Prevention of surgical site infection (SSI)

Promoting wound healing after surgery by choosing the right dressing

Wound cleansing and the application of adequate phase-oriented wound dressings are an important line of defence against surgical site infections (SSI), a serious complication which affects millions of patients every year. Dressings not only act as a physical barrier to avoid wound contamination but can actively support the healing process.

It is hard to find something more vital to mankind than healing and dressing a wound – a medical art that dates back to ancient times: In one of the oldest medical texts, a clay tablet dating back to 2200 BC, wound dressing – “making the plasters” – is described as one of the “three healing gestures,” together with washing wounds and bandaging them1. Our ancestors used mixtures of mud or clay, plants and herbs to protect wounds and absorb exudates. Oil was a key ingredient in these plasters, preventing them from sticking to the wound and slowing down bacterial growth. Now, more than four millennia later, we use more advanced dressing materials, but the goal remains the same: to make wounds heal fast, to avoid infections, and if they should occur, to manage them, especially after surgery.

However, even with great advances in modern medicine, the most common healthcare-associated infection (HAI) remains surgical site infections (SSI). Millions of patients worldwide suffer every year from SSI, which threaten their lives, cause longer hospital stays, higher costs and contribute to the spread of antibiotic resistance 2. Infections of surgical wounds can cause severe damage, hindering wound healing and leading to significant mortality and morbidity. Most SSI are caused by bacteria of the skin flora surrounding the surgical incision such as Staphylococcus aureus, methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa3. Therefore, post-operative measures such as appropriate dressing of the surgical site are crucial to support healing and prevent SSIs.

Wound healing: a complex, multi-factor process

When surgeons close surgical incisions, they typically apply a sterile dressing. This material provides a bacterial barrier until physiological re-epithelisation occurs. The wound dressing is usually left in place for 24 to 48 hours unless significant drainage or bleeding from the site occurs4. Overall, this early post-operative phase is critical for wound healing, which is a highly regulated process and requires the close interaction of many factors such as cytokines, growth factors, blood and the extracellular matrix to restore injured skin5.

As soon as a wound is formed, the body reacts. Platelets activate, coagulation starts and a blood clot forms. At the same time, inflammatory mediators are released, blood flow increases and phagocytic white blood cells such as neutrophils and macrophages migrate to the wound site. Those cells are crucial to neutralise bacteria and eliminate necrotic tissue. After the inflammatory phase, the skin starts to rebuild, granulation tissue fills the wound and new blood vessels are formed. It is during this proliferation phase that the wound gradually contracts, and epithelial tissue forms at the edges of the wound. Epithelialisation may be completed in 24 to 48 hours in primary closed wounds or delayed for three to five days in wounds healing by secondary intention. Once the wound is closed, the final maturation phase starts, and collagen is remodelled to give the tissue its tensile strength6. Acute wounds go through these three physiological stages and usually heal within four weeks. But when the healing process does not run smoothly and stalls in one phase, acute wounds progress to a chronic state. Factors as increased levels of inflammatory mediators, infections, biofilm, hypoxia and poor nutrition can negatively influence wound healing and lead to chronic wounds, which can be difficult to treat7. Recognising and treating these factors is key to avoid the disruption of the healing process and the evolution of acute wounds into chronic ones.

Modern surgical wound dressings interact with the healing process

Based on the wound type, choosing a surgical site dressing with ideal characteristics for barrier protection is a priority for avoiding SSI. However, there are no standardised recommendations on the best type of post-surgical dressing type8. Today, there are more than 3000 types of dressings available in the market, offering surgeons the possibility of making the best choice of dressing based on the wound type.

