1. Introduction
The term “surgical wound” used in this document refers to a wound created when an incision is made with a scalpel or other sharp cutting device and then closed in the operating room by suture, staple, adhesive tape or glue and resulting in close approximation of the skin edges. It is traditional to cover such wounds with a dressing, which acts as a physical barrier to protect the wound from contamination from the external environment until it becomes impermeable to microorganisms. The dressing can also serve to absorb exudate from the wound and keep it dry. There is a wide variety of wound dressings and the main types are described below in the Table.
TableClassification of dressings suitable for use on primarily closed incisions*
View in own window
| I. Basic wound contact dressings | |
| Ia. Absorbent dressings and surgical absorbents | Absorbent dressings are applied directly to the wound. Surgical absorbents may be used as secondary absorbent layers in the management of heavily-exuding wounds. |
| Ib. Low-adherent wound contact layers | Low-adherent wound contact layers consist mainly of a fine mesh gauze impregnated with moisturizing, antibacterial or bactericidal compounds. They are either non-medicated (for example, paraffin gauze dressing) or medicated (for example, containing povidone iodine or chlorhexidine). These dressings are widely used primarily as interface layers between the wound surface and a secondary absorbent dressing, usually made of cotton gauze, to prevent it from adhering to the wound surface and causing trauma upon removal. As the dressing dries, fibrin from the wound bed causes temporary bonding of the dressing to the wound, thus permitting healing beneath it. |
| II. Advanced dressings | |
| IIa. Vapour-permeable films | Vapour-permeable films are permeable to water vapour and oxygen, but not to water or microorganisms. They are normally transparent. |
| IIb. Hydrocolloid dressings | Hydrocolloid dressings vary significantly in their composition and physical properties. In general, they consist of a self-adhesive gel-forming mass applied to a carrier, such as a thin polyurethane film or a foam sheet. They contain colloidal particles, such as quar, karaya, gelatic, sodium carboxymethylcellulose, gelatin and pectin, in an adhesive mass usually made of polyisobutylene. In their intact state, hydrocolloids are virtually impermeable to water vapour and thus they facilitate wound hydration and promote moist wound healing. By trapping wound exudates, hydrocolloids create a moist environment that softens and lifts dry eschars or causes their autolytic debridement and proteolytic digestion. They favour also granulation tissue formation and re-epithelialization. |
| IIc. Hydrogels or fibrous hydrocolloid dressing | Hydrogels consist of 80–90% water and insoluble cross-linked polymers, such as polyethyleneoxide, polyvinyl pyrollidone, acrylamide or carboxymethylcellulose, with hydrophilic sites that interact with aqueous solutions, absorbing and retaining significant volumes of water. |
| IId. Polyurethane matrix hydrocolloid dressing | Polyurethane matrix hydrocolloid dressings consist of two layers: a polyurethane gel matrix and a waterproof polyurethane top film designed to act as a bacterial barrier. |
| III. Antimicrobial dressings | |
| IIIa. Polyhexametylene biguanide (PHMB) dressing | A commonly used antiseptic. It is used in a variety of products, including wound care dressings, contact lens cleaning solutions, perioperative cleansing products and swimming pool cleaners. |
| IIIb. Silver-impregnated dressing | The extensive coverage that silver provides against bacteria, fungi and viruses, including nosocomial pathogens and methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE), make it a valuable adjunct in the prevention and treatment of infection. Silver has both bactericidal effects via oxidation of the cell membrane and bacteriostatic effects by inhibiting bacterial replication through damage to DNA. |
| IV. Negative-pressure dressings | Primarily designed to prevent exudate collection while simultaneously preventing desiccation of the wound. It has been also claimed that these dressings increase oxygen tension in the wound, decrease bacterial count, increase granulation formation and prevent shear force on the wound surface. |
A Cochrane review2 and its update1 of the effect of dressings for the prevention of surgical site infection (SSI) found no evidence to suggest that one dressing type was better than others.
