Indications and contraindications for NPWT 

Contraindications:

  • Infected wounds:  There is a high risk of severe infection when using NPWT in clearly infected wounds before starting the treatment. If the skin surrounding the wound is inflamed or the wound is smelly, you have to use other ( antibacterial) dressings first before considering using NPWT. We often use gauze soaked in povidone-iodine some days before starting NPWT treatment to reduce the bacterial burden of the wound if we are unsure. A  sensible rule of thumb is: if you are uncertain whether the wound is ready for NPWT, it probably is not.

  • Wounds with a lot of necrosis:  NPWT can deal with some superficial necrosis, but it is not a debridement tool. Using NPWT in wounds with much dead tissue is not only ineffective, but it can also be dangerous. There is a significant risk of infection if we attempt placing NPWT on a necrotic wound! If you have access to an NPWT that can provide irrigation, it is possible to use NPWT in cases with some necrotic tissue. In general, we need to debride the wound well before starting with NPWT!

 

  • Wounds with untreated osteomyelitis

  • NPWT is NOT a treatment for osteomyelitis, even if you have access to NPWT with irrigation. If you attempt to use NPWT in a wound that overlies an area of infected bone, there is a high risk of infection complications. You will risk that abscesses can develop around the infected bone, and there is an increased risk of septicemia! This is easy to respect when you know that there is osteomyelitis lurking beneath the wound. Often, however, we may be unaware of a bone infection. Here we have to use common sense- if you can see or palpate exposed bone, you should have a high suspicion of osteomyelitis. Most commonly, we have seen severe complications when NPWT was used in deeper pressure ulcers of the sacrum ( Stage III-IV) where the caregivers were unaware of osteomyelitis. Be very careful when starting NPWT in these patients. Ideally, you should have done an x-ray or even MRI of the sacrum area to rule out severe bone infection. Also, when treating complex diabetic foot ulcers, you need to be vigilant about the possibility of osteomyelitis hiding in the depths of the wound.

  • Wounds in the vicinity of major blood vessels: Prolonged suction close to a blood vessel can cause mechanical damage to the vessel's wall and lead to severe, uncontrollable bleeding. In most types of wounds, we do not need to be too concerned about this. However, you should be careful, especially in deep wounds in the inguinal area, behind the knee joint, or in the armpits.  

 

  • Over fistulas to internal organs: Applying NPWT over fistulas which communicate with internal organs, can cause tissue damage in these organs and can also lead to bleeding. Also other fistulas can be very difficult to treat with NPWT, and this should be left to expert hands. You cannot simply place an NPWT dressing over a fistula and hope that the fistula will heal. To use NPWT successfully in fistulas, you need to place a material or a tube into the fistula. Again, never attempt this unless you know exactly what you are doing! 

  • Over wounds with exposed joints/joint implants: This contraindication is not on lists of contraindications in other publications. This recommendation comes from our extensive experience with NPWT over the past 20 years. If you attempt to salvage a wound complication with NPWT over an exposed joint, especially if that joint contains an orthopedic implant, you will likely cause a disaster. Believe us, we have been there and done that. The risk of causing a severe infection to the joint is huge. The hypothesis is a phenomenon we have named " pooling." With this, we mean that the negative pressure does not penetrate the joint and instead causes an accumulation of fluid in the joint. This leads to an anaerobic environment where bacteria thrive very well. Some may think that it will help to place some tubes into the joint while using NPWT - this does not solve the problem with "pooling." The same applies to NPWT with irrigation- even though you may have designed your NPWT dressing so that the irrigation fluid may actually enter the joint, you cannot be sure that you are irrigating the entire joint and can still experience the pooling phenomena. That said, there may be situations where NPWT with irrigation can be used over widely exposed joints, even when there is orthopedic hardware present - but this has to be left to expert hands under concurrent antibiotic therapy. 

  • Malignant ulcers sår: When tissue cells are exposed to negative pressure, they start to divide more quickly. This also applies to malignant cells. If you try to use NPWT on a malignant wound, you will most likely stimulate the cancer cells to spread more rapidly.  

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Figure 1  All these wounds have in common that they are unsuitable for starting NPWT treatment. All need some debridement and control over the bacterial burden first. Be very careful when using NPWT on such deep pressure ulcers as on the left image. There is a high risk of an osteomyelitis of the sacrum hiding beneath this.

Relative contraindications

 

  • Patients who cannot or do not want to cooperate:  NPWT demands that the patient can monitor the function of the pump. Several times daily, the pump needs to be checked to see if it is still switched on, if the batteries are fully charged or whether the display shows some malfunction. 

  • Especially the bigger pump models are costly and need to be treated with care. Will your patient be able to take care of the pump? In western countries, we have seen examples where drug addicts who had wounds treated with NPWT removed the pumps and sold them on eBay! Using the much cheaper, smaller pump models avoids some of these problems.

  • It is possible to use NPWT in patients with cognitive impairments like dementia, but then you need a good network of helpers around the patient who can regularly monitor the function of the pump. We have had examples where NPWT  was essential to save a patient's limb, but the patient constantly removed the NPWT dressing because of dementia. In these cases, we have often secured the NPWT dressing with plaster of Paris cast, making it impossible for the patient to remove the dressing. 

