Reduction of Microbial Colonization with a Chlorhexidine-Coated Dressing for External Ventricular Drain (EVD)—A Prospective, Randomized, Controlled, Clinical Trial (EVDAI Study)

Aim: EVD-associated infection (EVDAI) is one of the most common neurosurgical complications with a prevalence around 10%.¹ It is caused most likely due to retrograde infection from skin flora in the post-operative period.² Chlorhexidine (CHX)-impregnated dressings successfully prevent central venous catheter colonization and catheter-related bloodstream infections.³ In this study, a CHX-containing dressing (CHX-dressing) at the skin exit point of EVDs is evaluated in reducing the quantity of microorganisms (CFU/cm²) after a time period of 5 days, compared to non-antimicrobial polyurethane dressing (control). Skin microbial colonization serves as a surrogate marker for EVD-associated infections. Methods: A randomized, controlled, clinical single-centre trial comparing the differences of microorganisms (CFU/cm²) after a time period of 5 days (primary endpoint) as surrogate marker for EVDAI in patients treated by EVD with CHX-dressing at the skin exit point versus control. Primary endpoint is number of colony forming microorganisms (CFU/cm²) in cultured skin swabs taken at dressing-changing time points. Secondary endpoints are CSF cultures every 2nd day and cultures of the sonicated catheter tip after explantation. The null hypothesis was that bacterial colonization (CFU/cm²) of the EVD skin exit point after 5 days compared to baseline (bacterial regrowth since baseline) in subjects treated with CHX dressing is equal to controls. The microbial load of the catheter tip (sonication) and CSF might be reduced by this external intervention. Results: In this ongoing trial, n = 38 patients have been randomized. N = 18 male (47.4%), n = 20 female (52.6%). Mean age was 55 years. N = 23 (60%) EVDs have been placed right frontal, 11 (30%) EVDs left frontal, 5 (10%) EVDs bilateral. N = 21 (48%) have been included into the CHX group, n = 23 (52%) into the placebo group. Mean duration in situ was 8.1 days and did not differ within groups. N = 29 (76%) subjects had >5 days duration of EVD. Overall duration of EVD was 351 days. EVD days counted for analysis are 322 (91.7%) after exclusion of n = 9 (23.7%) patients. Bilateral EVD's were counted individually. Median colonization of the skin before operation was 10.5 CFU/plate in both groups, after EVD-implantation 5 CFU/plate and 7 CFU/plate in CHX-group and the placebo-group respectively. After 5 days, no colonization was shown in the CHX-group, whereas 4 CFU/plate were detected in the placebo group. After 10 days, 15 days, and the day of EVD-explantation, colonization was slightly higher in the placebo group. Microbes cultured were mainly coagulase-negative staphylococcus (CNS), St. aureus, corynieform rods and bacillus spp. After 5-10 days, mainly St. epidermidis and St. capitis showed positive cultures. Proven EVDAI were found in 8 cases (19%), n = 2 (10%) in the CHX-group and n = 6 (29.6%) in the placebo group, suspected EVDAI in n = 10 (23%), n = 2 (10%), and n = 8 (34.7%) respectively. Conclusions: Prevention of EVDAI leads to decreased morbidity and mortality of patients, and thus reducing the costs of treatment. Significant reduction of catheter-related infections with CHX has been shown in previous studies for central-venous catheters³ and EVD⁴ amongst other interventions.⁵ Our preliminary results show a promising efficacy in reducing EVD colonization and EVDAI.

Acknowledgments: This trial is supported by 3M Tegaderm (offering 3M Tegaderm CHG and 3M Tegaderm Transparent Film Dressings) and the Neurochirurgie Forschungsfonds, Departement Chirurgie, Universitätsspital Basel.

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