A case report of a retained and knotted caudal catheter.

Caudal catheters advanced to the lumbar and thoracic regions can be used to provide excellent analgesia for pre-term neonates undergoing major abdominal and thoracic procedures. Despite their frequent use, attention to detail is mandatory to avoid complications related to the medications used or the placement technique. We present a 2-day-old, 2 kg, pre-term infant who was born at 32 weeks gestational age with a tracheoesophageal fistula. Following anesthetic induction, a caudal epidural catheter was placed with the intent of threading it to the mid-thoracic level. The intraoperative and post-operative courses were uneventful with the epidural catheter providing adequate analgesia without the need for supplemental intravenous opioids. During catheter removal, resistance was noted and it could not be easily removed. With repositioning and various other maneuvers, the catheter was removed with some difficulty. On examination of the catheter, a complete knot was noted. Options for catheter advancement from the caudal space to the thoracic dermatomes are reviewed and techniques discussed for removal of a retained epidural catheter.

INTRODUCTION

Given the potential negative effects of systemic opioids on respiratory function in preterm infants, there is continued interest in the use of regional anaesthesia as a means of providing postoperative analgesia. One option is the advancement of an epidural catheter from the caudal space to the thoracic dermatomes. These techniques have been used to provide effective analgesia in pre-term neonates undergoing major abdominal and thoracic procedures.[12] In addition to providing post-operative analgesia, intraoperatively the epidural anaesthesia can be used to supplement general anaesthesia, allowing for a decreased concentration of the volatile agent and avoidance of opioids, thereby allowing early tracheal extubation.[34] Despite their frequent use, attention to detail is mandatory to avoid complications related to the medications used or the placement technique. Most importantly, caudal catheters threaded into the thoracic region have a pre-disposition for malposition as the catheters may double back on themselves or be difficult to advance.[56] We present a 2-day-old, 2 kg, pre-term infant who was born at 32 weeks gestational age with a tracheo-esophageal fistula. A caudal epidural catheter was placed with the intent of threading it to the thoracic dermatomes to provide postoperative analgesia. During catheter removal, resistance was noted and upon removal, a completed knot at the distal end was noted. Options for epidural catheter advancement from the caudal space to the thoracic dermatomes are reviewed and techniques discussed for removal of a retained epidural catheter.

CASE REPORT

Institutional Review Board approval is not required at Nationwide Children's Hospital for the presentation of a single case reports. A 2-day-old, 2 kg, preterm infant was born at 32 weeks gestational age with a tracheoesophageal fistula. VACTERL association was suspected as additional anomalies included imperforate anus for which an exploratory laparotomy and colostomy was planned along with the thoracotomy to repair the tracehoesophageal fistula. The infant was transported from the neonatal Intensive care unit with an endotracheal tube already in place. General anaesthesia included propofol (3 mg/kg) and sevoflurane (expired concentration 1.5-2%) to maintain hemodynamic stability. Neuromuscular blockade was achieved using rocuronium. The patient was turned into the lateral position and a 20 gauge epidural catheter (Arrow FlexTip Plus® caudal catheter, Arrow International, Reading, PA) with a stylet was threaded through a 1.75”, 18 gauge Crawford epidural needle. The catheter was inserted and blindly advanced without resistance to a distance measured previously to approximate the T7 dermatome. Following placement, there was negative aspiration for blood and cerebrospinal fluid. There was no response to a test dose of 0.1 mL/kg of 0.25% bupivacaine with epinephrine 1:200,000. The catheter was fixed at 11 cm at the skin level. The sevoflurane concentration was decreased to less than 0.5 Minimum alveolar concentration. Intraoperatively, bolus doses (0.3-0.7 mL) of 0.125% bupivacaine with epinephrine were administered as needed to control the hemodynamic response to surgical incision. No intraoperative opioids were administered. Post-operatively, the infant was transferred to the neonatal intensive care unit for ventilation and monitoring. No supplement intravenous opioids were administered. The epidural catheter was infused with 1.5% chloroprocaine with fentanyl 0.2 μg/mL at 1.5 mL/h. His trachea was extubated on the 4th fourth post-operative day and the caudal catheter was to be removed on the 5th post-operative day. While attempting to remove the caudal epidural catheter, the distal 1 cm could not be removed from the caudal space. Despite repeated attempts and changing the position of the patient, the catheter could not be removed. A heat pack was applied at the catheter site and left for a period of 1 h. The infant was again repositioned flexed in the lateral position and with repeated flexion and extension and firm pressure applied; the catheter was completely pulled out with the tip intact. On observation of the catheter, there was a fully formed knot at the tip [Figure 1]. On subsequent review of the postoperative radiograph, the catheter could be seen coiling back upon itself in the epidural space [Figure 2]. There was no bleeding from the catheter site. The infant had no complications on subsequent follow-up until hospital discharge.

