Expert Advice

F.A.Q.s - Our brief answers to support you

F.A.Q.s

Profit from our experience and read our answers to your questions.

We have collected the most common questions that we are asked with regards to NPWT and answered them. We want you to profit from our collective expertise.
White Foam vs. Black Foam - which to use when?

Black Foam is the first choice of wound dressing for NPWT because it has a very broad spectrum of applications and is very effective in stimulating granulation formation and exudate removal. However, there are some indications where these properties are not wanted, including in sensitive structures which should not dry out (e.g. tendons) or where a rapid granulation is not desired (e.g. hypergranulation). White Foam can also be applied on native vessels, prosthetic grafts, and bones.

Because the structure of White Foam is denser and more stable than that of Black Foam, it is also the better alternative for undermined wounds.

A few articles suggest the use of White Foam in orthopaedics on infected metallic devices, for example, hip and knee prosthesis, with good results (instillation during the procedure).

Author: Csaba Tóth, M.D., PhD., Debrecen, Hungary

When do I End NPWT?

When do I change the therapy? How long NPWT should be used? When do I stop NPWT?

It is very important to understand, that the initiation of NPWT is usually not the initiation of the treatment, and the end of NPWT therapy is never the end of the treatment of the patient and the wound.

NPWT is an integrated part of the wound healing system, where all three basic wound management approaches are used (gauze therapy, moist wound therapy, NPWT), together with systemic treatment of the patient from the holistic view.

As with any other healing system, the cost – effectiveness ratio plays the critical role. In principle, while NPWT induces wound healing, if during each redress a progress in the healing of the wound can be seen, this is considered an indication for continuation of the therapy.

End of the therapy can be identified when one of the following occurs:

1. we reach a healing goal in the patient and in the wound – i.e. a granulated wound bed prepared for split skin grafting, secondary suture, or out-patient moist wound therapy

2. no progress in the wound is seen after 2 dressing changes; consequently a change of pressure level or therapy mode should be undertaken. If after a total of 4-6 dressing changes (or after approximately 2 weeks) no wound healing progress is seen, the therapy should be ended.

3. NPWT becomes inacceptable to the patient due to complications.

Author: Martin Hut’an, MUDr. PhD., Slowakia

What are Contraindications for NPWT?

When NPWT therapy was first introduced, the classic contraindications included:  unexplored fistulas to organs and body cavities, necrotic tissue in the wound, untreated osteomyelitis and malignancy in the wound, and for direct use on organs, vessels and in anti-coagulated patients.

With NPWT being a newly evolving and rapidly developing method of treatment, the contraindications have in turn changed.

1. Regarding fistulas, NPWT proved to be one of the most effective therapy methods for controlling the secretion of fistulas, diversion of fistula content and, sometimes, even closure of the fistula. It is very difficult to call a fistula unexplored, because, by starting treatment the first step is in fact the exploration of the fistula by wound-bed preparation.

2. Necrotic tissue in the wound presents a barrier between the foam and vital tissue, and thus to the very basis of treatment, i.e. the direct contact of the wound bed with filler is not achieved. This is the reason, that during every NPWT dressing initiation or change, the physician should perform wound-bed preparation in terms of necrotic tissue debridement. In some instances, this is not possible (proximity of vessels, other structures), and these can be left for autolytic debridement (when to a limited extent) during the duration of NPWT therapy.

3. One can hardly consider using NPWT in untreated osteomyelitis, because osteomyelitis first requires excochleation and debridement of the bone before an application of NPWT, which is a treatment. It is also difficult to imagine a physician treating a local problem (osteomyelitis) without first initiating systemic therapy (antibiotics). On bones, tendons, vessels and metallic devices, White Foam dressing should be used instead of Black Foam.

4. Malignancy in the wound is a relative contraindication, which is for the physician to decide. It is thought that NPWT may contribute to the spread of malignancy, but this has not been validated. It is hard to imagine not initiating intra-abdominal NPWT in a patient with open abdomen with tertiary peritonitis after anastomotic leakage following low anterior resection for rectal carcinoma, or a patient with open abdomen and tertiary peritonitis after the Hartmann procedure for perforated carcinoma of the sigmoid.

In the case of palliative wound care, NPWT can help to improve the Quality of Life of patients. It counters the three main malignant wound problems: exudation, odor and pain. The stimulation of cell growth is locally very limited. (See also: Riot S et all: Is the use of negative pressure wound therapy for a malignant wound legitimate in a palliative context? "The concept of NPWT ad vitam": A case series. Palliat Med. 2014 Dec 18. pii: 0269216314560009.)

In cases of malignant fistulas or local expansions (i.e. recurrence of rectal carcinoma in perineum after the Miles procedure), NPWT should not be initiated and alternative wound therapy methods should be considered.

