Negative Pressure Wound Te

J Wound Ostomy Continence Nurs. 2014;41(3):233-237. Published by Lippincott Williams & Wilkins

WOUND CARE

Copyright © 2014 by the Wound, Ostomy and Continence Nurses Society™ J WOCN ■ May/June 2014 233

■ Introduction

The Centers for Disease Control and Prevention 1 defi nes diabetes mellitus as a group of diseases characterized by high levels of blood glucose resulting from defects in insu-lin production, insulin action, or both. The most common type of diabetes is type 2, previously called non–insulin-dependent diabetes mellitus or adult-onset diabetes. The prevalence of diabetes is signifi cant; the American Diabetes Association 2 stated that 25.8 million individuals in the United States had diabetes in 2011, representing 8.3% of the population. The cost of diabetes mellitus was last de-termined to be $174 in 2007, but better diagnostic tools, better health care leading to longevity, and better reporting methodology lead to far greater projected costs per year

Negative Pressure Wound Therapy in the Treatment of Diabetic Foot Ulcers A Systematic Review of the Literature

Alan Guffanti

■ ABSTRACT

Negative pressure wound therapy (NPWT) is an option for management of complex wounds such as diabetic foot ulcers; therefore, the nursing literature from 2000 to 2010 was reviewed for studies comparing clinical outcomes for diabetic foot ulcers treated with NPWT and those treated with standard moist wound therapy (SMWT). PubMed and OVID databases were explored using the following search terms: vacuum-assisted clo-sure, NPWT, diabetic wounds, and standard most wound therapy. Research studies to judge effi cacy were limited to the results from studies of experimental studies with randomized clinical trials on patients with diabetic foot wounds as the inclusion criteria. Four studies were iden-tifi ed that met the established criteria. Despite variations in patient population, methodology, and additional outcome variables studied, NPWT systems were shown to be more effective than SMWT with regard to proportion of healed wounds and rate of wound closure. KEY WORDS: diabetic wounds , negative pressure wound therapy , standard moist wound therapy , vacuum-assisted closure .

for the future. It is believed that approximately $1 in $10 health care dollars in 2010 were attributable to diabetes mellitus. Indirect costs include increased factors such as absenteeism, reduced productivity, and lost productive ca-pacity due to disease-associated morbidity and mortality.

Diabetes mellitus is associated with a plethora of co-morbid conditions including diabetic foot ulcers. 3 Diabetic foot ulcers are a major reason for hospitalization and limb loss. 4 Neuropathy is a major contributing factor to the de-velopment of these ulcers; it is associated with chronic hyperglycemia and changes in the microvasculature lead-ing to progressive damage to the sensory fi bers that nor-mally signal impending foot damage, and an increased risk of unperceived foot ulcers. The average lifetime risk of developing a foot ulcer is as high as 25%, 4 and foot ulcers and related complications account for approximately 16% of all hospital admissions and 23% of all hospital days among diabetic patients. 3

Healing of a diabetic foot ulcer involves the well-established processes of infl ammation, granulation tissue formation and epithelialization, and fi nally maturation of the scar tissue to provide stable restoration of skin and tis-sue integrity. 5 Topical therapy for diabetic wounds focuses on standard moist wound therapy (SMWT) as the norma-tive course of treatment, based on a major study in 1962 that defi nitively established that a clean moist, occluded wound healed more rapidly than a wound left open to the air. 6 Thus, moist wound therapy is the standard to which other treatments are compared or supplemented. 7

Negative pressure wound therapy (NPWT) has been described in the literature since the 1940s, but

� Alan Guffanti, MSN-CRNP, Nurse Practitioner, Advanced Vascular Wound Associates, Darby, Pennsylvania. Correspondence: Alan Guffanti, MSN-CRNP, 101 Summit Lane, Apt E1, Bala Cynwyd, PA19004 ( [email protected] ). The author declares no confl icts of interest.

DOI: 10.1097/WON.0000000000000021

Copyright © 2014 Wound, Ostomy and Continence Nurses Society™. Unauthorized reproduction of this article is prohibited.Copyright © 2014 Wound, Ostomy and Continence Nurses Society™. Unauthorized reproduction of this article is prohibited.

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Copyright © 2014 Wound, Ostomy and Continence Nurses Society™. Unauthorized reproduction of this article is prohibited.