The United Kingdom (UK) National Institute for Health and Care Excellence (NICE) issued a clinical guideline for SSI prevention and treatment in 2008, which recommends to cover surgical incisions with an appropriate interactive dressing at the end of the procedure3. The 2013 evidence update of the NICE guidelines suggests that no particular dressing type emerges as the most effective in reducing the risk of SSI, although silver nylon dressings may be more effective than gauze. The update also recommends further research to confirm the effectiveness of modern dressing types4. Postoperative care bundles recommend that surgical dressings be kept undisturbed for a minimum of 48 hours after surgery unless leakage occurs. However, there are currently no specific recommendations or guidelines regarding the type of surgical dressing5–7.
The purpose of this review is to investigate the effect of advanced surgical dressings vs. standard dressings for the purpose of preventing SSI.
2. PICO question
In surgical patients, should advanced dressings vs. standard sterile wound dressings be used for the prevention of SSI?
Population: inpatients and outpatients of any age undergoing a surgical operation (any type of procedure)
Intervention: advanced dressings (hydrocolloid, silver-containing, hydroactive or PHMB)
Comparator: standard postoperative dressings
Outcomes: SSI, SSI-attributable mortality
3. Methods
The following databases were searched: Medline (PubMed); Excerpta Medica Database (EMBASE); Cumulative Index to Nursing and Allied Health Literature (CINAHL); the Cochrane Central Register of Controlled Trials (CENTRAL); and the WHO Global Health Library. The time limit for the review was between 1 January 1990 and 21 May 2015. Language was restricted to English, French and Spanish. A comprehensive list of search terms was used, including Medical Subject Headings (MeSH) (Appendix 1).
Two independent reviewers screened titles and abstracts of retrieved references for potentially relevant studies. The full text of all potentially eligible articles was obtained. Two authors independently reviewed the full text articles for eligibility based on inclusion criteria. Duplicate studies were excluded.
Two authors extracted data in a predefined evidence table (Appendix 2) and critically appraised the retrieved studies. Quality was assessed using the Cochrane Collaboration tool8 to assess the risk of bias of randomized controlled trials (RCTs) (Appendix 3). Any disagreements were resolved through discussion or after consultation with the senior author, when necessary.
Meta-analyses of available comparisons were performed using Review Manager v5.39 as appropriate (Appendix 4). Adjusted odds ratios (OR) with 95% confidence intervals (CI) were extracted and pooled for each comparison with a random effects model. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology (GRADE Pro software, http://gradepro.org/)10 was used to assess the quality of the body of retrieved evidence (Appendix 5).
4. Study selection
Flow chart of the study selection process
5. Summary of the findings and quality of the evidence
Ten RCTs11–20 were identified comparing advanced and antimicrobial dressings to standard gauze or absorbent dressings for the prevention of SSI in closed surgical wounds. Included patients were adults undergoing elective orthopaedic, cardiac, sternotomy, vascular, plastic, abdominal and colorectal cancer surgical procedures.
There were variations in the interventions as some studies used hydrocolloid, hydroactive, silver- or PHMB-impregnated dressings. In addition, there were variations among studies in the definition of SSI and the duration of postoperative follow-up.
After careful appraisal of the studies, the following comparisons were performed:
Overall comparison of all advanced dressings vs. standard wound dressings
Hydrocolloid vs. standard wound dressings
Silver-impregnated vs. standard wound dressings
Hydroactive vs. standard wound dressings
PHMB vs. standard wound dressings
1. Overall comparison of all advanced dressings vs. standard wound dressings
The effect of advanced dressings on the SSI risk varied among the 10 RCTs11–20. One study14 reported that advanced dressings may have some effect compared to standard wound dressings. Three studies11,13,15 showed some effect of advanced dressings, but this was not statistically different. Three studies18–20 found that advanced dressings may cause harm, but this effect was not statistically significant. Two studies12,16 had no SSI events in the intervention or the control group.