5. NPWT should not be applied over blood vessels or organs without the use of non-adherent dressing for protection against erosion. Even with such a precaution, lowering of the pressure should be considered and vigorous supervision applied.

6. Consideration regarding NPWT initiation should be taken in patients with difficult hemostasis or receiving anticoagulation treatment.

The most recent EWMA (European Wound Management Association) position paper on the use of negative pressure indicates that improper and incorrect application and setting in the indicated cases leads to the failure of treatment, whereas the use of NPWT in an off-label indication under rigorous supervision may lead to successful therapy.  We can conclude that one can consider the use of NPWT even in an off-label indication, but only under vigorous monitoring of the patient.

Author: Martin Hut’an, MUDr. PhD., Slowakia

NPWT and Compartment Syndrome - What is the benefit?

The classical treatment of compartment syndrome was fasciotomy and the relief of the affected compartments of the thigh, lower leg, and sometimes of the foot. This often resulted in significant skin dehiscence due to massive soft tissue swelling. The wound was initially usually covered with Epigard or other wound dressings. Often, the process of decongestion took so long that a primary wound closure of the skin was no longer possible. In these cases, a plastic mesh graft or full-thickness skin graft was normally applied. For the patient, this meant a donor site defect and a graft procedure on the recipient site, with the graft not always completely taking. Frequently, new procedures were required. Since the introduction of NPWT to the market, the time between fasciotomy and wound closure has been considerably shortened because of the excellent decongestant properties, such that at present a primary wound closure can be achieved after approximately a week. It eliminates the skin graft and the cosmetic result is much better than with secondary closure. In addition, the donor wound is completely avoided. Due to the positive effects of decongestion by NPWT, this method is now part of the standard procedure in compartment syndrome. It is worth mentioning the rapid process of reducing any edema and the excellent wound-bed conditioning. The handling of the seal is simple, the learning curve is steep and the end result is convincing in all respects for the affected patients.

Author: Dr. med. Rolf Becker, Cologne, Germany

What are the benefits and treatment aims of NPWT in infected endoprotheses?

The standard regimen for infected endoprostheses was to attempt preservation of the prosthesis with the contribution of antibiotic-containing bead chains with primary closure and short intervals with Second-look operations in early infections. For this purpose, all tissue layers had to be re-opened. The surgical times were correspondingly longer and it was more stressful for the patient. In late infection with loosening of the prosthesis, the regimen has not changed.

A two-stage exchange is still the favored, with explantation of the prosthesis, debridement and spacer implantation, and after an infection-free interval, re-implantation of a new prosthesis. Since the introduction of Instillation NPWT, it is now possible to flush early infections by machine. This has significant advantages over conventional methods. Access to the affected joint is achieved quickly. The sponge is removed and the wound will be debrided again.

Samples are an obligatory component of the regimen. These can be taken quickly and without long preparation times. The main advantage of Instillation NPWT is the machine, which can be set in a way that local wound flushing with an antiseptic solution, usually polyhexanide 0.04%, is possible.

The length of exposure to the antiseptic solution varies with instillations and suction time. Overall, the surgical procedure to the patient is greatly reduced. Additional soft tissue damage resulting from constantly opening and closing the wound is avoided. I have successfully treated more than 50 patients using this method in the early stages of infection and can highly recommend it.

A recurrent infection was found in only one case, in which additional super-infected leg ulcers on the ipsilateral leg were present. Depending on the wound depth, a white or a black sponge can be used. It is important to note that after 4 days the foam is changed at regular intervals. Otherwise, an ingrowth of the sponge in the rapidly forming granulation tissue can be observed, especially in black polyurethane (PU).

Wound closure is always successful at the hips. In knee infection, ensure to almost completely adapt the fascial edges, because the infection can very quickly lead to a retraction of the fascial edges, similar to the infected abdomen. It makes sense to use adapting fascia threads.

The classical method often meant excessive wound secretion, as a rule requiring multiple daily dressing changes. When using NPWT, daily dressing changes are completely eliminated. Wound margin assessment is possible at all times through the transparent film.

Overall, NPWT is sufficient and adequate to treat early infections. The surgical procedure times are dramatically reduced compared to the previous standard method. The end result is convincing, with a very good outcome and excellent acceptance by the patient as well as a growing acceptance as a general mainstay of the treatment regimen for infected orthopedic implants.

Author: Dr. med. Rolf Becker, Cologne, Germany

What are possible complications in NPWT?

The following discusses some possible complications in negative-pressure wound therapy (NPWT), but does not take into account any technological defects. Although there are studies available on NPWT, these tend not to primarily focus on adverse events and risk factors in NPWT. However, a systematic review by Vikatmaa et al. (Vikatmaa P, Juutilainen V, Kuukasjarvi P, Malmivaara A. Negative pressure wound therapy: a systematic review on effectiveness and safety. Eur J Vasc Endovasc Surg. 2008;36(4):438–448) considered the safety of NPWT and concluded that that infection, skin irritation, and pain during foam dressing changes were adverse events associated with this treatment.