234 Guffanti J WOCN ■ May/June 2014

vacuum-assisted closure (VAC) systems (one type of NPWT) has been used in the treatment of open wounds on an anecdotal basis and in small studies since the 1980s. 8 The basic components of VAC devices include an open-cell polymer foam dressing that conforms to the wound bed, a transparent fi lm sheet used to seal the dressing, a plastic drainage tube attached to a collection reservoir and a vacuum pump that provides intermittent or continuous pressure, ranging from − 25 mmHg through − 200 mmHg. 9 The negative pressure causes contraction of the dressing and deformation of the cells in the wound bed, which has been shown to stimulate neo-angiogenesis and granula-tion tissue formation. In addition, the negative pressure provides removal of wound exudate and reduces edema, which promotes perfusion. 9 This type of wound treatment is performed in a variety of health care settings, including acute care, home care, long-term acute care, outpatient, and some long-term care settings, but is always monitored (either directly or indirectly) by a health care provider who checks the wound progress by tracking the removal of fl uid, the size of the wound, progress in granulation tis-sue formation, and who intervenes should there be any adverse effects.

Case studies and small comparative studies have been reported that compare wound healing outcomes for pa-tients managed with NPWT to those managed with SMWT. 10 However, recommendations for changes in rou-tine management of diabetic foot ulcers require demon-strated benefi t across multiple studies with larger numbers of patients, and specifi cally studies involving diabetic foot ulcers. It is also important to consider the cost of treat-ment in comparison to outcomes, since VAC is consider-ably more expensive than SMWT. Nonetheless, VAC therapy may prove to be more cost-effective than SMWT, if VAC therapy provides a signifi cant reduction in healing time and overall resource utilization. This literature review was undertaken to address the following questions: (1) Is NPWT clinically more effective than SMWT for wound healing in patients with a diabetic foot ulcer, (2) is NPWT more effective than SMWT in patients with a diabetic foot ulcer, with regard to promotion of faster wound closure rate, and (3) is NNPWT more effective than SMWT in pa-tients with a diabetic foot ulcer, with regard to safety and reduction in secondary complications?

■ Methods

A review of the major nursing journal databases PubMed and OVID from 2000 to 2010 was completed using the key words “vacuum assisted closure,” “negative pressure wound therapy,” “diabetic wounds,” and “standard moist wound therapy.” Criteria for inclusion in this review included ran-domized clinical trials involving patients with diabetic foot ulcers and which comparing NPWT to SMWT. A total of 6 studies were found, and 4 met inclusion criteria.

■ Results

Patients in all 4 studies had chronic or acute diabetic foot wounds although the severity and precursor condition (par-tial foot amputation) varied. 4 , 7 , 11 , 12 Patient demographics (age, ethnic group, etc) and exclusion criteria varied from study to study. For example, Etoz 11 excluded patients who had arterial insuffi ciency as evidenced by absence of pedal pulses; this was not an exclusion criterion in the other 3 studies. The only exclusion criteria that were consistent for all 4 studies were ulcer malignancy, current treatment with corticosteroids or radiotherapy, underlying osteomyelitis, sepsis, pregnancy, and nursing mothers. 4 , 7 , 11 , 12

Prior to treatment assignment in all 4 studies, wounds were debrided of nonviable tissue. 4 , 7 , 11 , 12 In 3 of the studies, systemic antibiotic therapy was given to all patients for prophylaxis following surgical debridement. 4 , 7 , 11 , 12 Patients were randomly assigned to the experimental intervention (VAC) or SMWT in all studies. No studies were identifi ed in which NPWT techniques other than VAC were used. The amount of continuous negative pressure was − 125 mmHg, according to standard treatment guidelines. Dressing changes varied from every 24 hours to every 48 hours to 3 times per week. 4 , 7 , 11 , 12

Patients in the comparison groups received SMWT. However, variations in SMWT were noted. Patients in the Etoz study received traditional moist saline dressings changed twice a day, 11 while participants in the study by Blume and colleagues 7 received advanced dressings (pre-dominantly hydrogels and alginates) according to guide-lines published by the Wound, Ostomy and Continence Nurses Society and institutional protocols. Comparison group patients in the Armstrong and colleagues 4 study also were managed with advanced wound dressings (algi-nates, hydrocolloids, foams, or hydrogels); the attending clinician selected the specifi c dressing based on standard-ized guidelines and an individualized assessment of wound status. In the study by Sepulveda and colleagues, 12 the specifi c dressing was chosen according to the satura-tion of the secondary bandage. If the bandage presented a rate of saturation lower than 50%, the wound was dressed with a hydrocolloid gel, tulle (woven gauze) impregnated with a petrolatum emulsion, and a bandage. In contrast, if the saturation of the dressing was greater than 50%, the wound was covered with an alginate and a bandage.

