 1992;47:610-2.

6. Duffy B L. Securing epidural catheters. Canadian Journal of

Anesthesia 1982; 29:636-637.

7. Dunbar S. Migration of an Epidural Catheter Related to Flexion and

Extension of the Spine. Anesth Analg 1993; 76: 906.

8. Clark MX, O'Hare K, Gorringe J, Oh T. The effect of the Lockit

epidural catheter clamp on epidural migration: a controlled trial.

Anaesthesia 2001; 56:865-70.

9. Chadwick VL, Jones M, Poulton B, Fleming BG. Epidural catheter

migration: a comparison of tunneling against a new technique of

catheter fixation. Anaesth Intensive Care 2003; 31:518-22.

10.Burns SM, Cowa CM, Barclay PM, Wilkes RG. Intrapartum

epidural catheter migration: a comparative study of three dressing

applications. Br J Anaesth. 2001; 86:565-7.

11.Pan PH, Bogard TD, Owen MD. Incidence and characteristics of

failures in obstetric neuraxial analgesia and anesthesia: a retrospective

analysis of 19,259 deliveries. Int J Obstet Anesth 2004; 13:227–233.

12.Kiran S, Taneja R. An unusual cause of clotted blood in epidural

catheter. S Afr J Anaesthesiol Analg 2010; 16:85-86.

13.Norris MC, Fogel ST, Dalman H, Borrenpohl S, Hoppe W, RileyA.

Labor epidural analgesia without an intravascular “test dose”.

Anesthesiology 1998; 88:1495–501. 

14.Mhyre JM, Greenfield M LVH, Tsen LC, Polley LS. Systematic

Review of Randomized Controlled Trials That Evaluate Strategies to

Avoid Epidural Vein Cannulation during Obstetric Epidural Catheter

Placement. Anesth Analg 2009; 108:1232–42.

15.Cohen S, Amar D. A simple solution to blood clot obstruction of

epidural catheter during labour. Can J Anaesth 1990; 37: 143-4.

16.Scawn NDA, Pennefather SH. More problems with clamping epidural

catheters. Anaesthesia 2000; 55:304.

17.Bajaj P, Raiger L, Raman V. Kinking of epidural catheter -a case

report. Indian J Anaesth 2003; 47:53-54.

18.Bromage PR. Epidural analgesia in obstetrics Philadelphia: WB

Saunders; 1978. p. 558-9.

19.Scawn NDA, Pennefather SH: More problems with clamping epidural

catheters. Anaesthesia 2000; 55: 304.

20.Gough J.D., Johnston K.R. and Harmer M.: Kinking of epidural

catheter. Anaesthesia 1986; 41: 1060.

21.Garca-Saura PL, Castilla-Peinado G, Parras-Maldonado MT. True

knot at the distal end of a catheter after insertion for obstetric epidural

analgesia. Rev Esp Anestesiol Reanim 2008; 55:256–257.

22.Arnaoutoglou HM, Tzimas PG, Papadopoulos GS. Knotting of an

epidural catheter: a rare complication. Acta Anaesthesiol

Belg 2007;58:55–57.

23.Brichant JF, Bonhomme V, Hans P. On knots in epidural catheters: a

case report and a review of the literature. Int J Obstet Anesth 2006;

15:159–162. 

24.Karraz M. Difficulty of withdrawing epidural catheter due to a

knot. Ann Fr Anesth Reanim 2002; 21:825–826. 

25.Macfarlane J, Paech MJ. Another knotted epidural catheter. Anaesth

Intensive Care 2002; 30:240–243. 

26.Renehan EM, Peterson RA, Penning JP, Rosaeg OP, Chow D.

Visualization of a looped and knotted epidural catheter with a

guidewire. Can J Anaesth 2000; 47:329–333.

27.Gabopoulou Z, Mavrommati P, Chatzieleftheriou A, Vrettou V,

Konstandinidou M, Velmachou K. Epidural catheter entrapment

caused by a double knot after combined spinal-epidural

anesthesia. Reg Anesth Pain Med 2005; 30:588–589. 

