NPWT dressing techniques

NPWT is very versatile.  With a bit of improvisation, we can treat almost any area of the body with NPWT.  The biggest challenge may be achieving an airtight seal in anatomical areas with skin folds or in areas with a lot of movement like over joints.  It is usually quite difficult to place a NPWT dressing over toes. 

We present the following techniques in this chapter:

  1. "Ready-to-go" NPWT dressings for superficial wounds

  2. Standard Gauze NPWT

  3. Standard Foam NPWT

  4. Gauze/Foam hybrid NPWT

  5. Gauze or Foam with drain tube

  6. Foam under a PICO NPWT 

  7. Use of protective barrier products

  8. Sandwich technique hand/foot

  9. NPWT boot

  10. Treating two wounds simultaneously with a Y- connector 

  11. Bridging technique

  12. Drain relocation 

  13. Bridging technique with small pumps

  14. Finger NPWT

  15. Abdominal NPWT

  16. NPWT with instillation- dwell: NPWTi-d

  17. NPWT over closed surgical wounds: incisional NPWT ( iNPWT)

  18. Using a Crown around enteric fistulas

"Ready-to-go" NPWT dressings for superficial wounds.

With ready-to-go NPWT dressings, we mean kits containing an airtight dressing that is not cut or changed before applying them to the wound. They are placed on the wound like any other dressing and connected to a NPWT pump. These are usually suitable for wounds up to about 1-1,5 cm in depth. Often these kits are sold with small and handy pumps that are both user friendly and not intimidating for the patient. Most pumps do not have a canister. Instead, the exudate is trapped in the dressing like it would in a regular dressing. Some pumps have small canisters. 

The dressings from some producers resemble regular polyurethane foam dressings. In an event where the pump malfunctions, this may not be a crisis as the dressing will continue to work like a regular dressing would. Also, most of these dressings have a silicone contact layer on the inside of the dressing touching the wound bed. This prevents the dressing from adhering to the woundbed. Also- because the silicone represents a contact barrier layer- these dressings can usually be safely applied over areas of exposed tendon or bone without causing damage to these tissues. 

Even though the pumps are usually quite small they provide adequate suction - some pumps work at -80 mmHg, some up to -125mmHg negative pressure. The kits come with dressings in different shapes and sizes. It is possible to treat quite large wounds with these "ready-to-go" kits. Treating a wound for example 10x15 cm in size is usually not a problem for these small pumps. However, as they only have a small motor, they cannot adapt to leakages aswell as a bigger pump. While beginners may find it much easier starting with this type of NPWT, it is important to understand that they not always are the best solution for some types of wounds. If the wound is deeper than 1-1,5 cm, you will need some kind of wound filler in addition to these dressings. We discuss this technique later on in the chapter. Also, the pumps are single-use only. Some pumps are programmed such that they stop working after 7 or 14 days. Some pumps are programmed to work for 30 days. After this time, the pumps become electronic waste, so there is an environmental aspect to this too. 

 

Several producers have these "ready-to-go" kits available. Probably the best known example is the PICO system by Smith & Nephew. In the video below, the principle of "ready-to-go" NPWT dressings are explained using the PICO NPWT pump system as an example. These types of NPWT dressings work really well on the legs where the surface is flat and it is easy to achieve a good seal. However, with patience and improvisation, it is possible to use these small pump systems almost anywhere. We have even seen them being used in quite large and complex wounds- but that was in expert hands. In the second video, below is an example of a more advanced technique using the PICO on a finger. 

Video 1 Explaining "ready-to-go" NPWT dressings, using Smith & Nephew's PICO system as an example. These kits contain dressings that are simply placed on the wound and connected to a pump. Exudate is collected in the dressing itself. These types of NPWT dressings work well in wounds with a depth of up to 1,5 cm. If the wound is deeper you will need gauze or foam as a filler beneath the dressing. copyright: Smith & Nephew

Video 2 This video by Dr. Arthur Desrosies show how versatile the"ready-to-go" NPWT dressings can be. In the video he demonstrates a technique of applying the PICO NPWT dressing to a finger. Fingers and toes are notoriously difficult to place an airtight NPWT dressing to. copyright: Dr. Arthur Desrosies

Using a gauze or foam filler underneath a "ready-to-go" NPWT dressing

If the wound is deeper than 1,5 cm, you should use a wound filler to ensure that the negative pressure reaches all areas of the wound bed. Always remember the principle: negative pressure will only reach the cells of the wound bed if the wound is in contact with some kind of medium (wound filler) - be it the dressing, gauze, or foam. It is the medium that transmits the negative pressure to the wound. 

