Tips and tricks for NPWT

 

  • We believe this to be the most comprehensive list of tips and tricks for NPWT available on the internet. These tips come from over 20 years of experience using NPWT as a treatment modality. If you have any other tips and tricks, please send us an email. 

  • Never start with NPWT unless you have a logistics plan of when to change the dressings, who should change the dressings, and who should be contacted if something goes wrong during the treatment. If your patient is on a ward at your institution, the attending staff have to have some basic knowledge of NPWT and understand that a failure of the pump or leakages can lead to severe infection within a short time. If you are treating an outpatient, the patient needs to be informed extremely well about the potential dangers of NPWT, and the patient has to be able to get the NPWT dressing removed if anything goes wrong during the treatment at home. 

  • Never start with NPWT if you are unsure whether the wound fits this treatment. If the wound is smelly and contains slough, it will first need to be debrided and treated with antibacterial wound care products for some time before considering NPWT. If you doubt whether the wound is well enough prepared to start with NPWT, it is probably not. 

  • Take care to remove any remnants of cream/ lotion from the patient's skin before applying the adhesive plastic film. You may have to use a washcloth with lukewarm water and a gentle soap to prepare the skin properly. Pat the skin completely dry afterward. 

  • If you have access to liquid barrier products  ( the type you use to prevent moisture damage), it is good to apply this onto the skin before applying the adhesive film. The plastic film will adhere much better to the skin, and the barrier product can prevent moisture-associated skin irritation from sweat accumulating under the plastic film. Apply the barrier product liberally everywhere where you expect to place adhesive film. 

  • Aging skin is often dry and flaky. The adhesive plastic film usually does not adhere as well to this type of skin. A tip here is to apply a sheet of the plastic film first as the base layer. Cut a hole for the wound in this layer. Place the wound filler into the wound and cover this with a second sheet of adhesive plastic film. Plastic adheres very well to plastic! Even though the base layer may not adhere as well to the skin, this technique usually helps achieve a better seal.  

  • Getting an airtight seal is the essential part of your NPWT dressing. So do not rush this part of the procedure. Hasty and sloppy work at this stage will only give you headaches, and you may end up removing the dressing and having to start all over again. 

  • The transparent adhesive plastic film we use in NPWT actually allows for some evaporation of water. This is important because we want to avoid having much condensate collecting underneath the plastic film. We sometimes see colleagues reinforcing the plastic sheets with several additional sheets to ensure it is completely airtight. When we place an additional sheet of plastic over another, we have blocked the possibility of evaporation. Yes, we will have to reinforce some parts of our NPWT dressing but be critical about where you place these additional strips of plastic adhesive. Do not place several layers of plastic adhesive on top of each other out of habit.

  • Never apply the adhesive plastic film in a tight manner. Some caregivers think that they will achieve a better seal if they lay the plastic film while they pull on one side of it. On the contrary, pulling on the plastic film upon application will actually cause it to loosen from the skin earlier! In addition, you can harm the patient's skin by applying the plastic film too tightly - sometimes this can cause blistering of the skin and may cause the patient pain!

  • When applying an NPWT dressing around toes, fingers, inguinal area, rima internates, close to the axilla, or in other difficult anatomical regions, it is very useful to have stoma paste at hand to seal any air leakages.  

  • Packing several toes or fingers into an NPWT dressing can be difficult and frustrating. We advise you to use the sandwich technique for this described in the previous chapter. It is essential to pad the areas between all toes/fingers well to avoid these being squeezed together. It is also wise to start at a lower pressure, for example - 60-80 mmHg, to check that the patient tolerates this well. 

  • Do not press the wound filler ( gauze or foam) into the wound cavity. Using gauze, lay it " fluffily" into the cavity. When using foam, cut the foam slightly smaller than the diameter of the wound cavity. 

  • Never cut the foam or gauze while holding it over the wound area. Tiny particles from the cut material will fall into the wound! 

  • When using gauze, be aware that some cotton thread may be left behind when removing the gauze wound filler at dressing changes. Never place gauze wound filler into wound cavities where you cannot see the entire cavity with your eyes.  

  • Be very careful when you place black or green foam into cavities where you do not have direct visualization of the entire wound cavity. Sometimes black or green foam will adhere firmly to the wound bed in only a few days. The foam sometimes tears and rests can be left behind in a deeper wound cavity upon removal. We have witnessed several examples where patients had severe infections due to pieces of foam accidentally left behind in a deeper wound cavity. 

  • If you would like to use foam in a deeper wound cavity with poor visualization of the entire cavity, we advise you to use white foam. This is made of much stronger material and will not tear as easily. Also, it does not adhere as firmly to the wound bed, making retrieval of the foam easier.  

  • Sometimes when the wound is more superficial, some caregivers think they have to thin out the foam. This is wrong.   Most producers recommend keeping the foam in the original thickness no matter how shallow the wound is. They explain that a thin foam will collapse a lot when negative pressure is applied, and this can lead to the foam not transporting fluid effectively from the wound bed. 

  • Whenever possible, try to avoid placing many small bits of foam into a wound cavity, especially if visualization of the cavity is poor. This is to prevent leaving a piece behind during dressing changes. If you have to use several foam pieces, write the number of pieces you used on the plastic film and record this in the patient's journal.