Further, modern dressings can do much more than just cover the wound: They can also positively influence the healing process. Therefore, they must meet several requirements9 which include:

  • giving protection against bacterial infection
  • being sterile, non-toxic and non-allergic
  • providing and maintaining a moist environment
  • removing excessive exudate
  • enhancing epidermal migration, promoting angiogenesis and connective tissue synthesis
  • allowing gas exchange between the wound and the environment
  • maintaining appropriate tissue temperature to support blood flow
  • avoiding becoming stuck to the wound and remaining easy to remove after healing
  • providing debridement action to enhance leukocyte migration
  • and easing pain10.

Dressings are usually made of synthetic polymers and can be classified in passive, interactive and bioactive products:

  • Passive products, such as gauze dressings*, are highly permeable, non-occlusive and simply cover the wound.
  • Interactive dressings create a moist environment, are semi-occlusive or occlusive, and actively support wound healing. Films, foam, hydrogel, hydrocolloids and alginates dressing belong to this category. Hydroactive fibre dressings made of cellulose fibres reduce the risk of maceration by efficiently trapping wound exudate, debris and bacteria. Transparent polyurethane film dressings can be used to allow an easy monitoring of surgical wounds while protecting fresh epithelial tissue from external factors such as microbes and liquid.*
  • Bioactive dressings are produced from biocompatible and biodegradable materials such as biocellulose, which are important for the healing process.

Antimicrobial wound dressings can help reduce bacterial colonisation and minimise the incidence of infections11. Growth factors and enzymes are also sometimes included to support repair processes and promote debridement of necrotic tissue, respectively. Mechanical debridement* is also a key component of wound management, as it allows removal of debris, slough, senescent cells and biofilm, preparing the wound bed for reepithelialisation12. In fact, keeping a wound clean and free of debris is crucial to prevent the development of SSI.

In case of highly exuding wounds, superabsorbent wound dressings represent a very valuable option, as they are able to take up excess amounts of fluid. This is particularly important in the management of chronic wounds13. Negative pressure wound therapy (NPWT) also represents a popular treatment modality for both acute and chronic wounds. NPWT systems apply subatmospheric pressure to the wound, improving wound healing14.*

Dressing removal: minimising pain for the patients

When the integrity of the skin barrier is restored, dressings can be removed using clean or aseptic no-touch techniques, depending on the condition of the wound and the patient. During dressing removal, it is mandatory to avoid contact of the wound with infectious material, and hand hygiene guidelines must be followed. It is also important to keep the number of dressing changes as low as possible. Every time a dressing is changed, the wound is exposed to potential pathogens, and the wound healing process slows down. In fact, wound dressings keep the wound at body temperature, ensuring optimal cellular activity for wound healing. After every changing procedure, it takes 3-4 hours for the cells in the wound to resume their tasks15. Reducing the number of dressing changes also results in a possible reduction of skin blistering, periwound skin damage and discomfort for the patient.

During dressing change it is crucial to ease the process for the patients and minimise their discomfort. Explaining the procedure before beginning is as important as involving the patient or family members, if desired. Distraction techniques or the possibility of calling a ’time-out’ during the procedure might also be useful. Effective strategies also include the use of dressings which do not shear the epidermis when removed, the use of warm saline solution to cleanse wounds and the avoidance of cytotoxic solutions which can cause burning16. Using tools which ensure an effective and gentle wound debridement also helps reduce pain for the patient while creating a clean wound bed and preserving intact tissue. It is important to remove slough, devitalised tissue and biofilm during each wound dressing change. Monofilament fibre pads* are very effective tools for mechanical debridement as they are pain- and trauma-free for patients and have therefore a positive influence on compliance17.

Effective prevention of wound infections requires an evidence-based approach

A structured approach is key for improving the overall management of surgical wounds. The implementation of standardised protocols and the institution of interdisciplinary teams being responsible for managing a patient’s wound all contribute to reducing the risk of SSI18. While national guidelines might differ in some of their recommendations, they underline the importance of adopting evidence-based protocols and surveillance measures in the fight against infections. Moreover, they underline the importance of enhanced education for healthcare workers, patients and caregivers following WHO’s Five Moments for Hand Hygiene 19. Finally, involving patients in their wound care is an effective way to increase compliance. Patients should be familiar with hygienic measures for infection prevention, such as hand disinfection*.

