Intraluminal obstruction of epidural catheter due to manufacturing defect.

Sir,

Catheter blockage due to manufacturing defect resulting in inability to deliver the drug is a rare cause of epidural failure. We recently encountered a manufacturing defect of an epidural catheter which manifested as intraluminal obstruction.

A 50-year-old smoker with peripheral vascular disease and gangrene of right lower limb was posted for below knee amputation. He was a known case of hypothyroidism on treatment with oral eltroxin 100 mcg once a day. Under strict asepsis, an 18 G epidural catheter (Perifix, B.Braun Medical Ind. Sdn. Bhd, Penang, Malaysia) was introduced, via the L2-L3 interspace, without any difficulty, through an18 G Tuohy epidural needle, and was fixed at 10 cm. 2% lignocaine with adrenaline 3 ml was injected as test dose, but there was resistance to the flow of the drug. We checked the connector assembly and found it to be in order. The catheter was withdrawn slowly by 0.5 cm twice but the resistance continued. It was presumed that either kinking of catheter or blockade due to blood clot as the cause for resistance and so we decided to redo the procedure. On inspection of the removed catheter we found two areas of flat, compressed zones [Figure 1]. Methylene blue dye was injected to confirm the obstruction.

Figure 1

Site of obstruction

Failure rate of continuous epidural anesthesia varies from 15 to 20%.[12] 14% of all epidural failures were due to technical reasons.[3] Checking the catheter integrity before placement prevents failure of epidural analgesia. Catheters can have manufacturing defects related to connector assembly, faulty marking, intraluminal obstructions, and tensile strength, which could lead to breaking of catheter during insertion or removal.

We want to highlight the need to check the catheter and the assembly by flushing before inserting as the standard of manufacturing is not always infallible.[4] Resistance in drug flow in catheters could be because of improper connection of catheter and injector assembly,[5] clot in the catheter,[6] kinking of catheter, knotting of catheter,[6] or manufacturing defect in catheter assembly/catheter itself.[7]