You can use either gauze or foam as a wound filler in conjunction with a "ready-to-go" dressing. 

Video 3 This video by Smith & Nephew shows how to apply a PICO NPWT dressing with a foam filler beneath. You can also use gauze as a filler if you do not have foam available. copyright: Smith & Nephew

Standard gauze NPWT 

If the wound bed is very irregular in shape a gauze may be superior to a foam in NPWT, because the gauze will conform betetr to the shape of the wound. If you have few resources and have to improvise with a "homemade" NPWT, gauze may be the only medium available to you. When using NPWT over  a split-thickness skin graft, we also prefer gauze to foam. This is because the foam sometimes can tear at the fragile graft as the foam contracts. Lastly- if the patient has a lot of pain at dressing changes using gauze may help. the gauze will usually adhere less to the woundbed than foam. In commercial kits very often a PHMB impregnated gauze ( Kerlix AMD) is used. This has antibacterial properties and prevents bacteria from thriving too much in the gauze. If you cannot purchase this, regular cotton gauze can also be used. 

The gauze should be premoistened with saline and then squeezed dry with your hand before placing it in the wound. Do not stuff the wound with the gauze and do not overfill it. 

Video 4  A film by Smith & Nephew explaining the principles of gauze as a medium in NPWT. copyright: Smith & Nephew

Standard Foam NPWT

 

Foam as an NPWT medium usually leads to slightly quicker and better granulation tissue than gauze. If the wound bed is not very irregular and the patient does not have much pain during dressing changes, foam should be your first choice as a medium. The foam usually comes in big pieces that are cut to fit the wound. Sometimes several pieces of foam have to be placed into the wound to fill it entirely. Always document in the patient journal how many pieces of foam you placed into the wound. We have ourselves on occasion left behind small pieces of foam and sometimes this has led to an infection!

The foams of different manufacturers are very similar. they are all made of polyurethane foam material but may differ slightly in the size of their pores. In our experience the differences are negligible with respect to treatment outcomes. Some producers have foams impregnated with silver. We use these in wounds where there may be a little more necrosis or if we want to extend the dressing change intervals. In most situations we use regular foams that do not have antibacterial properties. The video by Medela below, gives an excellent introduction to using foam in NPWT and also provides some useful tips and tricks. 

Video 5  A film by Medela explaining the basics of using foam as a medium in NPWT. We strongly suggest you watch the film as it contains several useful tips and tricks. copyright: Medela

Gauze/Foam hybrid technique

When the wound bed is very irregular, it is best to place gauze on this as it conforms better to the wound bed's shape. The reason why we want the medium to be in good contact with the entire woundbed surface is to avoid pooling. By " pooling" we mean that exudate can collect in areas of the wound bed where there is no contact with the NPWT medium. In these "pools" bacteria will thrive which can lead to pus formation here and the risk of an infection. Over this we can place a standard foam. We can ofcoutrse, use gauze to fill an entire wound. This is by no means an inferior method. However, as we have mentioned earlier, foam often leads to faster end better granulation. So if we cover the bottom part of the wound with gauze we can still use foam for the rest of the wound. It is usually enough to only use a thin layer of gauze at the bottom- just enough to cover the irregularities of the woundbed.  

Figure 1 Illustrasjon of the gauze/foam hybrid technique. The gauze covers the irregularities of the wound bed and foam is used in  the rest of the wound. 

