Topical negative pressure for treating chronic wounds

Negative pressure wound therapy in grade IIIB tibial fractures: fewer infections and fewer flap procedures?

BACKGROUND

Grade IIIB open tibia fractures are devastating injuries. Some clinicians advocate wound closure or stable muscle flap coverage within 72 hours to limit complications such as infection. Negative pressure wound therapy was approved by the FDA in 1997 and has become an adjunct for many surgeons in treating these fractures. Opinions vary regarding the extent to which negative pressure wound therapy contributes to limb salvage. Evidence-based practice guidelines are limited for use of negative pressure wound therapy in Grade IIIB tibia fractures. This systematic literature review of negative pressure wound therapy in Grade IIIB tibia fractures may substantiate current use and guide future studies.

QUESTIONS/PURPOSES

We sought to answer the following: (1) Does the use of negative pressure would therapy compared with gauze dressings lead to fewer infections? (2) Does it allow flap procedures to be performed safely beyond 72 hours without increased infection rates? (3) Is it associated with fewer local or free flap procedures?

METHODS

We conducted a systematic review of six large databases (through September 1, 2013) for studies reporting use of negative pressure wound therapy in Grade IIIB open tibia fractures, including information regarding infection rates and soft tissue reconstruction. The systematic review identified one randomized controlled trial and 12 retrospective studies: four studies compared infection rates between negative pressure wound therapy and gauze dressings, 10 addressed infection rates with extended use, and six reported on flap coverage rates in relation to negative pressure wound therapy use beyond 72 hours. None of the 13 studies was eliminated owing to lack of study quality.

RESULTS

Negative pressure wound therapy showed a decrease in infection rates over rates for gauze dressings in two of four studies (5.4% [two of 35] versus 28% [seven of 25], and 8.4% [14 of 166] versus 20.6% [13 of 63]), an equivalent infection rate in one study (15% [eight of 53] versus 14% [five of 16]), and an increased infection rate in the fourth study (29.5% [23 of 78] versus 8% [two of 25]). In terms of the second question regarding infection rates with negative pressure wound therapy beyond 72 hours, eight of 10 studies concluded there was no increase in infection rates, whereas two of 10 reported an increase in infection rates associated with negative pressure wound therapy use beyond 72 hours. Infection rates varied from 0% to 57% in these 10 studies. Five studies reported low infection rates of 0% to 7% and five reported rates of 27% to 57%. The third question (addressed by six studies) regarded the potential decreased use of a soft tissue flap in patients treated with extended negative pressure wound therapy. Flap rates were reduced by 13% to 60% respectively compared with those of historical controls. Grade IIIB tibia fractures by definition required soft tissue procedures. The patients in these six studies had Grade IIIB tibia fractures after the first débridement. However, after extended negative pressure wound therapy, fewer patients required flaps than grading at the first débridement would have predicted.

CONCLUSIONS

There is an increasing body of data supporting negative pressure wound therapy as an adjunctive modality at all stages of treatment for Grade IIIB tibia fractures. There is an association between decreased infection rates with negative pressure wound therapy compared with gauze dressings. There is evidence to support negative pressure wound therapy beyond 72 hours without increased infection rates and to support a reduction in flap rates with negative pressure wound therapy. However, negative pressure wound therapy use for Grade IIIB tibia fractures requires extensive additional study.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Changes of anabolic processes at the cellular and molecular level in chronic wounds under topical negative pressure can be revealed by transcriptome analysis

Chronic wounds--as defined by the World Union of Wound Healing Societies (WUWHS)--are a considerable worldwide health care expense and impair quality of life. In order for chronic wounds to heal, these wounds must be transformed to a more acute state to begin the healing process. Topical negative pressure (TNP) with reticulated open cell foam (ROCF) is known to promote healing in certain types of chronic wounds. However, little is known about changes at the cellular or molecular level in wounds under various treatments, especially under the physical forces induced to tissue by TNP. In the current study, chronic wound samples were obtained during routine wound debridements prior to treatment and 7-12 days after initiating TNP with a continuous setting at -125 mmHg. Whole genome transcriptome microarray analyses were performed on samples to better understand how TNP with ROCF affects these types of wounds. It was found that more genes were expressed following TNP with ROCF as compared to before therapy and to normal, non-wounded tissue. In this study, we show that TNP with ROCF transforms the chronic wound from its inflammation (non-healing) state into more of a progressive, healing phenotype from a molecular point of view with expression of genes that are commonly associated with these terms.

Initial multi-centre observations upon the effect of a new Topical Negative Pressure device upon patient and clinician experience and the treatment of wounds

Topical Negative Pressure (TNP) has become an accepted intervention in wound healing with a growing body of scientific literature supporting the effectiveness of TNP across a wide variety of wound aetiologies. The range of TNP devices has also increased with perhaps the primary distinction being between those TNP devices that employ gauze or foam as a wound dressing. This study reports preliminary multi-centre observations upon the use of a new gauze based TNP device in the treatment of wounds. Across 3 study centres twenty-nine subjects were recruited to the study with 8 presenting with leg ulcers, 8 with pressure ulcers, 12 with acute or surgical wounds and 1 with a non-healing burn injury. Wounds were then treated with the new TNP therapy for a maximum of 17 days (range 2-17 days). There appeared to be a trend for subjects with leg ulcers to be treated for longer (mean duration 12.9 days) compared to subjects with pressure ulcers (mean duration 6.5 days) or those with surgical wounds (mean duration 8.2 days). Given the relatively short duration of the TNP therapy no wound completely healed although 22/29 (75.9%) showed reductions in surface area per day of treatment with all but 1 pressure ulcer and 1 leg ulcer responding positively to treatment. While not an RCT, this and similar cohort studies may be central to the future selection of TNP devices given the increasing importance of the role of the user interface to reduce the likelihood of incorrect use and sub-optimal outcomes.

