Anesth Analg 2004;99:259-261
© 2004 International Anesthesia Research Society
doi: 10.1213/01.ANE.0000120082.85977.F7
REGIONAL ANESTHESIA
Inadvertent Cervical Epidural Catheter Placement via the Caudal Route Using Electrical Stimulation
Ban C. H. Tsui, MD MSc, FRCP(C), and
Stephan Malherbe, MBChB MMed, FCA(SA)
Department of Anesthesiology and Pain Medicine, University of Alberta Hospitals, Edmonton, Alberta, Canada
Address correspondence and reprint requests to Ban C. H. Tsui, MD, MSc, FRCP(C), Department of Anesthesiology and Pain Medicine, University of Alberta Hospitals, 3B2.32 Walter Mackenzie Health Science Centre, 8440-112 St., Edmonton, Alberta, Canada T6G 2B7. Address e-mail to btsui{at}ualberta.ca
 |
Abstract
|
|---|
Inadvertent placement of an epidural catheter in the cervical region via the caudal route is described in an infant who underwent revision of a fundoplication. We attempted electrical stimulation (the Tsui test) via the epidural catheter to confirm correct placement and positioning of the catheter tip. In this case, the epidural catheter was inadvertently advanced to the cervical region, resulting in stimulation of the phrenic nerve. These diaphragmatic twitches were misinterpreted as chest wall twitches, and it was incorrectly assumed that the catheter was in the thoracic region. To avoid misinterpretation of the stimulation level, the catheter should be continuously stimulated while it is advanced. We also recommend that the catheter length be estimated before insertion (although doing so did not help in this case) and that the catheter position be radiographically confirmed after surgery.
IMPLICATIONS: To avoid misinterpretation of the stimulation level with the Tsui test, the epidural catheter should be continuously stimulated while it is advanced. The length of epidural catheter required should be predetermined before insertion, and the position of the catheter should also be radiographically confirmed after surgery.
|
Introduction
|
|---|
Thoracic epidural catheters placed via the caudal route are an effective, safe, and easy method of providing postoperative analgesia in neonates and infants (1). Electrical stimulation (the Tsui test) via the epidural catheter has been described as a reliable technique for confirming correct catheter placement (2). This report describes a case in which the catheter was inadvertently advanced to the cervical region, resulting in stimulation of the phrenic nerve and twitches in the chest wall.
|
Case Report
|
|---|
A 6-mo-old male infant (6.1 kg) underwent revision of fundoplication and a gastrostomy tube. His medical history included Prader-Willi syndrome, atrial septal defect, ventricular septal defect, and recurrent aspiration pneumonia.
Anesthesia was induced with IV propofol 4 mg/kg and remifentanil 3 µg/kg and was maintained with desflurane in air and oxygen. After induction, a thoracic epidural catheter was placed via a caudal approach with the patient on his left side by an anesthesiologist inexperienced with the technique. After 7 mL of normal saline was injected into the epidural space during advancement, the epidural catheter (Epidural Positioning System with the Tsui test; Arrow International Inc., Reading, PA) was eventually advanced to a predetermined length of 20 cm. No muscle twitching was noted on the chest or abdominal wall when an electrical current of 10 mA was used to stimulate the epidural catheter at what was assumed to be this level. The catheter was then advanced an additional 4 to 5 cm until a twitch was observed in the left anterior chest wall at the T6-7 region. The catheter was fixed, and the patient was paralyzed with IV rocuronium 1 mg/kg. An initial loading dose of 0.25% bupivacaine 4 mL was administered over 45 min. After 60 min, an epidural infusion of 0.1% bupivacaine with fentanyl 1 µg/mL was started at 2.4 mL/h.
The procedure lasted 2 h. The patient remained hemodynamically stable throughout the procedure, with pulse rate varying between 120 and 140 bpm and arterial blood pressure between 120/70 and 90/50 mm Hg. He received no other analgesics during the procedure. The neuromuscular block was reversed at the end of the procedure, and spontaneous respiration immediately returned. He was tracheally extubated in the operating room and appeared comfortable.
A radiograph taken to confirm the position of the epidural catheter revealed the tip to be at the C3-4 level (Fig. 1). On the basis of this radiograph, the catheter was withdrawn approximately 5 cm and reconfirmed with another radiograph to be at the T7 level. Analgesia was excellent over the following 3 days, and the epidural catheter was removed on postoperative Day 3. The patient was discharged after 8 days.