As one national example, the German Commission for Hospital Hygiene and Infection Prevention (KRINKO) recommends leaving the surgical dressing on the wound until wound healing is completed unless there is evidence of a healing disorder20. In another example, the National Institute for Health and Care Excellence (NICE) in the UK recommends covering surgical incisions with an appropriate interactive dressing and using aseptic non-touch techniques for changing or removing dressings. Moreover, both the NICE guidelines and the guidelines of the US Centers for Disease Control and Prevention (CDC)21 advise against the use of topical antimicrobial agents for surgical wounds that are healing by primary intention22.

Dressing removal, dressing change and wound cleansing are necessary steps that need to be optimised in order to ensure unproblematic wound healing after surgery. The choice of the most effective therapies, good communication among all service providers, patients, and families, sharing of clinical expertise and close follow-up can also avoid potential wound healing problems.

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Further information

  1. The History of Wound Care, Shah J. B. , Journal of the American College of Certified Wound Specialists
  2. Global guidelines on the prevention of surgical site infection, WHO
  3. Skin and Soft-Tissue Infections: A Critical Review and the Role of Telavancin in Their Treatment, Cardona A. F. & Wilson S. E. , Clinical Infectious Diseases
  4. SSI Prevention: Crossing Environments of Care, Standardizing Incision Management, Collins S., Infection Control Today
  5. Chronic Wound Healing: A Review of Current Management and Treatments, Han G. & Ceilley R., Advances in Therapy
  6. Overview of Wound Healing and Management, Childs D.R. & Murthy A.S., Surgical Clinics of North America
  7. Wound Healing and Treating Wounds: Differential Diagnosis and Evaluation of Chronic Wounds, Morton L. M. & Phillips T. J., Journal of the American Assoziation of Dermatology
  8. Dressings for the prevention of surgical site infection, Dumville J. C. et al, Cochrane
  9. Wound dressings – a review, Selvaraj D. et al, Biomedicine
  10. Chapter Eight – Wounds and Infection, Percival S. L., Biofilms in Infection Prevention and Control – A Healthcare Handbook
  11. Treatment Strategies for Infected Wounds, Negut I. et al, Molecules
  12. Mechanical Debridement: A Brief Overview, Moore Z., British Journal of Nursing
  13. A superabsorbent polymer-containing wound dressing efficiently sequesters MMPs and inhibits collagenase activity in vitro, Wiegand C. & Hipler U.-C., Journal of Materials Science: Materials in Medicine
  14. Effect of negative pressure wound therapy on wound healing, Huang C. et al, Current Problems in Surgery
  15. Wound dressings for primary and revision total joint arthroplasty, Chowdhry M. & Chen A. F., Annals of Translational Medicine
  16. How to Make Dressing Changes Less Painful, Advances in Skin & Wound Care
  17. Clinical Efficacy of a New Monofilament Fibre-Containing Wound Debridement Product, Bahr S. et al, Journal of Wound Care
  18. The Development and Content Validation of a Multidisciplinary, Evidence-based Wound Infection Prevention and Treatment Guideline, Zakhary S.A. et al, Ostomy Wound Management
  19. About SAVE LIVES: Clean Your Hands, WHO
  20. Prävention postoperativer Wundinfektionen – Empfehlung der Kommission für Krankenhaushygiene und Infektionsprävention (KRINKO) beim Robert Koch-Institut, Bundesgesundheitsblatt
  21. Centers for Disease Control and Prevention Guideline for the Prevention of Surgical Site Infection, 2017, Berríos-Torres S. I. et al, JAMA Surgery
  22. Surgical site infections: prevention and treatment, NICE guideline [NG125]

*Commercial communication

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