Gauze or foam in conjunction with a drain

If there is a tract, tunnel, sinus, or even a fistula connected with the wound we have to place something in these . Failure to do so may lead to infection as fluid easily pools in such canals. We will constantly repeat this throughout the chapter. The negative pressure will only be effective where there is a gauze or foam touching the wound. In areas where the medium is not in contact with the tissue fluid will collect. This fluid will turn into pus as an NPWT is an airtight and anaerobic environment which bacterial love.

 

The problem with narrow tracts also. is that it often is not possible to place gauze or foam into these because they are so narrow. Do not try to stuff gauze or foam in narrow tracts! Not only can you harm the tissue but you may easily end up with foreign material residues within the tract. If you attempt to cut a piece of foam into a small strip and place this into a narrow tract you will most likely tear the bit as your remove it at the next dressing change!

The work-around solution to this is to place a perforated drain in these tracts/sinuses. The perforations have to be all along the drain- not just at the end of the drain. Smith & nephew have a wide range of drains available for this purpose. Some drains have gutters rather than perforations. If you do not have special drains available for this you will have to improvise. You can use a urine catheter for this and cut multiple small holes into the drain. Hold the catheter away from the wound while cutting the holes or you will end up with tiny silicone pieces spread around in your wound. 

Treating fistulas with NPWT is for experts only. The fistula should be explored and you need sound anatomical knowledge to know where the origin of the fistula is. The fistula needs to be probed and sometimes mapped using fistulography. The latter technique involves using a contrast agent that is injected into the fistula while taking images using regular x-ray, CT, or MRI techniques. It is contradicted using NPWT on fistulas where the origin is unknown. It is also contraindicated to use NPWT on fistulas that are connected to internal organs. 

Figure 2 Illustration of how a drain can be incorporated into an NPWT dressing. The drain may be cut and end in the gauze of foam medium. It is even better when the drain is directly connected to the suction tube leading to the pump as shown in the video below. The latter technique can only be used with pumps that have a canister to collect exudate. 

Video 6  A film by Medela explaining the use of a drain tube in an NPWT dressing. The video demonstrates how the drainage tube can be connected directly to the suction tube. As the video shows graphic images of an actual ulcer, it is age-restricted and can only be viewed on youtube. Copyright: Medela

Using protective contact layers

 

There are situations where gauze and especially foam, is contraindicated. Examples are within close proximity to larger blood vessels and on exposed tendon or bone. Often we can still use NPWT in these situations but have to protect these delicate tissues from harm. If a foam exerts direct suction on a major blood vessel this can obviously leed to bleeding. Using foam and even gauze directly on exposed tendon or bone can lead to dessication and necrosis of these tissues.  

As we have discussed in the previous chapter on NPWT tools, white foam is a special pre-moistened foam which is more gentle. This should not be used in close contact with larger blood vessels, but may be used on exposed tendons or exposed bone. Be aware that also white foam can dry out such tissues so you have to evaluate the tissue closely at each dressing change.

Usually it is safest to place a thin contact layer between delicate tissues and any type of foam or gauze. These contact layers are usually made of slicone, rayon or other non-adherent materials. The contact layers are made as a netting, that is, they are perforated as a mesh, allowing fluids to drain through the mesh. We can then place a gauze or foam above this layer. If you are close to larger blood vessels it is safer to use gauze as a medium above the contact layer. Remember that you can also decrease the level of negative pressure. You could for example start off using -60mmHg if you are unsure if the tissues will tolerate the NPWT. In simple, single use pumps you cannot alter the pressure settings. 

When using NPWT to enhance the take of a split-thickness skin graft we routinely use a contact layer on the graft before applying gauze as the NPWT medium above this. 

Some contact layers have antibacterial additives like silver or iododine. These may be a useful when we are concerned about the bacterial load of a wound. Remember however, we should never apply an NPWT dressing to a smelly wound, wounds with a lot of necrosis or apparently infected wounds. 

Figure 3 In situations with exposed tendons/bones and near larger blood vessels, a contact layer should be applied beneath the NPWT medium.  Most contact layers are meshes made of non-adherent silicone, rayon, or other materials.  The perforations in the mesh allow for exudate to travel through the contact layer into the NPWT medium.  Some contact layers have antimicrobial additives like silver or iodine. 