Meta-analysis of the 10 RCTs (Appendix 4, ) showed that advanced dressings had neither benefit nor harm compared to standard dressings (OR: 0.80; 95% CI: 0.52–1.23). The overall quality of evidence of this comparison was low due to the risk of bias and imprecision (Appendix 5).
2. Hydrocolloid vs. standard wound dressings
Five studies12,16,18–20 evaluated the effect of the use of hydrocolloid dressing compared to standard dressings to reduce SSI. Three studies18–20 showed some effect of advanced dressings, but the effect estimate was not statistically different compared to standard wound dressings. Two studies12,16 had no events in the intervention or the control group.
Meta-analysis of the 5 RCTs (Appendix 4, ) showed that hydrocolloid dressings had neither benefit nor harm in reducing SSI compared to standard dressings (OR, 1.08; 95% CI, 0.51–2.28). The overall quality of evidence of this comparison was very low due to the risk of bias and imprecision (Appendix 5).
3. Silver-impregnated vs. standard wound dressings
Four studies11,13,14,17 assessed the effect of silver-impregnated dressings compared to standard dressings for SSI prevention. One study14 reported that silver-impregnated dressings may have some effect compared to standard wound dressings. Two studies11,13 showed some effect of silver-impregnated dressings, but the effect estimate was not statistically different compared to standard wound dressings. By contrast, one study17 found that silver-impregnated dressings may cause harm, but this effect was not statistically significant.
Meta-analysis of the 4 RCTs (Appendix 4, ) showed that silver-impregnated dressings had neither benefit nor harm compared to standard dressings (OR: 0.67; 95% CI: 0.34–1.30) in reducing SSI. The overall quality of evidence of this comparison was very low due to the risk of bias and imprecision (Appendix 5).
4. Hydroactive vs. standard wound dressings
One of the intervention arms of a study20 evaluated the effect of the use of hydroactive dressings compared to standard wound dressings to reduce SSI. The study showed that the hydroactive dressings do not significantly reduce SSI compared to standard dressings (OR: 1.63; 95% CI: 0.57–4.66; Appendix 4, ). The quality of evidence of this study was very low due to the risk of bias and imprecision (Appendix 5).
5. PHMB vs. standard wound dressings
One study15 examined the effect of PHMB dressings compared to standard dressings for the prevention of SSI. The study showed that PHMB dressings do not significantly reduce SSI compared to standard dressings (OR: 0.20; 95% CI: 0.02–1.76; Appendix 4, ). The quality of evidence of this study was low due to imprecision (Appendix 5).
In conclusion, the retrieved evidence can be summarized as follows:
Overall, a low quality of evidence shows that advanced dressings do not significantly reduce SSI compared to standard wound dressings.
A very low quality of evidence shows that hydrocolloid dressings do not significantly reduce SSI compared to standard dressings.
A very low quality of evidence shows that silver-impregnated dressings do not significantly reduce SSI compared to standard dressings.
A very low quality of evidence shows that hydroactive dressings do not significantly reduce SSI compared to standard dressings.
A low quality of evidence shows that PHMB dressings do not significantly reduce SSI compared to standard dressings.
There are many limitations to this analysis as the number of studies is small with small sample sizes. There are many factors that may contribute to bias in the included studies. For example, the nature of many different types of dressing makes blinding in these trials difficult. In addition, many commercial manufacturers of specialty dressings provide materials or financial support for clinical trials investigating the effects of the product, thus potentially contributing to the risk of bias.
6. Other factors considered in the review
The systematic review team identified the following other factors to be considered.
Potential harms
A potential allergy or skin irritation may develop in some patients, particularly with silver dressings. One study reported that two patients had metallic silver dressings removed due to itching13. This is important to consider in patients who have known allergies to metals or skin conditions. There has been also increased discussion about the possible safety concerns of ionic silver dressings and the transfer of nanoparticles to patients and health care workers21. Another study noted that the toxicity of silver to human cells is considerably less than to bacteria. Unlike antibiotics, resistance to silver is very rare. Instead of targeting a specific cellular process, silver ions directly interact with proteins and other organic molecules and disrupt electrolyte balances. The affinity of silver to multiple microbial molecules and structures further decreases the risks of resistance22.
