Transparent film dressings for intravascular catheter exit-site

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1 The Journal of Vascular Access 2004; 5: REVIEW Transparent film dressings for intravascular catheter exit-site M. GALLIENI Renal Unit, Azienda Ospedaliera San Paolo, Milano - Italy ABSTRACT: Transparent polyurethane film is recommended for catheter site insertion dressing by the American guidelines for the prevention of infections associated with intravascular catheters. It has been proven to offer the advantages of excellent adhesion, firm support of the catheter, good tolerability, ease of application and fewer replacements per catheter lifetime. The last two features save nursing time and result in healthcare cost savings. (The Journal of Vascular Access 2004; 5: 69-75) KEY WORDS: Venous catheter, Dressing, Polyurethane, Infection, Permeability INTRODUCTION The CDC Guidelines for the Prevention of Infections associated with Intravascular Catheters published in 2002 recommend several types of catheter site dressings, including transparent polyurethane film, unless the site of insertion is oozing blood or the patient is diaphoretic (1). Transparent polyurethane film ( transparent dressings ) has become popular because it reliably secures the catheter, it enables immediate visual inspection of the catheter insertion site, does not have to be changed frequently and enables the patient to bathe or shower without any concern about wetting the dressing (1). This article reviews the issues raised in the literature related to transparent dressing use at catheter insertion sites. Risk of infection In the 1980s concern was raised about the risk of an increase of infection rates due to the accumulation of fluid under transparent dressings, which could be an excellent culture medium for pathogens. However, in the early 1990s the results of a metaanalysis of 14 prospective studies, in which transparent dressings were compared to sterile dry gauze dressing in over 1,500 central intravenous catheter carriers and over 5,000 peripheral venous catheter carriers, did not find any significant difference in the incidence of infections (i.e. bacteremia or catheter sepsis) in patients with central venous catheters, and of infiltration or skin colonization in patients with peripheral venous catheters. This meta-analysis showed that the use of transparent dressings was associated with a significant increase in the risk of catheter-tip colonization as compared to the use of gauze dressings. However, the risk factor has a very low predictive value (17%) for systemic infections and the outcome could have been due to failure to correct for a number of more important factors, such as frequency of dressing replacement, differences in duration of catheter use and usage of topical antibiotics (2, 3). The results of the meta-analysis are consistent with the favorable outcome of previous studies addressing the issue of local flora overgrowth under transparent dressings. A study with a 2X2 factorial design comparing transparent dressings versus no dressing and chlorhexidine disinfection versus no disinfection on the intact upper arm skin in 55 patients showed that transparent dressings significantly reduced aerobic skin flora growth versus no dressing (mean cfu 202 vs 522) and that the reduction was higher when the areas had been disinfected previously (mean cfu 35 vs 378) (4). In another study three different transparent dressings and a gauze dressing were applied onto the Wichtig Editore, /069-07$15.00/0

2 Transparent film dressings for intravascular catheter exit-site Fig. 1a - Aerobic skin flora growth on the volar forearm of 50 healthy volunteers and 49 in-patients after 3 days of occlusion by gauze and three brands of transparent polyurethane dressings was significantly lower than after 3 days of occlusion with plastic Saran wrap (p < 0.05) or on exposed skin not protected by any dressing# (p < 0.05). Fig. 1b - Gram-negative skin flora growth on the volar forearm of 50 healthy volunteers and 49 in-patients after 3 days of occlusion by gauze and three brands of transparent polyurethane dressings was significantly lower than after 3 days of occlusion with plastic Saran wrap* (p < 0.05). volar side of the forearm of 50 healthy volunteers and 49 hospitalized patients, 25 of whom also received antibiotic treatment. They were compared to controls consisting of one exposed skin site (no dressing) and one covered with moisture-retaining vinylidene film (Saran Wrap), with the aim to evaluate aerobic skin flora and Gram-negative flora growth after 3 days of continuous application. The results are shown in Figures 1a and 1b. It is evident that aerobic floral growth was significantly lower either under gauze dressings or under transparent dressings, compared to under the plastic Saran Wrap (p<0.05) or to the exposed area not covered by any dressing at all (p<0.05). In addition, Gramnegative skin flora growth under both the gauze dressing and the transparent dressings was also significantly lower than in the plastic Saran wrap group (p<0.05) (5). A randomized, controlled clinical trial involving a total number of 2,088 Teflon catheters in 1,259 patients, allocated to either sterile gauze dressing replaced every other day, or one of three different types of dressing left on for the lifetime of the catheter (gauze, transparent dressing, iodophortransparent dressing), not only confirmed that transparent dressings are not associated with increased skin flora regrowth, but also resulted in a similar rate of catheter-related infections in the 4 dressing groups: 4.6% with gauze independently of dressing change frequency, 6.1% with transparent dressing and 5.2% with iodophor-transparent dressing (p, NS) (6). The issue of infections with intra-arterial catheters was addressed by a prospective, randomized trial comparing gauze and tape replaced every 2 days, a traditional transparent dressing replaced every 5 days and a high permeable dressing also replaced every 5 days in a total of 442 adult patients with a pulmonary artery catheter. No significant difference in the rate of local infections was found: 20.0% with gauze, 25.2% with the traditional transparent dressing and 20.5% with the high permeable dressing; the bloodstream infection rates were 1.6%, 0.8% and 1.1%, respectively (7). A subsequent meta-analysis also resulted in no difference in the risk for central venous catheter-related blood stream infection using transparent dressings compared with gauze dressings to cover catheter insertion sites (8). Mermel drew the following conclusion in a recent review on the prevention of intravascular catheter-related infections: on the basis of all available evidence, the choice of central venous catheter dressing may be a matter of preference and cost (9). A Cochrane review published in 2003 revealed the lack of suitably designed studies for inclusion in a metaanalysis and reached the same conclusion i.e. that at present the choice of dressing of central venous catheters can be based on patient preference (10). Another important issue regarding the risk of infection is the time interval protocol for dressing changes. Rasero et al (11) addressed this question in a randomized, multicenter study of 399 bone marrow transplant patients randomly allocated to receive tunneled central venous catheter dressing changes every 5 or 10 days, and non-tunneled CVC dressing changes every 2 or 5 days. The Tegaderm TM transparent dressing was used in all patients. Tegaderm TM consists of a thin polyurethane backing with a hypoallergenic, non-latex adhesive. The dressing 70