View larger version (169K):
[in this window]
[in a new window]
|
Figure 1. Anteroposterior chest radiograph. The arrow shows the tip of the epidural catheter at the C3-4 level.
|
|
|
Discussion
|
|---|
Most thoracic epidural catheters placed via the caudal route in infants and small children are advanced to the thoracic region without difficulty (1–5). The ease of threading the catheter, however, does not guarantee successful placement of thoracic epidural catheters inserted via this route (3,4,6). A problem often encountered is curling of the catheter between the levels of T12 and L5 (5). This can be difficult to detect clinically during insertion, and it has been recommended that the advancement of the catheters be guided radiographically when using the caudal approach (3,7).
Ideally, one should be able to detect the epidural catheter location during placement to allow the necessary adjustments to be made. Historically, there has been no objective way of determining epidural catheter location besides radiological imaging. A described technique of applying an electrical stimulus to the tip of the epidural catheter can provide information about the position of the catheter during insertion (1,2,8,9). The Tsui technique uses a modified epidural catheter system that consists of a flexible-tipped catheter with a removable stylet, an IV T-extension, and an electrocardiogram (ECG) adapter with the ability to connect to a nerve stimulator. A commercially available product (the Epidural Positioning System with the Tsui test) is often used in our institution. The anode lead of a nerve stimulator is connected to the patient as a grounding site, and the cathode lead is connected to the metal hub of the ECG adapter. After the catheter is primed with normal saline, an electrical current (1–10 mA at 1 Hz) can be applied to the tip of the epidural catheter. Stimulation of spinal nerve roots causes muscle twitching in the corresponding myotomes, which then indicates the position of the catheter tip. Tsui et al. (1) recommend that the catheter be continuously stimulated while it is advanced so that the level of muscle twitch can be observed to advance from the lower limb muscles to the upper abdominal muscles and finally to the intercostal muscles as the catheter is threaded cranially. The main advantage of the Tsui test is, therefore, to diagnose those catheters that kink or curl during advancement. In retrospect, the cervical placement of the epidural catheter in this case may have been avoided if the catheter had been continuously stimulated while it was advanced. Tsui et al. (1) also recommend that the length of the epidural catheter to be inserted be predetermined before thoracic epidural placement via the caudal approach is attempted.
In this case, the epidural catheter was inadvertently advanced to the cervical region, resulting in stimulation of the phrenic nerve and twitches in the chest wall. This was misinterpreted as the catheter being in the thoracic region, resulting in improper catheter placement. Catheter placement errors can be made by misinterpretation of muscle twitches due to extensive overlap of muscular innervation by spinal nerves (10). In addition, phrenic nerve stimulation can be misinterpreted as intercostal muscle stimulation, as seen in this case. Interpretation of the Tsui test at the midthoracic levels (T7 to T10) can also be difficult and may manifest in either twitching of the intercostal (T7 to T10) or the rectus abdominus (T7 to T12) muscles (10). The precise level of muscle stimulation is also difficult to detect in small infants, and one may occasionally misinterpret the exact intercostal muscle group being stimulated.
In our case, the epidural catheter was initially advanced to a predetermined length of 20 cm. Interestingly, however, no motor response was observed when the catheter was stimulated at this site. In retrospect, the catheter was probably at the T7 level, because the catheter was initially advanced approximately 4 to 5 cm from this location and later pulled back 5 cm, at which point it was reconfirmed by radiograph to be at T7. Saline causes dispersion of the epidural space to allow the catheter to advance more easily. A loss of a motor response has been demonstrated when saline is injected after needle localization of peripheral nerves, with a return of response after 5% dextrose in water injection (11). A possible explanation of this phenomenon is that saline causes dispersion of the current, which may lead to loss and, therefore, inaccurate interpretation of motor responses. This shunting and dispersion of current by the conducting solution is well known in other medical fields. In urology, nonconducting solutions of glycine 1.5% in sterile water are used instead of normal saline for transurethral resection of prostate surgery, because the current is dispersed from the tip of the resectoscope by normal saline, thereby inhibiting its cutting properties (12).
With advancement of the epidural catheter to C3, one might have expected pulmonary compromise because of the blockade of the phrenic nerve. Studies have shown that pulmonary function is not significantly affected under cervical epidural anesthesia (13–15), although progressive respiratory depression has occurred with epidural injection of 0.5% bupivacaine (16,17). Fortunately, respiratory integrity was well maintained in our patient.
