A Closer Look At Combination Therapy For Chronic Wounds

Patricia Kim, DPM, and John M. Giurini, DPM

The advent of advanced treatments has made it possible for chronic wounds to benefit from a wide range of combined modalities. With a closer look at the research and an illuminating case study, these authors examine the efficacy of wound dressings, skin substitutes, hyperbaric oxygen therapy and other therapies.

When it comes to diabetic foot wounds, clinicians may use biologic dressings either independently or in combination with other modalities to facilitate swift resolution of the ulceration. While physicians typically choose treatments based upon patient selection, experience and regional preferences, a wide host of therapeutic modalities are available today. These modalities include silver impregnated dressings, platelet-rich plasma (PRP), bioengineered skin substitutes and hyperbaric oxygen therapy (HBOT).

   All wounds begin as acute wounds that ideally progress through the four typical phases of healing: hemostasis, inflammatory, proliferative and healing. Acute wounds heal in an expected timeframe without any disruption to these processes. Wounds become chronic and fail to heal due to a poor molecular environment that is rife with inflammatory cytokines, proteases and low levels of growth factors. Biologic therapies aim to alter the environment in some way in order to restart the normal healing pathway.

   Chronic wounds affect approximately 6 million people in the United States with lower extremity ulcerations being the most common. Due to an increase in adult obesity, the incidence of diabetic foot ulcers is increasing at a rate of 14 percent per year with 84 percent of that subgroup ultimately undergoing amputation.1 Neuropathy, peripheral vascular disease and pressure are the most common factors causing chronic lower extremity ulcers. Signs of chronic wounds include but are not limited to: increasing wound size, necrosis or nonviable tissue, recurrent breakdown and lack of granulation tissue.2

   Inflammatory phase markers, such as macrophages and polymorphonuclear neutrophils, aid in preparing the wound bed for the proliferative phase. However, their extended presence can cause tissue damage. Bacterial biofilms also act as a deterrent to wound healing. Biofilms are cells that attach to surfaces and are embedded in self-produced extracellular matrix.3 This film shows resistance to antibiotics due to inactivation of antimicrobial agents by extracellular polymeric substances, differentiation of cells into resistant dormant cells and a decreased oxygen gradient.

Investigating The Efficacy Of Silver Dressings

Silver containing dressings have been in use for many years to help manage local infection. Silver has a broad spectrum antibacterial range that includes gram-negative, gram-positive (including methicillin resistant Staphylococcus aureus (MRSA)), aerobic, anaerobic yeast and fungi.4 Silver’s antimicrobial effect is due to its inhibition of DNA replication, interference of the respiratory chain in microbial cytochromes and interference of microbial electron transport system components.

   A study utilizing Aquacel Ag (ConvaTec) showed that the silver impregnated dressings were able to decrease bacterial bioburden without any serious adverse events while continuing to promote wound moisture and exudate management.4 Research also shows that silver dressings can potentiate antibiotic therapy by increasing the susceptibility of bacterial walls within biofilms to antibiotics.3 In addition to its antimicrobial properties, silver also has antiseptic as well as anti-inflammatory properties.

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