The United States Federal Drug Administration (FDA) – a government agency that is responsible for protecting the public health by assuring the safety, effectiveness, quality, and security of human and veterinary drugs, vaccines, and other biological products, and medical devices –  received reports of 6 deaths and 77 injuries associated with NPWT during 2008–2009. (US Food and Drug Administration. FDA Preliminary Public Health Notification: Serious Complications Associated with Negative Pressure Wound Therapy Systems; 2009).The most serious complication – bleeding – was the cause of all 6 deaths. The factors that increased the risk of bleeding included vascular grafts, sternal and groin wounds, anticoagulant therapy, and foam-dressing removal. In comparison, infection and foam dressing retention were the most frequently occurring complications. Studies have alerted us to the fact that fermentative gram-negative bacteria (e.g. Pseudomonas aeruginosa) decreased markedly in wounds treated with NPWT whereas Staphylococcus aureus increased, thus the infection rates are not unexpected.

This text is intended to draw attention to deaths and serious complications – as already indicated, mainly through bleeding and infection – linked to the use of NPWT systems and to provide advice on how to reduce the risk of these complications. We should note that these complications are rare. Complications can occur when treating patients with NPWT in healthcare institutions and also in other locations – including the patients’ homes. Indeed, attention must be paid to outpatient use of NPWT; patients and their carers must be well trained in NPWT use and should also be alerted to how to proceed in case of an emergency.

More detailed information on complications related to NPWT can be found at the following link: UPDATE on Serious Complications Associated with Negative Pressure Wound Therapy Systems, issued February 24, 2011.

Author: Lenka Veverková, Associate Professor, MD, PhD, Brno, Czech Republic

How should users of NPWT proceed?

The selection of patients for NPWT must be careful and thorough; familiarizing oneself with the device labeling and instructions is essential. Keep in mind that NPWT systems are contraindicated for certain wound types and that risk factors need to be carefully considered on an individual basis. A trained healthcare professional should monitor the NPWT patient regularly, while the frequency of the monitoring should be decided after a consideration of the patient’s condition, including wound status and its location as well as co-morbidities. Importantly, care providers should be vigilant for potentially life-threatening complications, including bleeding, and take prompt action when such a situation occurs.

Different types of complications can occur: (Risk Factors for Unsuccessful Treatment and Complications With Negative Pressure Wound Therapy Ann-Mari Fagerdahl, RN, Lennart Boström, Johanna Ulfvarson, Carin Ottosson, Wounds. 2012;24(6):168-177)

1) Technological complications

Obtain appropriate training prior to prescribing and using NPWT.

Be aware of complications associated with dressing changes, including infection and bleeding, which can be associated with retained dressing pieces, adherence of new tissue to retained dressing pieces, and removal of tissue during dressing changes; medical staff with a high degree of knowledge and experience is required for the use of NPWT.

a) Physician needs to master the practical use of the whole NPWT system incl. components – practical skills and experience
b) Limited number of units and canisters available at the ward (in case of high exudation)
c) In some cases (e.g. toe amputation), the wound size may be smaller than the size of the port. Here, a special application technique – bridging – has to be used. 
d) The system may leak in anatomically difficult areas (e.g. perineum, toe amputation) See also FAQ how to seal complicated wound geometries.

2) Therapeutic complications

The strongest risk factors associated with unsuccessful treatment were having a pressure ulcer or a positive culture for S. aureus in the wound and bleeding. Patients with insufficient peripheral vascular circulation in the lower extremities had the highest frequency and a non-statistically significant increased risk for both unsuccessful treatment and complication risk.

a) Must be aware of NPWT indications and contraindications
b) Stretched foil – sheer forces result in blister formation
c) Skin maceration in the surroundings of the wound
d) Increased pain during the dressing change
e) In rare cases, NPWT can result in fistula formation (e.g. fragile intestine suture, too high a level of negative pressure applied during the therapy.