Values and preferences
There are many factors that may contribute to the preferences of surgeons and/or patients to use particular dressings. Although no difference in SSI prevention was shown in the meta-analysis of 10 RCTs, other outcomes were reported in some studies. Two RCTs included in these analyses assessed patient comfort and reported that hydrocolloid dressings were more comfortable than standard dressings19,20. Another study reported better cosmetic results in patients whose incisions were dressed with hydrocolloid dressings compared to incisions covered with standard dressings, despite no SSI events in either group16.
Resource use
The cost and availability of advanced dressings may be a limitation, especially in low- and middle-income countries (LMICs). The added cost of using hydrogel, hydrocolloid or silver dressings has been investigated by several of the studies included in this review. Two studies reported fewer dressing changes for hydrogel dressings compared to standard dressings12,19. Although the hydrogel dressings were associated with a cost 2–5 times higher than standard dressings, they may be beneficial for patients unable to change dressings or requiring a return to the hospital for subsequent dressing changes19. One study also attributed increased nursing time with standard dressings, which is a consideration for hospitals with a smaller nursing staff. Similarly, another study reported higher costs for hydrocolloid compared to standard dressings20.
Feasibility and equity
In addition to cost, it may also be difficult for some LMICs to acquire and properly use moist or metallic dressings. However, one study reported that hydrocolloid dressings were less complicated to apply18.
7. Key uncertainties and future research priorities
It was emphasized that there are very few large, high-quality trials investigating different types of dressings that evaluated SSI prevention as a primary outcome. Future clinical studies should focus on generating a large sample size and attempt to create a blinded methodology. Well-designed studies conducted in LMICs are needed, as well as in the paediatric population. It was highlighted that there is a special interest in investigating the use of silver-containing dressings in orthopaedic and cardiac surgery with regard to SSI prevention. Assessment of adverse events should be considered in the trials, including the possible effects of silver nanoparticles.
Appendices
Appendix 1. Search terms
Medline (through PubMed)
(((dressing[TIAB] OR hydrocolloi[TIAB] OR alginate[TIAB] OR foam[TIAB] OR bead[TIAB] OR film[TIAB] OR films[TIAB] OR tulle[TIAB] OR gauze[TIAB] OR non-adherent[TIAB] OR non adherent[TIAB] OR alginates OR hydrogels OR bandages*))) AND (((((((dressing OR hydrocolloid OR alginate OR foam OR bead OR film OR films OR tulle OR gauze OR non-adherent OR non adherent) OR (alginates OR hydrogels OR carboxymethylcellulose) OR bandages OR dressings)) AND ((((surgical wound infection) OR surgical wound dehiscence) OR “surgical site”) OR (“surgical wound infection” OR surgical site infection* OR “SSI” OR “SSIs” OR surgical wound infection* OR surgical infection* OR post-operative wound infection* OR postoperative wound infection* OR wound infection* OR ((“preoperative care” OR “preoperative care” OR “pre-operative care” OR “perioperative Care” OR “perioperative care” OR “peri-operative care” OR perioperative OR intraoperative OR “perioperative period” OR “intraoperative period”) AND (“infection” OR infection)))) NOT ((animals) NOT human))
EMBASE