Sandwich techniques for hands and feet

It can be tricky to get an airtight seal around an NPWT dressing on hands and feet. Especially around toes and fingers, it can be frustrating to use NPWT unless you have practiced this and gained some experience. Even if you achieve an airtight seal at first, it is common for leakage to appear within a short time as the patient ambulates or uses their fingers. 

Instead of applying an NPWT dressing on only one toe or a small area of a hand/foot, it is far easier to place the entire hand/foot in an NPWT dressing. Obviously, the patient may feel this is a bit impractical since the hand cannot be used if it is completely wrapped up. But if the wound is severe enough, the positive sides of the NPWT treatment will outweigh the downsides. 

When wrapping an entire hand /foot in an NPWT dressing, it is easiest to use the sandwich method. It is essential to pad between all the fingers/ toes to prevent pressure between the toes and prevent moisture-associated skin damage. You can use gauze, cotton wool, or a foam dressing cut into strips to place between fingers/toes. After this, you apply padding to the rest of the skin to be wrapped up. We usually use 2-3 layers of cotton wool wrap or regular gauze. Do not apply this too tight. We then proceed to cover this with plastic film - it is this film that is applied as a sandwich- see the images below. Since the NPWT goes circumferential around the extremity, it is recommended to start with a lower pressure setting - for example -60mmHg to make sure that the blood circulation is not affected. In our experience, even patients with an ankle-brachial index of below 0,8 tolerate regular pressure settings of between -80-120 mmHg. Still, it is always wise to start with lower pressure settings first. Most patients do not feel any discomfort from a circumferential NPWT wrap  

Figure 4  The sandwich technique is identical for hands and feet application. We start with padding the areas between fingers/ toes with cotton wool strips or other soft material. After this we pad the entire hand/foot. In the bottom right picture some of the fingers are still exposed. This is not a problem but you might aswell cover them aswell.  

Figure 5 After padding the hand/foot, we apply the plastic film in a sandwhich technique. Place the hand/foot on the adhesive side of a plastic sheet, and lay another plastic sheet on the oppsote side. Press the adhesive sides of both sheets together. Cut a hole in the plastic for the connector tube leading to the suction pump. It is best to place this hole quite close to the wound area, otherwise wound exudate will have to travel through a lot of the padding to get to the outside. 

Figure 6 The tube connector is applied to the hole in the plastic film and the pump suction is switched on. After checking for leaks, excess plastic film around the edges can be cut off. We often wrap the dressing in gauze to protect it from accidental perforations.  

Figure 7 Example of another type of sandwich application on a foot using a PICO NPWT dressing. The patient is a child with a third-degree burn wound. The necrotic areas were debrided and covered with a skin transplant. Mepilex Polyurtehane foam pieces were used as padding between the toes. A large PICO dressing was wrapped around the foot and re-inforced with plastic film. Copyright: with kind permission from kinderchirurgie-loerach.de

Figure 8 Another example where a PICO dressing is used as a sandwich dressing. The patient is again a child with third degree burns on a hand. The dead tissue has been debrided and covered with  a full thickness skin graft, Because there also were some second degree burns on the fingers, these were wrapped in silcone contact layer before applying polyurethane padding between the fingers. Again, a large PICO dressing was folded over the hand as a sandwich. This makes a somewhat clumsy dressing but the patient should not use their hand anyway for a few days. And when the "clumsy" dressing ensures a good result, who cares if the dressing is a bit bulky? Copyright: with kind permission from kinderchirurgie-loerach.de

NPWT sleeve 

In some situations, it may be most practical to wrap an entire leg or arm in an NPWT dressing. A situation where this is useful is for example a large venous ulcer where the peri-wound area is also damaged and moist. In these situations it can be difficult to get the plastic film to adhere to the skin or it may loosen prematurely. We also use this technique when there are extensive or multiple wounds on an extemity. When we apply this to the lower extremity we call it a NPWT boot. 