Patient risk factors

Factors that increase the risk of harm from NPWT include:

  1. increased risk for bleeding and hemorrhage
  2. anticoagulant or platelet aggregation inhibitor therapy
  3. friable or infected blood vessels (in case of infected wounds, the infections should stop developing)
  4. spinal cord injury
  5. enteric fistulas

Potential complications of NPWT

Rarely, complications may occur which may require discontinuation of NPWT. These may include:

  • pressure necrosis (tissue death) from the tubing 
  • injury to skin around the wound
  • growth of granulation tissue into the foam dressing
  • increased pain initially, due to reduced pressure as the foam collapses
  • contact dermatitis due to the adhesive transparent tape 
  • fistula (tunnel) formation 
More detailed information on complications related to NPWT can be found at the following links:
http://www.medscape.com/viewarticle/766008_6
http://www.fda.gov/MedicalDevices/Safety/AlertsandNotices/ucm244211.htm
http://www.fda.gov/MedicalDevices/Safety/AlertsandNotices/PatientAlerts/ucm190476.htm
http://www.woundsresearch.com/article/risk-factors-unsuccessful-treatment-and-complications-negative-pressure-wound-therapy
http://www.dermnetnz.org/procedures/negative-pressure.html
Where can I find help?
  1.  The best place you can find a helping hand is at the end of your own arm!
  2. Seek support from the staff of the NPWT system manufacturer or distributor
  3. Web pages of the Vivano Network with useful information, best practice
  4. Send a query to the expert panel of the Competence Network http://www.vivanosystem.info/expert_panel.php

Author: Lenka Veverková, Associate Professor, MD, PhD, Brno, Czech Republic

When do I use NPWT in a case of ACS?

Abdominal compartment syndrome (ACS) is defined as a sustained intraabdominal pressure (IAP) >20 mmHg (with or without an abdominal perfusion pressure (APP < 60 mmHg) that is associated with new organ dysfunction/failure. There are many causes that lead to ACS, which is a life-threatening condition.

The main indication for decompressive laparotomy in ACS is when conservative therapy is unsuccessful. The first step in the treatment of intraabdominal hypertony is to decrease the pressure with conservative and/or semiconservative procedures.

The most accepted forms of decompressive laparotomy are open abdomen therapy using a Bogota bag or with open packing. Currently, negative pressure wound therapy (NPWT) is the most preferred surgical method for the treatment of ACS.

NPWT is effective in decreasing the IAP and removing a retroperitoneal and/or intestinal oedema. Additionally, it helps to eliminate the septic exudation from the abdominal cavity. These have a positive effect on renal, cardiac, and respiratory functions.

NPWT is indicated both in primary and secondary ACS. A specific indication is severe acute pancreatitis. In sterile pancreatitis, NPWT is useful for the treatment of the concomitant ACS. In the case of local septic complications, including septic necrosis, NPWT is also effective. In these cases, NPWT can and should be combined with necrosectomy and open bursa packing with the foam.

NPWT has a lower rate of complications, including bleeding, intestinal fistulisation and septic complications, compared to conventional open abdomen therapy.

The primary abdominal wall closure rate is the highest when NPWT is applied. On the basis of these positive effects, NPWT is considered the most effective therapeutic option and the first line method in ACS treatment.

Author: Szolt Szentkereszty, MD, PhD, Debrecen, Hungary

Does NPWT Work in Abdominal Compartment Syndrome?

Decompressive laparotomy has a rapid effect on the elevated IAP. The renal and cardio-respiratory functions improve spectacularly within a short time of NPWT induction.

From clinical experience, NPWT also has a prolonged positive effect on the IAP. Generally, 1–2 weeks (2–5 dressing changes) of NPWT is sufficient for the recovery of IAP/ACS. In a septic abdomen, this may take longer.

In most cases after NPWT treatment, primary closure of the abdominal wall is possible. However, when this is not possible, other closure technics (e.g. Vicryl mesh implantation) can be used.

On the basis of clinical experiences, NPWT is effective in rapidly and significantly decreasing IAP in all forms of ACS. NPWT in ACS is the first line therapy, and it is therefore recommended.

Author: Szolt Szentkereszty, MD, PhD, Debrecen, Hungary

When to Use Intermittent or Continuous Therapy Mode in Open Abdomen?

Generally, the intermittent suction mode during NPWT results in increased tissue granulation and reduced wound size.

When there is the possibility of a high level of fluid removal from the abdomen, the continuous mode is recommended. Use of the intermittent mode in such cases can induce pain or strip the hydrofoam from the skin.

When the goal at the end of the therapy is to prepare the abdominal wall (fascia) for primary closure, induction of granulation is important. During this phase of NPWT, the intermittent suction mode is preferable.

Author: Szolt Szentkereszty, MD, PhD, Debrecen, Hungary

How is NPWT applied in an Open Abdomen?

In ACS with an open abdomen of grades 1-2, possible primary closure is likely. In such cases, NPWT alone without dynamic sutures is sufficient for the treatment. In open abdomen grades 3–4, dynamic sutures are suggested to minimize the size of the wound and the fascial dehiscence.

In all cases of open abdomen when NPWT is applied, a very important part of the therapy is to cover and protect the abdominal organs from direct irritation of the foam and negative pressure. Therefore, the use of a protective layer is a basic part of the treatment to avoid intestinal fistulisations and bleeding.

Author: Szolt Szentkereszty, MD, PhD, Debrecen, Hungary

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