‘non adherent’ OR ‘carboxymethylcellulose’/exp OR carboxymethylcellulose OR dressing OR ‘hydrocolloid’/exp OR hydrocolloid OR ‘alginate’/exp OR alginate OR ‘foam’/exp OR foam OR bead OR ‘film’/exp OR film OR films OR tulle OR gauze OR occlusive AND dressings OR adherent OR ‘non adherent’ OR ‘carboxymethylcellulose’/exp OR carboxymethylcellulose OR dressing OR ‘bandage’/exp OR bandage AND (‘surgical site infection’ OR ‘wound infections’ OR ‘surgical infections’ OR ‘postoperative wound infection’ OR (‘postoperative care’ AND ‘infection’) OR ‘wound dehiscence’) AND [embase]/lim AND [1990–2015]/py
CINAHL
((dressing OR hydrocolloid OR alginate OR foam OR bead OR film OR films OR tulle OR gauze OR non-adherent OR non adherent) OR (alginates OR hydrogels OR carboxymethylcellulose) OR bandages OR dressings)) AND ((((surgical wound infection) OR surgical wound dehiscence) OR “surgical site”) OR (“surgical wound infection” OR surgical site infection* OR “SSI” OR “SSIs” OR surgical wound infection* OR surgical infection* OR postoperative wound infection* OR postoperative wound infection* OR wound infection* OR ((“preoperative care” OR “preoperative care” OR “pre-operative care” OR “perioperative care” OR “perioperative care” OR “peri-operative care” OR perioperative OR intraoperative OR “perioperative period” OR “intraoperative period”) AND (“infection” OR infection))))
Cochrane CENTRAL
(“wound infection” or “surgical wound infection”) AND “dressings”
WHO Global Health Library
((SSI) OR (surgical site infection) OR (surgical site infections) OR (wound infection) OR (wound infections) OR (postoperative wound infection))
- TIAB:
title-abstract
Appendix 3. Risk of bias assessment of the included studies
View in own window
| RCT, author, year, reference | Sequence generation | Allocation concealment | Participants and personnel blinded | Outcome assessors blinded | Incomplete outcome data | Selective outcome reporting | Other sources of bias |
|---|
| Biffi, 201211 | LOW | LOW | LOW | LOW | LOW | LOW | UNCLEAR* |
| Burke, 201212 | LOW | UNCLEAR | UNCLEAR | UNCLEAR | LOW | UNCLEAR | LOW |
| Dickinson-Jennings, 201513 | LOW | UNCLEAR | HIGH | HIGH | UNCLEAR | LOW | UNCLEAR* |
| Krieger, 201114 | LOW | LOW | HIGH | UNCLEAR | LOW | LOW | UNCLEAR* |
| Martin-Trapero, 201215 | LOW | LOW | LOW | UNCLEAR | LOW | LOW | LOW |
| Michie, 199416 | LOW | UNCLEAR | UNCLEAR | UNCLEAR | LOW | LOW | UNCLEAR* |
| Ozaki, 201517 | LOW | UNCLEAR | UNCLEAR | UNCLEAR | LOW | LOW | UNCLEAR* |
| Shinohara, 200818 | UNCLEAR | LOW | UNCLEAR | UNCLEAR | LOW | LOW | UNCLEAR |
| Vogt, 200719 | LOW | LOW | UNCLEAR | UNCLEAR | UNCLEAR | LOW | LOW* |
| Wynne, 200420 | LOW | LOW | HIGH | HIGH | LOW | LOW | UNCLEAR |
- *
Financial support, compensation or products given to research group from dressing manufacturer.
RCT: randomized controlled trial
References
- 1.
Dumville
JC, Gray
TA, Walter
CJ, Sharp
CA, Page
T. Dressings for the prevention of surgical site infection. Cochrane Database Syst Rev. 2014;(9):CD003091. [
PubMed: 25178020]
- 2.
Dumville
JC, Walter
CJ, Sharp
CA, Page
T. Dressings for the prevention of surgical site infection. Cochrane Database Syst Rev. 2011:(9);CD003091. [
PubMed: 21735390]
- 3.
Leaper
D, Burman-Roy
S, Palanca
A, Cullen
K, Worster
D, Gautam-Aitken
E, et al. Prevention and treatment of surgical site infection: summary of NICE guidance. BMJ. 2008;337. [
PubMed: 18957455]
- 4.
- 5.
- 6.
Owens
P, McHugh
S, Clarke-Moloney
M, et al. Improving surgical site infection prevention practices through a multifaceted educational intervention. Ir Med J. 2015;108:78–81. [
PubMed: 25876299]
- 7.
