Failed Epidural Injection - A Rare Cause

Failure to inject drug through epidural catheter may be due to number of reasons, commonly being improper placement, kinking, knotting, and relatively rare causes include manufacturing defect, or obstruction of catheter by a blood clot. Here in this case report we document one of the rare causes of failed epidural injection, due to abnormal stretching and thinning of catheter.

Case Report

A 18 years old male, (172cm, 55 kg), student by profession had an alleged history of road traffic accident. He was brought to the emergency department of our institute. On arrival he was conscious, agitated and oriented to time, place and person. He complained of pain and deformity in left thigh and left shoulder. X ray of left thigh and clavicle – anteroposterior and lateral views were ordered. They reported a displaced fracture in shaft of left femur and an undisplaced fracture of left clavicle. He had no co-morbidities or any surgical and anesthetic exposure in the past. General physical and systemic examination was normal. Airway examination showed normal neck movements, adequate mouth opening with modified Mallampati score of 2. All blood investigations were within normal limits.

For fracture clavicle he was given a clavicular brace for stability. For fracture of femur , he was planned to undergo closed intramedullary nailing. The plan of anesthesia was combined spinal epidural anesthesia. Premedication orders included tablet alprazolam 0.25 mg per oral, tab. rantac 150 mg per oral. After overnight fasting, patient was received in the operating theatre and standard anesthesia monitoring (pulse oximetry, non invasive blood pressure monitor, electrocardiography, capnography) was started.

Under strict asepsis, an 20 G epidural catheter (Perifix, B.Braun Medical) was introduced, via the L2-L3 interspace, through an18 G Tuohy epidural needle, and loss of resistance to air was achieved at 5 cm from the skin. This was uneventful. The epidural catheter was fixed at 10 cm. A test dose of 3ml of 2% lignocaine and adrenaline was injected and any response in heart rate was noted. Spinal anesthesia was achieved with 26 G spinal needle at L3-L4 interspace and 3ml of 0.5 % bupivacaine was injected after free flow of cerebrospinal fluid. Epidural catheter was secured and kept on the left shoulder but not fixed to the patient. After positioning of the patient, the patency of epidural catheter was assessed by injecting 1 ml of normal saline. After achieving a sensory loss till T8 level, patient was positioned for surgery on the fracture table. The duration of surgery was 150 minutes and it was uneventful. The short duration of the surgery did not warrant the need for intra-operative bolus through epidural route. After the completion of surgery the patient was planned to put in the acute pain service, but when the patient was repositioned, abnormal lengthening of epidural catheter was noted. The tactile feel of the catheter was different which confirmed a thinned out catheter. Displacement of catheter was thought so it was decided to remove the catheter. On removing on the adhesive dressing, the catheter fixation was on the same level. A point was noted where the caliber of the catheter was different (normal in the patient end and thinned out at the connector end). Drug was attempted to be pushed through but considerable force led to the abandonment. After locating the catheter where normal caliber was noted, it was cut with a sterile blade and the connector reconnected under sterile conditions, afterwards which the drug was injected without any resistance. Due to uncomfortable fixation on the back of the patient, the decision to remove the epidural catheter was taken. The epidural catheter was then removed after injecting a bolus of 0.125% bupivacaine and 2µg / ml fentanyl (10 ml ). The most probable cause for the thinning out of the catheter might be related to repositioning of the patient and catheter was stretched as the catheter connector assembly might have been lodged somewhere between the sides of the table .

Discussion

Epidural anesthesia has provided the anesthesiologist with the power to control the duration of the anesthesia and also provide post operative pain relief. Although technical difficulty is moderate, but it is mastered with practice. With the development of epidural catheter, it is now one of the common procedures performed.

Inability to inject drug is the dreaded complication which may be due to improper placement of the catheter, kinking , knotting, or displacement of the catheter. Rare causes include occlusion of catheter by blood clot, manufacturing defect in catheter , occlusion in catheter connector assembly or breakage of catheter inside the patient. In this case report the catheter was stretched out and led to thinning of the catheter which made the drug injection impossible. The catheter was correctly placed and all the routine causes of occlusion were ruled out. A similar case report by Khalouf in 1987 where the catheter was stretched and led to abandonment of the procedure.

Various materials have been used for the manufacture of catheters. Many studies found that catheters made from nylon and polyurethane were more resistant than Teflon or polyethylene catheters.

Epidural catheter used in this case was made of polyamide. The tensile strength varies from different catheters but they can with stand enough pressure and require great amount of force to cause any defect.

Repositioning of the patient led to entrapment of the catheter connector assembly in the operating table and led to undue stretching of the catheter. This emphasis the need to fix the catheter connector assembly to the patient (on the shoulder) which may also provide free movement of the patient afterwards too and rechecking of the catheter patency every time the patient is repositioned. Although kinking and knotting are commonly encountered, rare causes like blockage, breakage and stretching should also be taken into consideration. This cause was preventable had the catheter connector assembly been fixed over the shoulder of the patient and thus avoiding the undue removal of the catheter and depraving the patient of post operative analgesia.

Conclusion

After ruling out the common causes of knotting, kinking of the catheter, rare causes like breakage and stretched out catheter may also be taken into consideration. Proper and secured placement of the catheter will avoid such cases.