Figure 1

Photograph demonstrating true knot in the distal end of caudal epidural catheter following removal. The tight wire coil that is within the catheter has been stretched during removal

Figure 2

Radiograph demonstrating that the caudal epidural catheter has doubled back on itself in the epidural space, forming a loop with the potential for knot formation

DISCUSSION

The majority of the neonates who undergo major abdominal and thoracic surgery with general anaesthesia often require a period of post-operative ventilation. The combination of low birth weight, prematurity, extensive upper abdominal and thoracic surgery places the neonate at risk for needing prolonged mechanical ventilation. These issues are further compounded by the respiratory effect of pain related to upper abdominal or thoracic procedures. Regional anaesthesia offers several advantages of decreasing systemic opioids, inhalational anesthetic requirements, reducing the post-surgical stress response thereby facilitating early tracheal extubation.

When considering the options for thoracic epidural catheter placement, there remain concerns regarding the potential for spinal cord damage with direct thoracic placement. As such, techniques have been described whereby a catheter can be advanced from the caudal level to the thoracic dermatomes. In the original study by Bosenberg et al., an examination of human cadaver specimens suggested the feasibility of the technique, which was followed by demonstration of its efficacy in piglets.[1] The authors subsequently used the technique in 20 infants ranging in age from 4 weeks to 5 months and in weight from 2.7 kg to 6.5 kg for biliary surgery. In 19 of 20 patients, the catheter tip was within one vertebra of the goal of T7. In the remaining patient, the tip was at t12. In 14 of 20, slight resistance was noted, which was dealt with by gentle flexion and extension of the back with subsequent catheter insertion. Subsequently as others evaluated the technique, modifications were suggested including the use of fluoroscopy during the placement or the injection of radio-opaque dye to demonstrate catheter location after placement given concerns that the blind technique did not guarantee correct catheter placement.[57] Using epidurography in 20 premature infants undergoing abdominal or thoracic, the position of the epidural catheter was misplaced in three patients.[7] The catheter penetrated the dura in one case, was in an epidural vein in another, and was curled within the epidural space in a third. Another option that has been suggested is the use of a nerve stimulator to identify specific dermatomes as the catheter is advanced.[8] A final option would be the use of a radio-opaque catheter as is our usual practice.[9] The catheter used in our patient is wire reinforced to prevent kinking and infusion issues. As noted in the post-operative radiograph, this simplifies identification of the catheter's location.

As noted in our patient, lack of resistance during insertion does not guarantee correct catheter location. Furthermore, curling of the catheter upon itself can lead to the formation of a knot during removal. Subsequent to this experience, we have modified our practice and now use ultrasound to demonstrate successful cephalad advancement of the catheter from the caudal to the thoracic level.[10] Furthermore, prompt evaluation of the post-operative radiograph should be used to further confirm correct catheter location. This is demonstrated by our current case in that the radiograph obtained on the 1st post-operative day, should have alerted us to the potential for knot formation.

However, some authors suggest that routine radiographic confirmation is not required when the desired length of the catheter has been inserted without resistance, the stylet can be removed freely, and there is ease of injection through the catheter.[4] Based on our experience, we recommend the routine use of ultrasonography during the placement of lumbar and thoracic catheters from the caudal site. In addition, the Arrow FlexTip Plus® catheter offers the advantage of having an internal coil with is radio-opaque.

Once a knot is noted or difficult with removal encountered, there are various options to consider:

Gentle, firm and constant pressure should be applied during catheter removal

It has been suggested that the later position with a flexed spine is ideal for catheter removal when compared to prone or sitting up posture. Significantly less force is required to remove the catheter when the patient is placed in the same position as that of insertion. Changing the position from flexion to extension can break loose the adhesions and aid in the removal[11]

Softening of the tissues around the caudal insertion site can be accomplished by the topical application of heat packs with the caveat to avoid burns or overheating especially in neonates and infants

Saline can be injected while pulling out the catheter[12]

The rigidity of the catheter can be increased by reinserting a guide wire through the lumen. This can also straighten out a kinked catheter to facilitate removal Care should be taken not to exert excessive pressure on the guide wire during insertion since it can rupture the catheter and potentially traumatize the spinal cord

A small incision can be made at the site of insertion

Ultrasound may be helpful in delivering the trapped catheter especially if a knot is formed in the subcutaneous region.

If the catheter is sheared on removal, it has been suggested that the partial catheter can be left in-situ. The residual part will eventually become fibrosed with limited risk of harm to the patient.[13] If the decision is made to leave the catheter in place, it may be appropriate to obtain surgical consultation. Ongoing monitoring is suggested given the risk of infection related to a retained foreign body.[14] Alternatively, if the retained catheter is superficial, then surgical removal can be an option.[15]

Despite the numerous advantages of neuraxial analgesia, complications may occur related to the medications used or the placement technique. As noted in our patient, blind advancement of a caudal catheter may result in inadvertent knot formation. Given the issues that arose with this case, we would suggest the routine use of ultrasound to demonstrate cephalad movement of the catheter tip during advancement. Given its portability and lack of ionizing radiation, ultrasound appears to be the safest and most efficient means of ensuring catheter advancement.