Question 1 : Is NPWT more effective than SMWT for wound healing in patients with a diabetic foot ulcer?

The evidence from these studies suggests that NPWT using a VAC system promotes healing of diabetic foot ul-cers, and in some cases, complete reepithelialization. 4 , 7 , 11 , 12 In the study by Blume and colleagues, 7 the proportion of ulcers with complete closure was signifi cantly greater ( P = .007) for patients receiving NPWT as compared to SMWT. Similarly, in the study by Armstrong and colleagues, 4 a higher percentage of patients healed with



J WOCN ■ Volume 41/Number 3 Guffanti 235

NPWT than with the control treatment, 56% versus 39% ( P = .040). Etoz 11 also observed a signifi cant difference in the number of days required for complete or near com-plete granulation of the wound bed without any infection, 11.25 days for patients receiving NPWT and 15.7 days for those receiving SMWT ( P = .05). In the study by Sepulveda and colleagues, 12 90% granulation took 18.6 days for pa-tients managed with NPWT versus 32.3 days for patients managed with SMWT ( P = .007).

The endpoints were similar in all studies. In the Blume 7 study, the primary endpoint was complete ulcer closure, defi ned as 100% reepithelialization. Sepulveda and col-leagues 12 defi ned the endpoint as 90% granulation, and although Etoz did not defi ne the endpoint defi nitely by complete granulation, he noted that the criteria for the end point was no sign of infl ammation and readiness for surgical closure almost complete granulation with no signs of infl ammation. 11 However, not all patients in these studies reached the treatment endpoints; this was particu-larly true of the patients managed with SMWT. In the Armstrong and colleagues, 4 study patients were treated until wounds were healed or until completion of the 112-day period of active treatment.

Considered collectively evidence from these 4 studies suggests that NPWT is clinically more effective than SMWT for wound healing in patients with a diabetic foot ulcer. Specifi cally, more patients experienced wound im-provement or complete wound closure when managed with NPWT as opposed to SMWT. 4 , 7 , 11 , 12

Question 2 : Is NPWT more effective than SMWT in patients with a diabetic foot ulcer, with regard to promotion of faster wound closure rate?

It has been reported that NPWT decreases bacterial colonization and interstitial edema. It also increases capil-lary blood fl ow and removes fl uid from the wound, which is hypothesized to promote rapid formation of granula-tion tissue required for wound closure. Furthermore, NPWT reduces wound surface area by the traction force of negative pressure and increases mitotic activity among cells responsible for collagen synthesis and epithelial resurfacing. 9

Etoz 11 measured wound surface area every 48 hours in patients in both the treatment and comparison groups; wound therapy was continued until the wound bed was almost completely granulated and there was no sign of infl ammation. Before treatment, the mean wound surface area was not signifi cantly different between the experi-mental and control groups. However, within 1 week there was an increased amount of granulation tissue and a de-creased amount of nonviable tissue among wounds in the NPWT group. At study endpoint, the mean wound surface area decreased 20.4 cm 2 (range, 88.6-109.0 cm 2 ) in the NPWT group versus a men decrease of 9.5 cm 2 (range, 85.3-94.8 cm 2 ) in the control group; this difference was statistically signifi cant ( P = .032).

In the study by Armstrong and colleagues, 4 the rate of wound healing, based on the time to complete closure, was faster in the NPWT group than in the control group ( P = .005), and the rate of granulation tissue formation, based on the time to 76% to 100% formation in the wound bed, was faster in the NPWT group than in the control group ( P = .002).

The reduction in wound surface area over a defi ned period of time refl ects the rate at which the ulcer is heal-ing. Though not reaching complete closure, Blume and colleagues 7 reported that the surface area of the wounds in the NPWT group was smaller than wounds in the SMWT group ( P = .032). 7 A signifi cant difference in size on day 28 (change of 4.32 cm 2 vs 2.53 cm 2 , P = .021) was also noted and the time to 75% closure was signifi cant (54 vs 84 days) ( P = .014). In summary, the data from these studies sug-gest that NPWT using a VAC system promotes more rapid closure of diabetic foot ulcers than SMWT. 4 , 7 , 11 , 12

Question 3 : Is NPWT more effective than SMWT in patients with a diabetic foot ulcer, with regard to safety and reduc-tion in secondary complications?

