◊ BACKGROUND:
Bacterial colonization of peripheral nerve catheters is frequent, although infection is relatively rare. With central venous catheters, the tunneling of the catheter into the subcutaneous tissue significantly decreases catheter colonization and catheter-related sepsis. We evaluated the incidence of bacterial colonization in adult patients with tunnelized perineural nerve catheters.
◊ METHODS:
Peripheral nerve catheters placed under sterile conditions for postoperative analgesia were evaluated prospectively. After removal, they were analyzed for colonization. Quantitative culture was used as described by Brun-Buisson for intravascular catheters. The site of insertion was monitored daily for any signs of infection.
◊ RESULTS:
Four-hundred-two patients were included in the study during a 2-yr period. The mean duration of peripheral nerve catheters was 48 h (47-50.4). Positive culture occurred in 25 catheters, indicating that the incidence of colonization was 6.22% (3.8-8.5). The microbiological analysis of the catheter tip cultures revealed coagulase-negative staphylococci in 72%. Twenty-two catheters of 25 catheters each had one microorganism, and for three catheters, two microorganisms were identified. No infection was found in any patient.
◊ CONCLUSIONS:
The incidence of perineural catheter colonization is low with subcutaneous tunneling. Controlled randomized studies are warranted to determine whether this procedure decreases the risk for infection.
◊ Reviewed by A. Borgeat, MD, PhD,
Professor, chief of the department,
Orthopedic University Hospital Balgrist, Zurich, Switzerland
Continuous peripheral nerve block is becoming more and more the gold standard for the management of perioperative pain, especially after major orthopedic surgery. Use of this technique is still increasing since it has been shown to have a major impact on surgical outcome. One of the main drawbacks of continuous analgesia through perineural catheter is the risk of infection, which has received little attention to date. However, infection in a surgical setting using prosthetic material may have disastrous consequences. Therefore, the study conducted by Compère (1) et al is of topical interest and utmost clinical importance!
Previous studies have found a quite high incidence of catheter colonization, up to 57% of femoral catheters within 48 h. Tunnelling of the catheter has been shown to be very efficacious to prevent its dislocation, but its role to lower the rate of colonization or to provide an extra benefit regarding the development of perineural catheter site colonization is still controversial and indeed has never been studied systematically.
This question was investigated in this open prospective study of 402 patients having a perineural catheter. The study methodology was adequate. Aseptic precautions included cap, gown, facemask and sterile gloves. The skin was disinfected twice, before catheter placement and prior to its removal. Microbiology laboratory techniques were adequate as well and clear distinction between local inflammation and infection was made.
Overall incidence of positive cultures was 6.2%. Coagulase-negative staphylococcus was the most frequent microorganism. In a subgroup of trauma patients (7.2% of all patients) incidence of catheter colonization was higher (10% vs 5.9% for elective surgery).
Authors conclude that tunnelling may decrease the incidence of catheter colonization. Their results are in accordance with those of other studies using this technique (2,3). However, one has to be cautious with this conclusion as results may have simply been due to skin disinfection before removal of the catheter which is still not standard practice yet. Control groups without doing this and without tunnelling would have made the study more conclusive (4). However, the question raised by the authors is important and future investigations are warranted. The higher incidence of colonization in the subgroup of trauma patients as found in this study confirms previous results (4,5), but unfortunately the number of patients was low. Other interesting findings of this investigation are the confirmation of the frequent colonization with coagulase-negative staphylococci and the higher incidence of catheter colonization at the inguinal crease (femoral block and fascia iliacal block).
Further studies are needed before tunneling of the catheter can be considered a valid technique to lower the incidence of colonization. In any case it is to be recommended for securing the catheter. The observed higher rate of colonization at the inguinal crease should be taken into account and warrant strict aseptic measures at this location.
◊ REFERENCES
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Bacterial colonization after tunneling in 402 perineural catheters: a prospective study. Anesth Analg 2009;108:1326-30.
2. Borgeat A, Ekatodramis G, Kalberer F, Benz C.
Acute and nonacute complications associated with interscalene block and shoulder surgery: a prospective study. Anesthesiology 2001;95:875-80.
3. Borgeat A, Blumenthal S, Lambert M, Theodorou P, Vienne P.
The feasibility and complications of the continuous popliteal nerve block: a 1001-case survey. Anesth Analg 2006;103:229-33, table of contents.
4. Capdevila X, Pirat P, Bringuier S, Gaertner E, Singelyn F, Bernard N, Choquet O, Bouaziz H, Bonnet F.
Continuous Peripheral Nerve Blocks in Hospital Wards after Orthopedic Surgery: A Multicenter Prospective Analysis of the Quality of Postoperative Analgesia and Complications in 1,416 Patients. Anesthesiology 2005;103:1035-45.
5. Neuburger M, Buttner J, Blumenthal S, Breitbarth J, Borgeat A.
Inflammation and infection complications of 2285 perineural catheters: a prospective study. Acta Anaesthesiol Scand 2007;51:108-14.
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