Vacuum-assisted closure home care training: a process to link education to improved patient outcomes

Negative pressure wound therapy (NPWT) applies subatmospheric pressure across the wound bed inducing cellular and molecular changes that are beneficial to wound healing. This healing modality may facilitate tissue debridement, infection/inflammation control, and moisture balance; the key components of the wound bed preparation paradigm. To ensure that scientific evidence is diffused into daily clinical practice, we are proposing a knowledge transfer model that articulates an educational plan for the various levels of professional development. The discussion highlights the challenges and potential solutions to integrate NPWT into a seamless continuum of care including a community-based patient care model.

A systematic review of the effectiveness of negative pressure wound therapy in the management of diabetes foot ulcers

Foot ulcers are a common complication in patients with diabetes. Negative pressure wound therapy (NPWT) is a wound care therapy that is being increasingly used in the management of foot ulcers. This article presents a systematic review examining the effectiveness of this therapy. The review question is how effective is NPWT in achieving wound healing in diabetes foot ulcers? The primary outcome for this study was the number of patients achieving complete wound healing (secondary outcomes, other markers of wound healing, adverse events and patient satisfaction). A systematic literature review and tabulative synthesis of randomised controlled trials (RCTs). The review identified four RCTs of weak to moderate quality. Only one study examining NPWT in postamputation wound healing reported data on the primary outcome. These data show a 20% improvement in wound healing [odds ratios = 2.0%, confidence interval (CI) -1.0 to 4.0] and number needed to treat = 6 (CI 4-64). No serious treatment-related complications were reported by any of the studies. One study suggested a reduction in the risk of secondary amputation (absolute risk reduction = 7.9%, CI 0.5-15.43). Studies also reported an increase in granulation and wound-healing rates in patients treated with NPWT therapy. No data on patient satisfaction or experience were reported. While all the studies included in the review indicated that the NPWT therapy is more effective than conventional dressings, the quality of the studies were weak and the nature of the inquiries in terms of outcome and patient selection divergent. There is a strong need for larger trials to assess NPWT therapy in diabetes care with different groups of patients and in relation to different clinical objectives and parameters.

Negative pressure wound therapy: potential publication bias caused by lack of access to unpublished study results data

BACKGROUND

Negative pressure wound therapy (NPWT) is widely applied, although the evidence base is weak. Previous reviews on medical interventions have shown that conclusions based on published data alone may no longer hold after consideration of unpublished data. The main objective of this study was to identify unpublished randomised controlled trials (RCTs) on NPWT within the framework of a systematic review.

METHODS

RCTs comparing NPWT with conventional wound therapy were identified using MEDLINE, EMBASE, CINAHL and The Cochrane Library. Every database was searched from inception to May 2005. The search was updated in December 2006. Reference lists of original articles and systematic reviews, as well as congress proceedings and online trial registers, were screened for clues to unpublished RCTs. Manufacturers of NPWT devices and authors of conference abstracts were contacted and asked to provide study information. Trials were considered nonrandomised if concealment of allocation to treatment groups was classified as "inadequate". The study status was classified as "completed", "discontinued", "ongoing" or "unclear". The publication status of completed or discontinued RCTs was classified as "published" if a full-text paper on final study results (completed trials) or interim results (discontinued trials) was available, and "unpublished" if this was not the case. The type of sponsorship was also noted for all trials.

RESULTS

A total of 28 RCTs referring to at least 2755 planned or analysed patients met the inclusion criteria: 13 RCTs had been completed, 6 had been discontinued, 6 were ongoing, and the status of 3 RCTs was unclear. Full-text papers were available on 30% of patients in the 19 completed or discontinued RCTs (495 analysed patients in 10 published RCTs vs. 1154 planned patients in 9 unpublished RCTs). Most information about conference abstracts and unpublished study information referring to trials that were unpublished at the time these documents were generated was obtained from the manufacturer Kinetic Concepts Inc. (KCI) (19 RCTs), followed by The Cochrane Library (18) and a systematic review (15). We were able to obtain some information on the methods of unpublished RCTs, but results data were either not available or requests for results data were not answered; the results of unpublished RCTs could therefore not be considered in the review. One manufacturer, KCI, sponsored the majority of RCTs (19/28; 68%). The sponsorship of the remaining trials was unclear.

CONCLUSION

Multi-source comprehensive searches identify unpublished RCTs. However, lack of access to unpublished study results data raises doubts about the completeness of the evidence base on NPWT.

Gauze packing of open surgical wounds: empirical or evidence-based practice?

INTRODUCTION

Most surgical wounds are closed primarily, but some are allowed to heal by secondary intention. This usually involves repeated packing and dressing of the raw wound surfaces. Although the long-term care of such wounds has devolved to the care of nurses in the community or out-patient setting, the initial wound dressing or cavity packing is done by the surgeon in the operating theatre. Many surgeons are unaware of the growth of the discipline of wound care, and still use traditional soaked gauze for dressing and packing open surgical wounds and cavities.

RESULTS

This review summarises the some of the modern alternatives available and the evidence--or the lack of it--for their use in both the acute and chronic setting.