 

Another advantage of this method is that it also supplies compression to the extremity when the suction pumped is turned on. Compression is useful for wound healing in general even when the patient does not have significant edema.    When we use regular compression treatment we usually use a compression pressure of between 20-40 mmHg. How does this compare to the pressures from a circumferential compression dressing? The pump settings are usually minus  80-125mmHg. Will this not be too much compression? That is a good question. When the pump is switched on the dressing presses down on the skin with a significant pressure but remember- there is also a vacuum effect in NPWT. This seems to compensate for the higher pressure.  -80mmHg from a suction pump is not the same as 80 mmHg from a compression bandage. We have very good experiences from using NPWT for compression therapy also. Infact most patients find the compression from a circular NPWT dressing much more comfortable than compression stockings or a compression bandage! However, it is always wise to start a bit carefully- we recommend starting at -60 mmHg negative pressure and increasing this if the patient feels no discomfort. 

When we wrap an entire extremity in a NPWT dressing we have to pad the areas between the toes just as we do when using the sandwhich technique. We place gauze or foam in the wound area and wrap the entire leg or arm with cotton padding. Until recently we had to improvise with large sheets of plastic film to make an airtight seal. We have also used clear plastic bages for this purpose on occasion and sealing it proximally with plastic film. 

Recently a producer has recognized the need for a special sleeve for this purpose. The company Lohman & Rauscher now sell a sleeve that fits well to a leg or an arm making this technique a lot easier. 

Video 7 Lohman & Rauscher have developed a sleeve that makes it easier to apply NPWT to an entire extremity. Before this came on the market, we used regular clear plastic bags for this purpose. Still, because plastic bags usually have a large opening, it was sometimes difficult to achieve a good seal proximally. Also, plastic bags do not allow for any evaporation. These special sleeves are airtight yet allow some evaporation, thus reducing moisture-associated skin damage during NPWT treatment. 

Treating two separate wounds using a Y-connector

If a patient has two separate wounds close to each other, connecting these using a bridge is usually practicable.  If the wounds are far from each other- for example, one wound on each foot, this can easily be managed using a Y connector.  All producers selling NPWT equipment also sell such Y-connectors. If you do not have a product-specific Y-connector available, you can improvise with any Y-connector of the appropriate size for the tubing you use.  Using several y-connectors, you can even treat more than two wounds simultaneously.

Figure 9  Y-connectors allow you to connect two separate wounds on the same patient to one pump. Note that many producers have unique connection  links. If you want to use a universal Y-connector bought from a hardware store you will usually have to cut off the original connectors. 

Bridging technique

With the bridging technique, we build a bridge with the NPWT medium ( foam or gauze) between wounds in close vicinity to each other. We could use a Y-connector to connect these two wounds but when the wounds lie close to each other a bridge is more practical. In other situations we may want to divert the tubing to another anatomical area to avoid pressure injury from the connection plate or the tubes - this type of bridge is called drain-relocation and will be discussed in the next section.  

It is important to build the bridges wide enough. If you only use a very thin section of foam or gauze, this can collapse so that the negative pressure is not transferred properly between the two areas. If there is a lot of exudate we prefer to use foam as a bridge material. Gauze can get clogged with exudate that has high viscosity, but if you use enough gauze this is not usually a problem. 

 

In most cases the bridge between two wounds lies over intact skin. We do not need to exert unnecessary negative pressure on this intact skin. It is therefore common to place a layer of adhesive plastic sheet on the intact skin before placing the bridge on top of this. Place the connecting tube on the wound that has the most exudate, or the largest wound.  

Figure  10  Building a bridge with foam between two separate wounds in close vicinity to each other. It is important to make the bridge wide enough to avoid that the bridge collapses when suction is applied. If the bridge material contracts too much, the negative pressure may not be evenly directed to both wounds. Place the drain connector over the wound with most exudate, or the largest wound. 

Drain relocation

This is a particular type of bridging technique with the aim of moving the drain connection plate and tubes away from areas prone to pressure injury. Even though the connecting plates are quite soft they can nonetheless cause pressure injury. Typical sites where we may need to use drain relocation techniques are the back of the head, sacrum or heel areas. If you are treating an ulcer on the sacrum it may be wise to build a relocation bridge all the way to the front of the abdomen. Having the drain connector/tubes attached to the side of the patient is not good as these areas are pressure prone when the patient is lying on his side. Some producers provide ready made drain relocation kits in different lengths, but you can easily make this yourself using the regular bridging technique. 