3 Gallieni Bacterial Count at Day 5 (N=54) Evaporation Through Dressing at Day 5 (N=49) Mean log 10 CFU/cm gm/m 2 /24 hr Uncovered Skin Tape & Gauze Tegaderm Tegaderm HP Opsite IV3000 Measurement of moisture vapor passing through dressings Uncovered Skin Tegaderm HP Tape & Gauze Opsite IV3000 Tegaderm Fig. 2a - Investigation of bacterial growth with transparent dressings. No significant differences in bacterial counts among the three transparent dressings were evident at 5 days. Significantly lower bacterial counts with all three transparent dressings compared with tape and gauze and uncovered skin. Fig. 2b - Moisture handling properties of transparent dressings using evaporimetry. When measured on skin, no significant difference in evaporation of moisture through the three different transparent dressings. Although evaporation rates were significantly higher with tape and gauze, bacterial counts were significantly higher, as illustrated in Figure 2a. is waterproof, breathable and impermeable to liquids, bacteria and viruses. They found that patients receiving CVC dressing changes at longer intervals did not show a significant increase in the rate of local infections, while significantly reducing patient discomfort and costs (11). The issue of permeability The issue of the risk of skin flora overgrowth promoted by the occlusion caused by the application of transparent dressings for days was also addressed by comparing bacterial counts after their application with those after the application of high permeable dressings. Permeability of the dressing was measured by means of the Moisture Vapor Transmission Rate (MVTR), which is the measurement of water vapor diffusion through a material within a given time period. Studies consistently showed that higher permeability did not result in lower bacterial counts under the dressings or in a lower infection rate. In a prospective, randomized, balanced block, controlled clinical trial by Aly et al (12), three transparent dressings with different MVTRs (Tegaderm TM, Tegaderm TM HP and OpSite TM IV3000) were compared to tape and gauze and uncovered skin in terms of bacterial counts and moisture handling properties. Five days after standard disinfection of the chest with isopropyl alcohol and povidone-iodine swabs, higher MVTR dressings did not result in lower bacterial counts. On the contrary a significantly higher MVTR of gauze and tape (p<0.0001) was associated with significantly higher bacterial counts (p<0.0001) (Fig. 2a and 2b). Treston-Aurand et al pointed out that for semipermeable, polyurethane dressings, there have been differing results regarding the association with microbial growth under the dressing and the risk of subsequent CVC-associated infection. They described a positive experience in terms of the impact of a highly permeable dressing (OpSite TM IV3000) on CVC-associated infection (13). The OpSite TM dressing is made by a film with an MVTR of 3000g/m 2 /24hr, making it significantly more permeable to water vapour than ordinary films in the presence of moisture (14,15). However, the comparison between the traditional transparent dressing Tegaderm TM and the semi-permeable transparent dressing Opsite TM IV3000, applied to the insertion site of a central venous catheter in 100 critically ill patients with liver disease for a mean period of 71