28.Hsin ST, Chang FC, Tsou MY. Inadvertent knotting of a thoracic

epidural catheter. Acta Anaesthesiol Scand 2001; 45:255–257. 

29.Ortez de Landázuri PJ, Boada PS, Ferrer GC, Puig BR, Sánchez HA,

Rull BM. Spontaneous kinking of an epidural catheter. Rev Esp

Anestesiol Reanim 2005; 52:121–122. 

30.Angle PJ, Hussain K, Morgan A. High quality labour analgesia using

small gauge epidural needles and catheters. Can J Anaesth. 2006;

53:263–267. 

31.Gozal D, Gozal Y, Beilin B: Removal of knotted epidural catheters.

Reg Anesth 1996; 21:71-73.

32.Browne RA, Politi VL: Knotting of an epidural catheter: a case report.

Can Anaesth Soc J 1979; 26:142-144.

33.Muneyuki M, Shirai K, Inamoto A: Roentgenographic analysis of the

positions of catheters in the epidural space. Anesthesiology 1970;

33:19-24.

34.Sakuma N, Hori M, Suzuki H. A sheared off and sequestered epidural

catheter: a case report. Masui 2004;53:198–200. 

35.Dam-Hieu P, Rodriguez V, De Cazes Y, Quinio B. Computed

tomography images of entrapped epidural catheter. Reg Anesth Pain

Med 2002;27:517–519. 

36.Aslanidis T, Fileli A, Pyrgos P. Management and visualization of a

kinked epidural catheter. Hippokratia 2010; 14: 294–296.

37.Soliveres J, Balaguer J, Solaz C, Estruch M, Sanchez J, Abreu T.

Epidural Catheters Without Holes. Reg Anesth Pain Med. 2008;

33:573–575.

38.Abouleish E. Pain Control. In: AbouleishE, editors. Obstetrics

Philadelphia: JB Lippincott; 1977. p. 260-304.

39.Tsai YS, Tseng CC, Su HP, Che PC. A rare case of epidural catheter

luminal obstruction. Available at http://www.thefreelibrary.com

visited on 14.8.11

40.K. Toker, Y. Gurkan, M. Keser. A Faulty Epidural Catheter. Anesth

Analg 2002;94:1371–72.

41.Roddin MJ, Dancey FML. Kinking of epidural catheters Anaesthesia

2000; 55: 831.

42.Beamer J. A simple method for testing for the kinking epidural

catheter. Anaesthesia 2000;55:1233-34.

43.M. Goyal. Reinforced epidural catheters. Anaesthesia 2001;56:94-95.

44.Gupta SL, Mishra SK, Elakkumanan LB, Sudeep K. Multiport

epidural catheter without port and incomplete marking. Indian J

Anaesth 2010 ; 54: 359–360.

45.Harada C, Sakuragi T, Katori K, Higa K. Impossibility of injection

through an epidural catheter caused by an incorrect connection of

catheter and connector. European Journal of Anaesthesiology2003; 20:

585-586.

46.Nagi H. Blocked epidural catheter. Anaesthesia 2002; 57:1236.

47.Chang CP, Lan YC, Ho WM. Blocked epidural catheter caused by

improper insertion: A case report. The Pain Clinic 2005; 17:335-338.

48.Gupta S, Singh B, Kachru N. “Blocked” Epidural Catheter: Another

Cause. Anesth Analg 2001;92:1616–9.

49.Dharmender C, Elamana V. An Unusual Case of Epidural Catheter

Obstruction. Anesthesiology 1999;91:895.

50.Albright GA: Anesthesia in obstetrics, Maternal, fetal and neonatal

aspects. Menlo Park, Addison-Wesley Publishing, 1978, pp 228-9.

Figure-1: rolling of epidural catheter on its own during insertion

Dr Ashok Jadon, MD DNB MNAMS

Chief Consultant Anaesthesia

Tata Motors Hospital, Jamshedpur-831004

Ashok.jadon@tatamotors.com

Mob: +919234554341