Video 8 An example of drain relocation from the sacral area. copyright: Susan Reid/Tycon Express

Video 9 An example of drain relocation using a ready-to-use bridge  In the video, the Granufoam bridge from KCI/3M is demonstrated. In this example, a bridge is connected to a leg ulcer - this is not the most common area to use a bridge as it usually is not a problem to connect the drain tube directly to this part of the leg; however, the video shows the technique involved  copyright 3M/KCI

Figure 11 Two screenshots from videos by KCI which unfortunately are not available anymore. The upper image shows the ready-to-use relocation bridge coming from the back towards the front of the abdomen. The lower image shows a relocation bridge applied to a foot ulcer. copyright both images KCI/3M

NPWT on fingers

Finger injuries often respond very well to NPWT because fingers have excellent arterial supply. The most common finger injuries are at the fingers' ends, where the patient can sustain some tissue loss. Using NPWT, it is possible to repair that tissue loss by building up granulation tissue using NPWT.

 

If a patient has an isolated finger injury, it is tempting to apply an NPWT to only that finger. In that way, we can avoid immobilizing the entire hand in a bulky NPWT dressing. However, placing an NPWT on a single finger is no easy task. We have used NPWT extensively for the last 20 years and count ourselves as being quite good at improvising. Still, currently, we have no easy solution for the isolated finger NPWT dressing. We have tried tubular dressings with a hose connected, we have used silicone or other sealants to close any possible leaks, and yet often, there is leakage after a few hours or days. 

Video 2 in this chapter shows a technique where a PICO dressing is wrapped around a single finger in a sandwich technique. This is one solution, but it makes quite a bulky dressing.

After some trial and error, we find that the most elegant solution is using a special finger dressing from Polymem.  This comes in several sizes and is specially designed for fitting a finger. It is a polyurethane foam dressing that is airtight yet allows for evaporation. The foam is the NPWT- you do not need to use gauze or other foam on the wound. Polymem usually does not adhere to the wound and is, in most cases, pain-free at dressing changes. You will have to use plastic film and maybe some sealant at the upper end of the finger dressing. Before applying the plastic film, you have to cut a hole in the finger dressing and place a suction tube there. The tricky part of this technique is getting a good seal around the tubing. We have used the PICO pump in these situations. Incidentally, the Polymem finger dressing is, in our opinion, the best finger dressing available today - also when not using it with NPWT. In our experience, it works significantly better than all other finger dressings we have tried. Polymem contains some active ingredients- a surfactant for cleansing and glycerin for optimal moisture level. In addition, it has an analgesic effect. Most of our patients with finger injuries have surprisingly little pain when using Polymem finger dressings. 

Figure 12 We hope that a company will soon develop a commercially available NPWT finger dressing. Until then, we have to improvise. We have had good results using Polymem finger dressings. Cut a hole in the dressing ( as far away from the skin damage as possible otherwise, exudate will enter the tube and damage the small pump), place a tube over this, and cover with adhesive plastic film. This technique makes an elegant NPWT dressing for a single finger that is not bulky.

Figure 13  An example of how quickly a tissue defect can fill up with granulation tissue when using NPWT.   Note that NPWT will not stimulate the last phase of healing: epithelialization is the phase where skin cells migrate over the wound. Once the wound has granulated, as in the bottom picture, we can stop the NPWT and let it heal on its own or place a skin graft over this. We used the Polymem dressing here in combination with a PICO pump for 14 days. 

