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*Tagesklinik Heilbronn, Heilbronn, Germany;
Kinderkrankenhaus auf der Bult, Hannover, Germany;
Krankenhaus Waldfriede, Berlin, Germany; and
Universitair Medisch Centrum St. Radboud, Nijmegen, The Netherlands
Address correspondence and reprint requests to Jörg Bubeck, MD, Tagesklinik Heilbronn, Allee 38, 74072 Heilbronn, Germany. Address e-mail to dr.bubeck{at}web.de
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Abstract |
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IMPLICATIONS: We investigated the rates of bacterial colonization of tunneled and untunneled caudal epidural catheters and lumbar epidural catheters in children. Tunneled caudal catheters had no more colonization than lumbar-inserted catheters, whereas untunneled caudal catheters showed significantly more colonization.
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Introduction |
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Caudal catheters are not widely used because some authors assume that possible fecal contamination and bacterial colonization of the insertion site leads to an increased risk of ascending infection to the epidural space (5). There are just two prospective studies comparing the colonization and infection rates of caudal epidural catheters with those of lumbar epidural catheters (7,8). The authors reported that the colonization rate of caudal catheters was significantly more rapid than that of lumbar epidural catheters. They concluded that effective measures must be taken to prevent caudal catheters from being soiled and contaminated. A suitable technique could be subcutaneous tunneling of the catheter. We have conducted a prospective trial to answer the following questions: are caudal catheters more frequently colonized than lumbar catheters, and if so, can subcutaneous tunneling reduce the colonization rate of caudal catheters?
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Methods |
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Most catheters were placed under general anesthesia for postoperative pain control. In some adolescents, the catheters were placed under sedation only. The catheter sets used at Hanover Children’s Hospital were the Epidural-Minipack-System® manufactured by Portex, and those used at Olgahospital were the Contiplex-Set® from Braun. Epidural flat filters of the same size (0.2 µm) were used with the Portex and B. Braun sets.
In older children (median age, 9.8 yr), the lumbar route was chosen preferentially, whereas the caudal route was mainly used in children less than 1 yr old. For ethical reasons, we stopped using untunneled caudal catheters in 1994 because early results showed significantly more colonization in this group. The caudal catheters were either inserted percutaneously into the caudal hiatus (untunneled catheter) or tunneled away from the puncture site. Before puncture, we made a stab incision of 2 mm with a lancet. Tunneling was performed subcutaneously with a 20-gauge IV cannula in a cranial direction. This procedure is atraumatic and causes less tissue injury than a surgical incision.
To protect the catheter during the procedure, the Tuohy needle was left in place until the 20-gauge cannula had been inserted (Fig. 1). We then removed the Tuohy needle and pushed the catheter through the 20-gauge cannula. In case of tunneled catheters, the puncture site was covered with a Steri-Strip.
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The catheters were removed when epidural analgesia was no longer required and when intestinal motility had returned. Fever of unknown origin, redness at the insertion site, purulent discharge, or inadvertent disconnection led to early removal of the epidural catheter. Before removal of the catheter, the entry site was disinfected 3 times with 70% alcohol or povidone-iodine solution, and the antiseptic was allowed to dry. Two centimeters of the catheter tip was cultured and sent for microbiological assessment.
Treatment groups were as follows: untunneled lumbar catheter, tunneled caudal catheter, and untunneled caudal catheter. They were matched from all children who expected a long-term painful treatment during the defined investigation time. Because of the higher risk of lumbar catheters causing puncture under general anesthesia, young children (<6 yr) preferably received a tunneled or untunneled caudal catheter, as previously described. For ethical reasons, we stopped using untunneled caudal catheters in 1994. Since then, all caudal catheters have been tunneled. Older children (often >6 yr), who require less frequent surgical treatment or anesthesia for performing puncture, received a lumbar catheter.
We did not change the investigation protocol during the study period. The 
2 test was used for statistical analysis.
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Results |
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Catheters remained in place for a median of 73 h (range, 1.5–352 h). In most cases, antibiotic prophylaxis or therapy was performed with a single dose of cefuroxime. A few children received antibiotic therapy with cefuroxime or cefotaxime three times a day. Children with caudal tunneled catheters were less often treated with antibiotics (63% tunneled caudal catheters versus 97% untunneled caudal catheters and 91% untunneled lumbar catheters) because of the types of surgery.
Some of our patients underwent orthopedic surgery of the lower extremities—for example, surgery for clubfoot. This surgery was usually performed in infants. However, some types of operations are often performed in older children. Because of the age of the children, the types of operation differed between children with caudal catheters and children with lumbar catheters, but there was no difference concerning the type of surgical treatment between the groups with tunneled and untunneled caudal catheters.
Four-hundred-nine (81%) catheters were cultured and sent for bacteriologic examination. Ninety-seven catheters could not be examined because of inadvertent dislodgement, incidental contamination on removal of the catheter, or patient transfer to another hospital before the catheter was removed. Three-hundred-sixty (88%) catheters were sterile. The untunneled caudal catheters exhibited a 3-times-more-frequent colonization rate compared with the other groups (Table 1). There was a significant difference (P < 0.01) in colonization between the untunneled caudal catheters and the lumbar or caudal tunneled catheters. In most cases, we found typical dermal microorganisms (Table 2).