4 Transparent film dressings for intravascular catheter exit-site 5.6 days, did not disclose any important difference. Blood was found under the dressing in 70% of patients in the Tegaderm TM group vs 60% in the Opsite TM group; exudate was found in 32% and 23%, and microorganisms were isolated from the entry site wound in 64% vs 54%, respectively (p, NS). Three patients, all in the Opsite TM group, had evidence of systemic infections, whereas 8 patients had evidence of local infections, 4 in each group (16). The addition of a disinfectant Another approach to the issue of the risk of skin flora overgrowth has been the development of transparent dressings that release an antibacterial agent, such as silver ions, which are particularly effective against resistant organisms known to be frequently involved in infections of catheter sites, such as methicillin-resistant Staphylococcus aureus (17). The results of a preliminary study, in which such a product was compared to the traditional transparent dressing (Tegaderm TM ) in 31 patients admitted to an intensive care unit and requiring the insertion of an arterial or central venous catheter, were disappointing, as the addition of silver ions did not result in a reduction in bacterial growth (17). Adhesion Adhesion of transparent dressings is considered to be excellent (1). Indeed, in the studies in which this parameter has been measured, adherence, expressed in a number of different ways, was always highest with transparent dressings. In the study by Aly et al (5) in 50 healthy volunteers and 49 in-patients vs other transparent dressings, gauze and Saran wrap, the lifting index was lowest with Tegaderm TM [0.43 ± 0.99 vs a range from 0.54 ± 1.22 with Saran Wrap up to 1.18 ± 1.23 with another transparent dressing (Uniflex); the difference vs Uniflex was statistically significant (p < 0.05)]. In a study on 407 dressings in 364 children with a peripheral venous catheter, in whom either adhesive tape (n=212) or a transparent dressing (Tegaderm TM ) (n=195) was used, connections were more firm and the dressing was more secure with Tegaderm TM than with the tape throughout the 96 hours observation period (18). The difference was significant (p<0.01) after 48 hours in terms of percentage of patients with firm connections (99% vs 93%), percentage of dressings that were lifting (19% vs 25%) and percentage of dressings that required reinforcement (5% vs 12%). In the randomized, controlled trial in 1,259 patients involving 2,088 Teflon catheters described above in the section on infections (6), transparent dressings with Tegaderm TM were well adherent in 89% of sites vs 89-90% with gauze and 85% with a iodophor transparent dressing; the superiority of Tegaderm TM over the latter was statistically significant (p =0.03). In the study in 442 adult patients with a pulmonary artery catheter described in the section on infections (7) 48% of the traditional transparent dressings (Tegaderm TM ) were totally adherent for 5 days vs 44% of high MVTR transparent dressings for 5 days and 44% of gauze dressings for 2 days. In an Italian study by Gobbi (19) in 73 patients allocated to receive either a gauze dressing or a transparent dressing (Tegaderm TM ), the nurses were asked to provide a full assessment of the dressings from their point of view. Adhesion of Tegaderm TM was considered excellent in 57.5% and good in 42.5%, whereas adhesion of the gauze dressing was considered good in 27.5% of cases, fair in 62% and poor in 10.5%, but never excellent. The catheter was kept firmly in place in all cases by the transparent dressing, the support never being judged as less than good, whereas the gauze dressing kept the catheter firmly in place only in 36.1% of cases; the support was considered to be only fair in 64.2%. In another study a transparent dressing releasing silver ions resulted to be well secured to the catheter in a higher proportion of patients than the traditional transparent dressing (85.7% Arglaes TM vs 70.2% Tegaderm TM ) (17). Ease of application The two factors that contribute to prolonging nursing time dedicated to catheter insertion site dressing are the frequency of replacements and the ease of use. Transparent dressings are replaced less frequently than other dressings, but this advantage could be offset by difficulties in their application. This issue has been addressed in few studies. The comparison with the transparent dressing containing silver ions showed that application of the traditional transparent dressing, such as Tegaderm TM, was never difficult, whereas the application of the novel product was difficult in 17.6% of cases; however, these results are not very reliable considering the small sample size (n=31) (17). In the study by Gobbi (19), in which the nurses were asked to provide a full assessment of the dressings in 73 patients, ease of application of the transparent dressing was considered to be excellent in 94% of cases and good in the remaining 6%, versus only 10% and 66.6% with the gauze dressing, respectively. 72

