Examining The Role Of NPWT In Limb Salvage

Marie Keplinger, DPM, and John S. Steinberg, DPM

   Diabetic foot ulcerations are a significant public health concern and cause an increasingly heavy demand on our healthcare systems. Diabetic foot infections cause more than 300,000 admissions to hospitals each year, leading to approximately 92,000 amputations.1 The resulting wounds require intensive local wound care and are slow to heal, resulting in prolonged disability and hospitalization.

   The hospitalizations required for effective treatment of diabetic foot ulcerations have become very costly to the healthcare system. When it comes to providing appropriate treatment and wound care products to these patients, there seems to be a constant battle between physicians and healthcare systems.

   Research has shown that using negative pressure wound therapy (NPWT) decreases bacterial colonization and interstitial edema, and increases capillary blood flow with an overall increase in granulation tissue to diabetic foot wounds.2 In addition, NPWT reduces wound surface area by the traction force of negative pressure, which increases mitosis of tissue around the wound.3,4

   With negative pressure wound therapy introduced to the healthcare plan of many patients with diabetic foot ulcerations, both the overall cost to the healthcare system and the morbidity of patients have decreased. While the initial cost of NPWT is frontloaded, researchers have shown that this therapy can decrease the time to healing and decrease hospitalizations for the treatment of diabetic foot ulcerations.

Assessing The Research On NPWT

   Flack and colleagues designed a Markov model to estimate the cost per amputation avoided and the cost per quality-adjusted life year of vacuum assisted closure (VAC) therapy in comparison with both traditional and advanced dressings.5 With this model simulating 1,000 patients over one year, the researchers focused on uninfected ulcers, infected ulcers, infected ulcers post-amputation as well as healed ulcerations, healed post-amputation ulcers, amputation and death. The study included males and females ages 50 to 65 with type 1 or type 2 diabetes mellitus, and only assessed direct costs to the patients.

   This study found improved healing rates with VAC therapy (61 percent versus 59 percent) and an overall lower cost of care ($52,830 versus $61,757) in comparison to more traditional wet to dry dressings and advanced skin substitute dressings.5

   Philbeck and colleagues examined the cost effectiveness of VAC therapy in the home care of Medicare patients.6 This retrospective study compared the costs of stage III and stage IV pressure ulcers treated with NPWT to those of patients who historically received conventional wound care. Patients with 566 pressure ulcers treated with NWPT closed at an average rate of 0.23 cm2 per day in comparison to 0.090 cm2 for the historical control. Using these healing rates, researchers found NPWT-treated wounds were 38 percent less costly to treat than those receiving conventional treatment.

   A pilot study by McCallon and colleagues examined the outcomes in the treatment of postoperative diabetic foot ulcerations.7 Wounds treated with NPWT achieved closure three weeks sooner than those treated with normal saline moist-to-moist dressings twice daily. Wounds treated with conventional dressings exhibited an increase in surface area of 9.5 percent whereas wounds treated with NPWT decreased by 28.4 percent.

   Armstrong and co-workers retrospectively evaluated the outcomes of 31 patients with large diabetic foot wounds before and after NPWT.8 The mean duration of wounds before NPWT was 25.4 weeks. Ninety percent of wounds healed without the need for further bony resection in an average of 8.1 weeks.

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