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In all 3 groups, perioperative antibiotic prophylaxis or therapy significantly reduced the rate of colonization (24 colonized catheters of 129 patients without antibiotic treatment versus 25 colonized catheters of 280 patients treated with antibiotics; P < 0.001). This was also true for the colonization rate and the retention times (P < 0.001 for all retention times) and for the rate of redness of catheter entry site. Thirty-seven percent of the children showed redness at the catheter entry site if they were not treated with antibiotics. Perioperative antibiotic prophylaxis reduced the redness at the catheter entry site to 9% (P < 0.001).
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Discussion |
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Studies of infectious complications of long-term epidural catheters were performed by Du Pen et al. (11) and Rauck et al. (12). They reported an overall infection rate of 23.7% and 25%, respectively. Severe complications, such as epidural space infections, were found at a rate of 4.3% and 5.3%, respectively.
The conclusions to be drawn from our results are limited because the caudal epidural group differed significantly from the lumbar epidural group regarding age and weight. In the participating institutions, caudal access to the epidural space was preferred over lumbar access in neonates and infants for reasons discussed in the Introduction. Therefore, the caudal group patients were young, whereas the lumbar epidural group patients were older. We encountered more frequent bacterial colonization of the catheter in younger children compared with older children. We do not know which of the younger children in our study were toilet trained. This has been described previously by McNeely et al. (7) and Kost-Byerly et al. (8), who showed that the colonization rate of caudal catheters in children younger than three years was more than in older children. The incidence of redness of the insertion site did not differ significantly in their studies.
The prevalent germ we found in colonized caudal catheters was Staphylococcus epidermidis, and this is in accordance with the results of other investigators (7,8,13). We do not know whether the bacterial colonization reached the epidural space or whether the catheters were contaminated subcutaneously on removal by the deeper parts of the catheter entry site that may not have been sufficiently reached by antiseptics. We did not find a significant correlation between antibiotic therapy, predominantly with cefuroxime, and the bacterial colonization rate between groups.
All catheters that remained in place for <24 hours were sterile. In catheters used for more than 24 hours, the colonization rate was more or less constant and was not related to the application time. A positive correlation was found between redness of the catheter entry site and bacterial colonization. Redness of the entry site was noted in 14% of all catheters evaluated. The colonization rate in these patients was twice as much as in patients without local inflammatory signs (23% versus 10%). It remains unclear whether colonization started at the tip of the inserted catheter or was due to the catheter being pulled back through the red skin. Artificial contamination was prevented by careful disinfection of the skin and strictly sterile procedure of cutting and storing the tip of the catheter. Kost-Byerly et al. (8) and Lakshmi et al. (14) did not find a corresponding correlation in their study. For children with perioperative prophylaxis or therapy with antibiotics, we found significantly less colonization for the different retention times. Antibiotics also reduced the rate of redness at the catheter entry site. Because of the number of patients in the group with caudal untunneled and lumbar catheters was too small, we do not have results of the effect of antibiotic administration on redness of catheter entry or on colonization at different retention times in these groups.
There are case reports describing epidural abscess formation with continuous lumbar and caudal epidural analgesia (15,16) in children, even though the risk of an epidural infection is regarded to be small (8,9,17,18). In a review of 1620 pediatric cases, Strafford et al. (9) did not report any epidural infection. Broadman (19) reviewed approximately 3500 pediatric cases and found a similar result. Several techniques to reduce the bacterial colonization of epidural catheters have been investigated. Abouleish et al. (10) have evaluated the effectiveness of different techniques of skin disinfection. Spraying the skin with povidone-iodine and removing the excess of fluid after one minute is regarded as adequate. The Centers for Disease Control guidelines for prevention of intravascular catheter-related infections (20) recommend 2% chlorhexidine-based preparations, as well as tincture of iodine or 70% alcohol for skin disinfection. Other studies have evaluated special dressing techniques for epidural catheters, such as chlorhexidine dressing or barrier flaps (13,21). De Cicco et al. (22) studied the time-dependent efficacy of bacterial filters for epidural catheters and the influence of filter-changing frequency on bacterial contamination. Their data showed a significant positive relationship between the incidence of catheter tip colonization and the filter-changing frequency. They also found an unmodified antimicrobial function of Portex and Braun filters for at least 60 days. They concluded that it appears feasible to reduce the frequency of filter changing during long-term epidural catheterization.
Tunneling of percutaneous catheters is mainly used in the long-term treatment of chronically ill patients (23–25). We investigated whether subcutaneous tunneling in a cranial direction is effective in reducing bacterial colonization of caudal epidural catheters. By this technique, the catheter entry site is displaced to the lumbar region and out the diaper area. Our results indicate that a significant reduction of the colonization rate may be achieved by cranial tunneling (11% versus 29%), although in our study the risk of colonization in patients with tunneled caudal catheters could have been increased because of the smaller number of patients receiving antibiotics. The demographic data between the groups with tunneled and untunneled catheters were comparable. However, the number of patients with untunneled catheters was much smaller than the number of patients with tunneled catheters. A preliminary analysis confirmed our assumption that the colonization rate differs between techniques; therefore, the untunneled technique was abandoned by many of the participating anesthesiologists.
We conclude that tunneling of caudal catheters decreases the colonization rate to levels similar to those found in lumbar epidural catheters (10.5% versus 9.4%, respectively). We believe that this technique is a simple and effective way to use caudal epidural catheters in children. The results of our investigation indicate that tunneling of caudal catheters may decrease the risk of epidural infection.
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  H.-G. Ryu, J.-H. Bahk, C.-J. Lee, and Y.-J. Lim The coiling length of thoracic epidural catheters: the influence of epidural approach angle Br. J. Anaesth., March 1, 2007; 98(3): 401 - 404. [Abstract] [Full Text] [PDF]
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