By the WoundSource Editors
Chronic wounds pose an ongoing challenge for clinicians, and there needs to be a clearer understanding of the pathophysiology of wound chronicity and treatment modalities available.
By Beth Hawkins Bradley RN, MN, CWON
Negative Pressure Wound Therapy (NPWT) has become standard of care for many wound types. Any clinician who works with NPWT dressings will report that a significant number of wounds will develop a malodor, commonly referred to as a “VAC stink.” In response to malodor, clinicians often opt to give the wound a NPWT holiday, which can delay wound closure. In thi article we will look at factors that contribute to malodor, and interventions that might reduce it.
Malodor is not only associated with NPWT dressings, but it also occurs with other occlusive dressings. Several reasons for malodor have been theorized, but increased bacterial load is generally thought of as the primary factor leading to malodor.
As was emphasized last month, wound beds should be properly prepared prior to beginning NPWT. Slough provides medium for increased bacterial load in a wound. Byproducts of bacterial metabolism include ammonia and sulfur compounds. So removing non-viable tissue prior to beginning NPWT can reduce the risk of malodor.
There have been questions raised about the use of Active Leptospermum Honey (ALH) in conjunction with NPWT to reduce malodor. ALH has properties that may impact bacterial load, thus reducing odor. Edna F. Ganacias-Acuna, MD explains these possible mechanisms for ALH’s effectiveness in reducing malodor in a published case study.1 The glucose component of honey increases osmotic pressure in the wound, attracting fluid into the wound. This fluid helps to soften non-viable tissue to speed debridement. Less non-viable tissue means fewer bacteria in the wound and less odor. Bacteria remaining in the wound prefer to metabolize glucose rather than the body’s cellular components. The byproduct of glucose metabolism is lactic acid, which does not have the odor associated with ammonia and sulfur compounds produced by metabolism of other proteins.2 Honey produces hydrogen peroxide, giving it antimicrobial properties. The use of honey, however, increases the cost of dressings, and may impact the distribution of negative pressure across the wound.
We are, therefore, back to the issue of wound cleansing. The importance of thoroughly flushing and cleansing the wound base and all undermining/tunnels at each dressing change cannot be over-emphasized. In working with clinicians around the country, I find that little effort is given to this important part of wound management. Frequently I notice that the NPWT dressing is removed, the wound is wiped with a moist gauze, and the next NPWT dressing is applied. The impact of this manner of cleansing is questionable.
Irrigation or instillation delivered in conjunction with NPWT is an intervention with documented results in reducing bacterial load in wounds. Some NPWT manufacturers offer options for delivering irrigants either simultaneous to negative pressure, or during an off cycle of the therapy. Some clinicians effect irrigation simultaneously by tunneling an IV tubing into the dressing and delivering fluid in a slow steady stream. Dr. David Armstrong coined the word “chemovac” to define the delivery of various antibiotics and antimicrobials along with NPWT. He has published several articles on the topic. These articles along, with “how-to” videos are readily available on line. Delivering irrigation simultaneous to NPWT not only moves bacteria, but will soften slough to aid in its removal, cleanse debris, and cleanse the foam.
Topical silver used in conjunction with NPWT is a common practice because of its antimicrobial properties. There are many forms of silver available for use with NPWT including silver foam, sound contact layers, powders, alginates and hydrofibers. The costs and properties of each form should be considered before applying these products in order to achieve maximum antimicrobial benefit without jeopardizing delivery of NPWT.
In conclusion, since bacteria are a key causative factor in the development of malodor, reducing bacterial load is an important part of the NPWT plan of care. As with any aspect of local care, a protocol approach will not be as effective as considering each wound individually and using the adjuncts best suited for it.
1. Ganacias-Acuna E. Making Progress with Stalled Wounds: Active leptospermum honey and negative pressure wound therapy for non-healing post-surgical wounds. OW-M. March 2012;10-12.
2. Stotts, N, Bryant R. Acute and Chronic Wounds: Current Management Concepts. 4th ed., St. Louis, Mo:Mosby Elsevier; 2012:272.
About the Author
Beth Hawkins Bradley, RN, MN, CWON is the director of Clinical Operations at Cardinal Health. She has been certified in the specialty of Wound, Ostomy, Continence nursing since 1990.
The views and opinions expressed in this blog are solely those of the author, and do not represent the views of WoundSource, Kestrel Health Information, Inc., its affiliates, or subsidiary companies.