wa npwt finger.JPG

Figure 14  Another method to achieve an NPWT dressing on a finger. In this example, NPWT was used to cover a full-thickness graft on a thumb defect. A thin non-adherent barrier netting is placed on the graft, covered with regular cotton gauze. The suction tube is placed on this, and adhesive plastic film is paced over this in a sandwich technique. Note that the plastic film extends quite far up to the lower end of the forearm to ensure an airtight seal around the tubing. copyright: Niimi et al, 2018: https://www.researchgate.net/figure/Application-of-a-single-use-negative-pressure-wound-therapy-system-to-fix-full-thickness_fig2_327195111; creative commons license Attribution 4.0 International (CC BY 4.0)

wa uridome NPWT.jpeg

Figure 15  We are constantly looking for new methods to make a cheap and practical finger NPWT dressing. Recently have started experimenting with uridomes. These are actually made to deal with male incontinence and come in different sizes. The smaller sizes can be used to create an airtight dressing around a finger, and the suction tube to the pump can be connected to the end of the uridome. You will need a medium ( gauze or foam) on the wound- NPWT will not work if you simply place the uridome on the wound and apply suction! You will still need some adhesive plastic film to make it adequately airtight at the upper end of the finger. NB! The uridome has to fit comfortably and not be too tight!

Abdominal NPWT

With abdominal NPWT, we do not mean treating skin wounds on the abdomen with NPWT.   Instead, Abdominal NPWT refers to managing an open abdomen temporarily with negative pressure. In gastric surgery, there are certain situations where the abdomen cannot or should not be closed straight away. In severe trauma, there may be some contamination of the peritoneal cavity requiring a second or third surgery within a few days. Sometimes the abdominal pressure is so high that the abdominal wall cannot be closed ( abdominal compartment syndrome).

Abdominal NPWT is often called "AbdoVAC". Remember that the term VAC actually refers to KCI/3M NPWT products and, strictly speaking, should only be reserved for when we use their products. 

Applying an abdominal NPWT is not difficult, but you should not perform this unless you have seen this done before. The critical aspect is that the medium ( gauze or foam) by no means can come into contact with internal organs /intestines as this can cause tissue damage or bleeding. A plastic sheet is used as a barrier between the NPWT medium and these organs. 

Most producers have complete abdominal NPWT kits that contain all you need to do this procedure. There is an ongoing discussion on which pressure setting to use for the open abdomen. Most specialists advise using a far lower pressure than we use in wound care. Often - 40 mmHg is enough to achieve good results; some use even lower pressures. 

If you do not have access to a kit, you can easily make an abdominal NPWT dressing yourself. You will need a large plastic sheet that is used as a barrier between the internal organs and the medium. The sheet must be large enough to cover the entire anterior abdominal cavity wall ( at least 10 cm cranial and caudally from the abdominal incision. Do not cut any holes into the sheet. Exudate from the abdominal cavity will find its way around the edges of the sheets. Over this, you place a thick cotton sheet or other absorbable material. Make sure that the cotton sheet can not come into contact with any internal organs or intestines. Place the suction tube on top of the cotton sheet and apply a sizeable adhesive plastic sheet over all of this to make an airtight seal. 

NPWT should not be used longer than absolutely necessary. Extended management of an open abdomen with NPWT can retract the fascia/abdominal wall muscles and make the final closure difficult. Below are some videos from different producers showing how they recommend an abdomen NPWT to be applied. 

Video 10  Demonstration of the Smith & Nephew Renasys Abdominal Kit 

Video 10  Demonstration of the KCI ABThera Kit 

Video 11 A video by HMP Medical about Best Practices to optimize patient outcomes in situations with an open abdomen. This video is almost 55 minutes long.

Link 1 This article about VacPack is in Norwegian and was published by the Norwegian Medical Society.  You will not be able to understand the text, but the images may be useful.  We are currently working on an English version of this material.  

Using a silicone crown for enteric fistulas

Sometimes we have a situation where an enteric fistula or stoma is situated in an area of an open wound. Using some tricks, it is possible to use NPWT to treat the wound even though there is a fistula/stoma present. Remember: the NPWT medium ( gauze or foam) should never come in contact with the intestine! 

To protect the enteric fistula/stoma from the NPWT medium, you can use a special silicone crown to isolate the fistula from the rest of the NPWT dressing. The video below explains this closer. 

Video 12 To isolate an enteric fistula /stoma from the rest of an open wound during NPWT, we can use a silicone ring called a crown. If you do not have access to a silicone crown like this, you will have to improvise with something similar, preferably also made of silicone.