Secondary complications associated with diabetic foot ulcers vary, but most commonly involve various infec-tious complications and wound deterioration resulting in amputation. Wound complications in the studies reviewed were typical for diabetic foot ulcers and included wound infections, cellulitis, osteomyelitis, edema, and the need for amputation.

Blume and colleagues 7 found signifi cantly fewer sec-ondary amputations for patients assigned to the NPWT treatment group versus those treated with SWMT (4.1% vs 10.2% P < .035). In contrast, Armstrong and colleagues 4 found no signifi cant differences in secondary amputation rates when comparing NPWT and SMWT (3% vs 11%, P = .6). The relative risk ratio (0:225) indicated that pa-tients treated with NPWT were less likely than control pa-tients to undergo secondary amputation. However, this fi nding must be viewed with caution in light of the 95% confi dence interval (0.05-1.1).

Blume and colleagues 7 evaluated differences between MPWT and SMWT groups at 6 months (incidence of wound infections, edema, cellulitis, and osteomyelitis) and found no statistically significant differences. Armstrong’s group 4 also found no signifi cant differences in the frequency and severity of adverse events among the 2 groups (42% vs 54%, P = .875).

Apelqvist and colleagues 13 examined the data collected in the Armstrong 4 study and noted that signifi cantly more surgical procedures including debridement were per-formed in the SMWT group than in the NPWT group (120 vs 43, P < .001). This fi nding suggests that recurrence of nonviable tissue was more likely among the group man-aged with SMWT, which is consistent with the results of Etoz, 11 who reported that the NPWT group had increased granulation tissue and decreased nonviable tissue when



236 Guffanti J WOCN ■ May/June 2014

compared to the SMWT group. Edema of the extremities diminished in patients in both groups, as did the surface area of diabetic foot ulcers ( P = .05). 11

■ Discussion

Findings from these 4 studies suggest that outcomes using NPWT via a VAC system were favorable when compared to the SMWT in the treatment of diabetic foot ulcers. Specifi cally, the data suggest that VAC therapy promotes faster reduction in wound surface area through granula-tion tissue formation and reepithelialization, reduces time to healing, and may reduce the incidence of infectious complications ( Table 1 ).

These data also indicate that NPWT is associated with no more adverse side effects than SMWT. Nevertheless, NPWT should be implemented as one element of a com-prehensive management program that includes effective offl oading of plantar surface ulcers and tight glucose con-trol in addition to local wound care. As noted by all the investigators, surgical debridement is an essential “fi rst step” in local wound care and should be initiated prior to using NPWT. NPWT can then be used either to promote primary wound healing or to prepare a wound for surgical closure.

Further research is needed to address limitations of these studies that do not control for age, sex, race, and type and severity of the diabetic foot wound. Refi ning the demographic variables as well as narrowing the type of diabetic foot wound might lead to better criteria for the use of VAC. Further research is also needed to address re-source utilization and costs that might lead to more in-formed decisions on where and when to use the VAC. Finally areas of investigation should address the effi cacy of NPWT systems other than VAC and should explore situa-tions in which NPWT is and is not likely to be as effective.

KEY POINTS

✔ Evidence from 4 randomized controlled trials suggests that NPWT using a VAC system is more effective than SMWT in promoting the healing of diabetic foot wounds.

✔ Evidence from 4 randomized controlled trials suggests that NPWT using a VAC system is more effective than SMWT in promoting faster healing of diabetic foot wounds.

Recommendations for Clinical Practice

1. NPWT should be considered as one of multiple op-tions in a comprehensive treatment plan for patients with diabetic foot ulcers.

2. The condition of any wound requiring medical man-agement should be comprehensively assessed with re-gard to underlying causes, systemic factors, and con-ditions at the wound in order to develop a plan of care that should be continually reassessed to determine if progress toward healing is being made.

■ Conclusion

Findings from these studies provide evidence that NPWT is safe and effective for management of diabetic foot ul-cers. Nevertheless, NPWT should be implemented as one element of a comprehensive management program that includes effective offl oading of plantar surface ulcers and tight glucose control in addition to local wound care.

TABLE 1.