In summary, we recommend that the length of the epidural catheter be predetermined before insertion. To avoid misinterpretation of the stimulation level, the catheter should be continuously stimulated while it is advanced so that the level of muscle twitches can be observed to advance from the lower limb muscles to the upper abdominal muscles and finally to the intercostal muscles as the catheter is threaded cranially. The final position of the catheter should be radiographically confirmed after surgery until ample experience has been accumulated in using the Tsui test. We also alert the reader to the fact that excess saline injected into the epidural space may lead to dispersion of the current and loss of a motor response after electrical stimulation.
|
Acknowledgments
|
|---|
Supported in part by an Education and Research Fund, Department of Anesthesiology and Pain Medicine, University of Alberta Hospitals, Edmonton, Canada, and a Clinical Investigatorship Award, Alberta Heritage Foundation for Medical Research, Alberta, Canada.
|
Footnotes
|
|---|
The principal author has a patent license agreement (US Patent 6190370) with Arrow International Inc. (Reading, PA) for the epidural kit described in this article.
|
References
|
|---|
- Tsui BCH, Seal R, Koller J, et al. Thoracic epidural analgesia via the caudal approach in pediatric patients undergoing fundoplication using nerve stimulation guidance. Anesth Analg 2001; 93: 1152–5.[Abstract/Free Full Text]
- Tsui BCH, Gupta S, Finucane B. Confirmation of epidural catheter placement using nerve stimulation. Can J Anaesth 1998; 45: 640–4.[Abstract/Free Full Text]
- Gunter JB, Engl C. Thoracic epidural anesthesia via the caudal approach in children. Anesthesiology 1992; 76: 935–8.[ISI][Medline]
- Casta A. Attempted placement of a thoracic epidural catheter via the caudal route in a newborn. Anesthesiology 1999; 91: 1965–7.[ISI][Medline]
- Busoni P. Continuous caudal block. In: Saint-Maurice C, Steinberg OS, eds. Regional anaesthesia in children. Fribourg, Switzerland: Mediglobe, 1990: 88–94.
- Blanco D, Llamazares J, Rincon R, et al. Thoracic epidural anesthesia via the lumbar approach in infants and children. Anesthesiology 1996; 84: 1312–6.[ISI][Medline]
- Valairucha S, Seefelder C, Houck CS. Thoracic epidural catheters placed by the caudal route in infants: the importance of radiographic confirmation. Paediatr Anaesth 2002; 12: 424–8.[ISI][Medline]
- Tsui BCH, Gupta S, Finucane B. Determination of epidural catheter location using nerve stimulation in obstetric patients. Reg Anesth Pain Med 1999; 24: 17–23.[ISI][Medline]
- Tsui BCH, Seal R, Entwistle L. Thoracic epidural analgesia via the caudal approach using nerve stimulation in an infant with CATCH22. Can J Anaesth 1999; 46: 1138–42.[Abstract/Free Full Text]
- Goobie SM, Montgomery CJ, Basu R, et al. Confirmation of direct epidural catheter placement using nerve stimulation in pediatric anesthesia. Anesth Analg 2003; 97: 984–8.[Abstract/Free Full Text]
- Tsui BCH. Electrophysiological effect of injectates on peripheral nerve stimulation [abstract]. Reg Anesth Pain Med 2003; 28: A2.
- Monk TG, Weldon BC. The renal system and anesthesia for urologic surgery. In: Barash PG, Cullen BF, Stoelting RK, eds. Clinical anesthesia. 3rd ed. Philadelphia: Lippincott-Raven, 1997: 945–74.
- Wittich DJ Jr, Berny JJ, Davis RK. Cervical epidural anesthesia for head and neck surgery. Laryngoscope 1984; 94 (5 Pt 1): 615–9.[ISI][Medline]
- Nystrom UME, Nystrom NA. Continuous cervical epidural anesthesia in reconstructive hand surgery. J Hand Surg 1997; 22: 906–12.
- Stevens RA, Frey K, Sheikh T, et al. Time course of the effects of cervical epidural anesthesia on pulmonary function. Reg Anesth Pain Med 1998; 23: 20–4.[ISI][Medline]
- Bonnet F, Derosier JP, Pluskwa F, et al. Cervical epidural anaesthesia for carotid artery surgery. Can J Anaesth 1990; 37: 353–8.[Abstract/Free Full Text]
- Capdevila X, Biboulet P, Rubenovitch J, et al. The effects of cervical epidural anesthesia with bupivacaine on pulmonary function in conscious patients. Anesth Analg 1998; 86: 1033–8.[Abstract]
Accepted for publication January 13, 2004.
Top
Abstract
Introduction