5 Gallieni TABLE I - LOCAL ADVERSE REACTIONS TO A CONVENTIONAL TRANSPARENT DRESSING (TEGADERM ) AND OTHER KINDS OF DRESSING OBSERVED IN 4 CLINICAL TRIALS (5-7, 15) Local symptom Conventional Gauze/tape Other transparent dressing transparent dressings Erythema 6-18% 14-15% 21% Itching 8% 4-12% 5-16% Pain 12-18% 12-17% 10-21% Tenderness 13-41% 13-46% 23-41% TABLE II - ANALYSIS OF THE COSTS INVOLVED IN THE USE OF TRADITIONAL DRESSINGS, ABSORBING WOUND PADS (VECA-C ) AND TRANSPARENT DRESSINGS (TEGADERM ) FOR CATHETER INSERTION SITES Item Traditional Absorbing pad dressing Transparent dressing dressing (Veca-C ) (Tegaderm ) (3 x catheter) (2 x catheter) (1 x catheter) Cost of dressing units 93 cents 1.12 euro 52 cents Cost of additional material 75 cents 50 cents 25 cents (gloves, ether, disinfectant) Total cost of material per 1.68 euro 1.62 euro 77 cents single catheter Annual cost of material 18,407 euro 17,725 euro 8,408 euro (for 11,000 catheters) Cost of nursing time 6.80 euro 3.15 euro 1.68 euro Assumptions: Min. hourly rate: 8.78 euro replacement dry gauze:15 min replacement of absorption pad and Tegaderm: 10 min monitoring of insertion site: 0.5 min Total cost per catheter 8.48 euro 4.77 euro 2.45 euro Annual cost for dressings 93,260 euro 52,334 euro 26,922 euro for 11,000 catheters (adapted from ref. no. 19) Tolerability at site of application No serious or severe local reactions to traditional transparent dressings have been reported in the literature. Local tolerability has been specifically compared among different types of dressing in a few studies (Tab. I). No significant differences emerged among them in terms of proportions of patients reporting the various symptoms upon removal of the dressing. Cost effectiveness The above-mentioned advantages of fewer replacements and ease of use should result in lower staff costs in terms of less time dedicated to catheter insertion site dressings. However, the higher price of transparent dressings could offset this advantage. Cost calculations have been made in studies using the transparent dressing Tegaderm TM in Canada and in Italy. 73

6 Transparent film dressings for intravascular catheter exit-site The Canadian study (20) was performed in 58 hemodialysis patients randomized to receive either dry gauze replaced 3 times a week or a modified transparent dressing (Tegaderm IV TM ) replaced every 7 days at the insertion site of a tunneled dialysis central intravenous catheter. Notwithstanding the higher unit cost of Tegaderm TM, the lower number of replacements made its use more effective. The lower frequency of dressing changes and greater ease of use resulted in reduced nursing time requirements in the Tegaderm TM group, expressed as lower weekly nursing cost ($10.83 vs $24.88). Even taking additional unscheduled Tegaderm TM dressing changes into consideration, the total cost for Tegaderm TM per patient per week was lower by about 38% ($4.72 vs $7.60 Canadian dollars). The Italian study by Gobbi (19) in 73 patients with an intravenous catheter inserted either in a surgical unit, in the operating theater or in a unit of internal medicine included cost calculations related to three types of dressings: gauze + sterile tape, changed three times during the life-time of the catheter, VECA-C TM sterile dressing (designed for use with IV catheters, it has an absorbing wound pad to keep the catheter insertion site dry) changed twice during the life-time of the catheter, and a transparent dressing (Tegaderm TM ) that remained in place for the life-time of the catheter. The parameter chosen was the cost per annual consumption of catheters in the hospital (11,000 catheters/year). Although the price of the material for the gauze dressing and for the VECA-C TM dressing was only 60% of the price of the transparent dressing, the difference in frequency of replacement made the total cost of the material involved per 11,000 catheters more than twice as expensive for the traditional dressing and the VECA-C TM dressing than for the transparent dressing. Due to the difference in dressing change frequency the cost of nursing time using the traditional dressing was more than twice as high as the cost of nursing time with the VECA-C TM dressing and more than 4 times as high as the cost of nursing time with the transparent dressing. Overall, the annual cost of gauze dressings for catheter insertion sites was nearly twice the annual cost of the VECA-C TM dressing and approximately 3.5 times the annual cost of the transparent dressing (Tab. II). Another interesting economic consideration was proposed by Rasero et al (11). As stated above, they studied different time interval protocols for dressing changes in bone marrow transplant patients, with a mean hospital stay of 40 days. In patients with a tunneled central venous catheter, increasing the time between dressing changes from 2 days (total 20 changes) to 10 days (4 changes) did not determine an increase in the infection rate but decreased costs from $66 to $15.5 in the 10-days group. Accordingly, total nurse time/patient dedicated to dressing changes decreased from 280 minutes to 56 minutes. CONCLUSIONS Transparent dressings are well tolerated and do not appear to cause an increase in local or systemic infection rates according to the evidence currently published in the literature. They offer the advantages of excellent adhesion, firm support of the catheter, fewer replacements per catheter lifetime and ease of application. The last two features result in cost-savings that may even halve the annual cost for catheter insertion site dressings. ACKNOWLEDGEMENTS I thank Dr. Jennifer Hartwig, MD for her professional help in writing the manuscript Address for correspondence: Maurizio Gallieni, MD Renal Unit Azienda Ospedaliera San Paolo Via di Rudinì, Milano - Italy maurizio.gallieni@fastwebnet.it 74

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