Summary Results of Studies Reviewed

Author/Participants Intervention ResultsTreatment

NPWTControl SMWT

Armstrong et al 4 162 patients with diabetic foot ulcers

NPWT (n = 77)SMWT (n = 85)

n (%) patients w/complete closure# days to reach 75% granulationn (%) patients w/ 1 or more adverse events

43 (56%)42

40 (52%)

33 (39%)84

46 (54%)

Blume et al 7 342 patients with diabetic foot ulcers

NPWT (n = 169)SMWT (n = 166)

n (%) patients with complete closure# days to 75%-100% ulcer closuren (%) patients w/ secondary amputations

73 (43.2%)56

7 (4%)

48 (28.9%)114

17 (10%)

Etoz 11 24 patients with diabetic foot ulcers NPWT (n = 12)SMwT (n = 12)

length of caredwound surface decrease, cm

11.2320.4

15.759.5

Sepulveda et al 12 24 patients with diabetic foot ulcers

NPWT (n = 12)SMWT (n = 12)

Patients reaching 90% granulation, nNo. of days to reach 90% granulationPatients w/ infection, n

1218.8

0

1132.2

1

Abbreviations: NPWT, negative pressure wound therapy; SMWT, standard moist wound therapy.

■ References 1. Centers for Disease Control and Prevention . 2011 National

Diabetes Fact Sheet . http://www.cdc.gov/diabetes/pubs/estimates11.htm . Published 2011 . Accessed March 25, 2014.



J WOCN ■ Volume 41/Number 3 Guffanti 237

2. American Diabetes Association . Diabetes statistics . http://www.diabetes.org/diabetes-basics/diabetes-statistics/ . Accessed March 25, 2014.

3. Kirby M . Negative wound pressure therapy . Br J Diab Vascul Dis. 2007 ; 7 ( 5 ): 230-234 . DOI: 10.1177/1474651407007005060

4. Armstrong DG , Lawrence DP , Lavery LA . Negative pressure wound therapy after partial diabetic foot amputation: a multi-centre, randomized controlled trial . The Lancet . 2005 ; 366 ( 9498 ): 1704-1710 . DOI: 10.1016/S0140-6736(05)67695-7

5. Lewis S , Heitkember ML , Dirksen SR , Obrien PG , Bucher L . Medical-Surgical Nursing: Assessment and Management of Clinical Problems . St Louis, MO : Mosby Elsevier ; 2007 .

6. Winter GD . Formation of the scab and the rate of epithelializa-tion of superfi cial wounds in the skin of the young domestic pig . Nature . 1962 ; 193 : 293 .

7. Blume PA , Walters J , Payne W , Ayala J , Lantis J . Comparison of negative pressure wound therapy using vacuum-assisted closure with advanced moist wound therapy in the treatment of diabetic foot ulcers: a multicenter randomized controlled trial . Diabetes Care . 2008 ; 31 ( 4 ): 631-636 . DOI: 10.2337/dc07-2196

8. Penny HL , Dyson M , Spinazzola J , Green A , Faretta M , Meloy G . The use of negative-pressure wound therapy with bio-dome dressing technology in the treatment of complex diabetic

wounds . Adv Skin Wound Care . 2010 ; 23 ( 7 ): 305-312 . DOI: 10.1097/01

9. Argenta LC , Morykwas MJ . Vacuum-assisted closure: a new method for wound control and treatment: clinical experience . Ann Plast Surg . 1997 ; 38 ( 6 ): 563-576 .

10. Braakenburg A , Obdeijn MC , Feitz R , van Rooij IAM , van Griethuysen AJ , Klinkenbijl JHG . The clinical effi cacy and cost effectiveness of the vacuum-assisted closure technique in the management of acute and chronic Wounds: a randomized con-trolled trial . Plast Reconstr Surg . 2006 ; 118 ( 2 ): 390-397 . DOI: 10.1097/01

11. Etoz A . Negative pressure wound therapy on diabetic foot ul-cers . Wounds . 2007 ; 19 ( 9 ): 250-254 . http://www.woundsre-search.com/article/7764 .

12. Sepulveda G , Espindola M , Maureira M , et al. Negative-pressure wound therapy versus standard wound dressing in the treat-ment of diabetic foot amputation . Cirugia Espanola . 2009 ; 86 ( 3 ): 171-177 .

13. Apelqvist J , Armstrong DG , Lavery LA , Boulton AJ . Resource utilization and economic costs of care based on a randomized trial of vacuum-assisted closure therapy in the treatment of diabetic foot wounds . Am J Surg . 2008 ; 195 : 782 – 788 . DOI: 10.1016/j.amjsurg.2007.06.023

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