 

  • If you do not have the logistics for NPWT:  If you are new to the world of NPWT and are thinking of offering this to your patients, it is essential to establish a logistics plan. Whom should the patient contact if something goes wrong with the pump? Are you available 24/7? Are there other colleagues/members of staff who can substitute you? Believe us, when you are using NPWT, things will go wrong. Leakages appear when the patient is moving, tubing gets torn, pumps may behave erratically, or the patient may sabotage the treatment. You can not start using NPWT before you have a plan for how to deal with these situations.  

 

  • Exposed tendon or bone: It is not an absolute contraindication to place an NPWT dressing over exposed tendon or bone, but this should only be done in experienced hands. When the NPWT medium ( gauze or foam) is placed directly over the exposed tendon or bone, it can suck the tissue dry, causing irreversible tissue necrosis. As a rule, you have to put a protective layer over tendons and bones to prevent this. There are some special foams ( white foam) that are moistened in such a way as to prevent the desiccation of sensitive tissues.

  • NPWT can lead to granulation over smaller areas of exposed tendons or bone, but if there is significant exposure, this technique will not work. So again, you really need to know what you are doing when dealing with these difficult cases.  

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Figure 2  An example where NPWT was used to treat an injury to the lower leg with an exposed achilles tendon. The authors state that the image was taken 10 days after starting NPWT. There is excellent granulation tissue formation in most of the wound but not over the tendon. This is an excellent example to illustrate that NPWT will not be able to develop granylation tissue over larger areas of exposed tendon. To deal with this sort of problem you need to employ other techniques in addition to NPWT. If you would like to read more about this case and how the authors dealt with it, you can click on the image above, and it will link you to the original artice on e-plasty.com. copyright: Ohata et al. 2015 eplasty.com

Indications for NPWT 

 

  • Deep wounds where the natural granulation process is expected to take a long time 

 

  • Wounds that have stalled. Here NPWT can be used to " kick-start" the healing process. We often use this technique to "kick-start" venous ulcers. 

 

  • As a temporary coverage while waiting for other modalities. An example of this may be a large pressure ulcer where there is a plan to do a flap reconstruction. While waiting for the flap surgery, it can be a good idea to prepare the wound using NPWT.  

 

  • To prepare the wound bed before a skin transplant. In our experience, using NPWT 3-7 days before a skin transplant significantly increases the take of the graft. 

 

  • After application of a split-thickness skin graft.  

 

  • As a salvage procedure to save a seemingly hopeless situation- for example, an amputation stump that was debrided because of necrosis.  

 

  • As a limb-saving procedure in extensive trauma situations with significant tissue damage (war injuries, traffic accidents). 

 

  • As a temporary closure of the abdomen until final surgery ( "Abdo-vac") 

  • As a postoperative dressing after surgical procedures where there are increased risks of wound dehiscence or infection. This is called incisional NPWT ( iNPWT) and is commonly used in high-risk patients after orthopedic surgery, breast operations, or a cesarian section.  

  • NB! the use of NPWT has become widespread and we occasionally see examples where caregivers sometimes forget that other modalities may lead to faster or better outcomes. Large tissue defects will sometimes benefit more from a plastic surgical reconstruction with a flap rather than using NPWT for several months. When in doubt, always confer with a plastic surgeon to check if they will suggest any other treatment than NPWT. 

Figure 3 An example of a traumatic wound that is quite deep. You will appreciate that the time for this to heal naturally will take several months. Using NPWT here can shorten this time significantly. We would expect to treat this patient for about 3-4 weeks with NPWT and then consider doing a split-thickness skin graft or letting it epithelialze  naturally. 

Figure 4 An amputation stump of the right leg that had developed an infection and extensive necrosis.  There is a large tissue defect, and it is not possible to simply suture this together again.  The patient may face a new amputation higher up on the extremity.  This can be salvaged using NPWT in the right manner.  The expected time frame for NPWT use here is about 3-6 weeks.  

Figure 5 A mixed ulcer ( both venous and arterial) over the ankle area. The ulcer has stalled and seems to get nowhere. You will see a slightly greyish, translucent layer covering the wound bed if you look closely. This may be biofilm and may be the reason why the wound has stalled. We would debride the biofilm sharply and start with a short course of NPWT to " kick-start" the healing process. Note that there is some slight inflammation around the skin edges. This is not unusual for these wounds but is an indicator that we have to follow this closely when using NPWT. If the redness increases while using NPWT stop the treatment and use antibacterial dressings. 

Figure 6  The image above shows a large pressure ulcer ( at least stage III) over the trochanteric region.  This size of ulcer will take forever to heal, and NPWT is indicated here.  Obviously the ulcer will need a thorough debridement before starting with NPWT.  Expected duration of NPWT here is 3-6 weeks,.  Remember to check carefully if there can be an osteomyelitis hiding beneath thsi before starting with NPWT.