- 8.
Higgins
JP, Altman
DG, Gotzsche
PC, Juni
P, Moher, Oxman
AD, et al. The Cochrane Collaboration‘s tool for assessing risk of bias in randomised trials. BMJ. 2011;343:d5928. [
PMC free article: PMC3196245] [
PubMed: 22008217]
- 9.
The Nordic Cochrane Centre TCC. Review Manager (RevMan). Version 5.3. Copenhagen: The Cochrane Collaboration; 2014.
- 10.
GRADEpro Guideline Development Tool. Summary of findings tables, health technology assessment and guidelines. GRADE Working Group, Ontario: McMaster University and Evidence Prime Inc.; 2015 (
http://www.gradepro.org, accessed 5 May 2016).
- 11.
Biffi
R, Fattori
L, Bertani
E, Radice
D, Rotmensz
N, Misitano
P, et al. Surgical site infections following colorectal cancer surgery: a randomized prospective trial comparing common and advanced antimicrobial dressing containing ionic silver. World J Surg Oncol. 2012;10:94. [
PMC free article: PMC3407006] [
PubMed: 22621779]
- 12.
Burke
NG, Green
C, McHugh
G, McGolderick
N, Kilcoyne
C, Kenny
P. A prospective randomised study comparing the jubilee dressing method to a standard adhesive dressing for total hip and knee replacements. J Tissue Viability. 2012;21:84–7. [
PubMed: 22658450]
- 13.
Dickinson Jennings
C, Culver Clark
R, Baker
JW. A prospective, randomized controlled trial comparing 3 dressing types following sternotomy. Ostomy Wound Manage. 2015;61:42–9. [
PubMed: 25965091]
- 14.
Krieger
BR, Davis
DM, Sanchez
JE, Mateka
JJ, Nfonsam
VN, Frattini
JC, et al. The use of silver nylon in preventing surgical site infections following colon and rectal surgery. Dis Colon Rectum. 2011;54:1014–9. [
PubMed: 21730792]
- 15.
Martin-Trapero
C, Martin-Torrijos
M, Fernandez-Conde
L, Torrijos-Torrijos
M, Manzano-Martin
E, Pacheco-del Cerro
J, et al. [Surgical site infections. Effectiveness of polyhexamethylene biguanide wound dressings]. Enferm Clin. 2013;23:56–61. [
PubMed: 23528546]
- 16.
Michie
DD, Hugill
JV. Influence of occlusive and impregnated gauze dressings on incisional healing: a prospective, randomized, controlled study. Ann Plast Surg. 1994;32:57–64. [
PubMed: 8141537]
- 17.
Ozaki
CK, Hamdan
AD, Barshes
NR, Wyers
M, Hevelone
ND, Belkin
M, et al. Prospective, randomized, multi-institutional clinical trial of a silver alginate dressing to reduce lower extremity vascular surgery wound complications. J Vasc Surg. 2015;61:419–27
e1. [
PubMed: 25175629]
- 18.
Shinohara
T, Yamashita
Y, Satoh
K, Mikami
K, Yamauchi
Y, Hoshino
S, et al. Prospective evaluation of occlusive hydrocolloid dressing versus conventional gauze dressing regarding the healing effect after abdominal operations: randomized controlled trial. Asian J Surg. 2008;31:1–5. [
PubMed: 18334461]
- 19.
Vogt
KC, Uhlyarik
M, Schroeder
TV. Moist wound healing compared with standard care of treatment of primary closed vascular surgical wounds: a prospective randomized controlled study. Wound Repair Regen. 2007;15:624–7. [
PubMed: 17971007]
- 20.
Wynne
R, Botti
M, Stedman
H, Holsworth
L, Harinos
M, Flavell
O, et al. Effect of three wound dressings on infection, healing comfort, and cost in patients with sternotomy wounds: a randomized trial. Chest. 2004;125:43–9. [
PubMed: 14718419]
- 21.
- 22.