  • Remember that you can combine gauze and foam as wound fillers in the same wound. If you, for example, are treating a deep wound with a very irregular wound bed, it can be useful to cover the wound's surface with gauze first and fill the rest of the wound cavity with foam. 

  • Remember that all areas of the wound that are not in direct contact with the wound filler, will not be drained for exudate! This is a concept we have called pooling. Exudate that is not drained out can quickly turn into pus in the anaerobic environment of an NPWT dressing. If larger cavities are not filled with wound filler, this can cause a severe infection.  

  • Whenever there are narrow channels or sinuses/tracts where foam or gauze will not fit, you will need to use a drain to prevent exudate pooling. This drain will work like a straw and is easy to change at dressing shifts. Note that a drain by itself does not promote the formation of granulation tissue like foam or gauze does, but it will prevent exudate pooling. Smith & Nephew has several drains available for this purpose. If you do not have access to these, you can make a drain from e thin urine catheter. You will have to cut multiple perforations along the length of the drain for optimal effect. Remember - you should never treat a fistula if it leads to internal organs or if you have no clue where the fistula's origin is. ​

  • If you have a situation with large areas of exposed tendon, it is usually very difficult to achieve coverage of this with NPWT.  If the tendon ist still covered with the tendon sheath you may be able to promote granulation tissue with negative pressure. However, if you see the tendon fibres exposed, then this is much more difficult. Smaller areas of exposed tendon ( ( about 1 x 2 cm)  may granulate over using NPWT if there is some granulation tissue already lying in close vicinity of the exposed tendon.  If the tendon is in an anatomical region where the tendon is moving a lot, you will definitely fail with NPWT alone.  Your only chance is to immobilize the tendon simultaneously, using a cast or an orthotic parallel to the NPWT.  Remember, never use wound filler directly on exposed tendon fibres- this will usually dry them out causing necrosis of the tendon.  You should always have a barrier netting ( for example silicone netting) as a barrier between the tendon and the wound filler. 

  • Modern NPWT pumps can be set to start the suction slowly so that the patient hardly feels any discomfort when the pump is turned on.  Most manufacturers call this the intensity setting of the pump.  If you have an older model of pump where you cannot determine the intensity at the onset of the suction, you can start at a lower pressure. You can for example, start the pump at -40 mmHg and the gradually increasing to say -80 mmHg in the course of a minute. 

  • We rarely see that a patient has much discomfort when using NPWT.  If the patient has a very painful wound it may, however, be wise to start the treatment at low pressure levels.  You could for example set the pump to -60 mmHg the first days and then increase to -80 mmHg the following days so that the patient gets used to the treatment. 

  • Many producers recommend changing the dressings every third day.  We sometimes extend the NPWT dressing changes to up to 7 days, but only when we are treating a very clean wound.  From our own extensive experience with NPWT we see that wounds granulate quicker when we change the dressings more frequently.  We do not have any good explanation for this.  Could it be that we keep the bacterial numbers lower when we change the dressing more frequently?  Our own theory is that the foam or gauze, when compressed for several days looses its stimulating effect on granulation tissue. So whenever possible change the NPWT dressings twice a week. 

  • When using NPWT  continuously for a few weeks, it is common to see a stagnation in the speed of granulation formation.  At this stage there are several things you can do.  It may be a good idea to take a few days break from NPWT - this can be good for the skin which may get irritated by weeks of coverage with a plastic film.  Upon re-starting the NPWT a few days later may also stimulate the granulation tissue formation better.  Another thing you can try is to increase the pressure setting - if you have been treating the wound at,s ay, -80 mmHg then you may want to increase the pressure to -125mmHg for the following weeks, if your pump is capable of this.  Some pumps have a so called intermittent mode. This means that the pressure cycles go up and down during the treatment.  Intermittent mode is also something you can try to stimulate the granulation tissue , if your pump has this mode available.

  • NPWT with simultaneous irrigation and dwell time ( NPWTid),  is the ultimate NPWT treatment.  In our hands it gives the most reliable results and we can be less anxious about the risks of infection.  The commercial products available for NPWTid are very expensive and not available for most healthcare settings in Africa.  With some workaround methods you can make a DIY NPWTid solution very cheaply. Please refer to our chapter on NPWT in area with limited resources.  

 

  • If the patient has a lot of pain at dressing changes you can try to fill the foam or gauze with body temperated NaCl solution and let it dwell for about 10 minutes.  Be aware that black and green foam is not much affected by applying NaCl - it may help a bit, but not always sufficiently. In these cases we sometimes need to saturate the foam with lidocaine.  You may need quite a lot of lidocaine to saturate a larger piece of foam- but usually 20-40ml is sufficient.  let the lidocain dwell in the foam for about 15 minutes and this will usually make the removal of the foam more painfree.  

  • If we already know beforehand that the dressing change will be painful ( we have changed an NPWT dressing on the patient before) it may be wise to saturate the foam with lidocaine before we even remove the plastic film. Sometimes we simply cut the tubing leading to the dressing and inject lidocaine into the tubing leading to the wound filler. Cut the tube close to the dressing to avoid using unnecessarily much lidocaine and clamp the tube while the lidocaine is left to work for about 15-30 minutes.  

  • It is normal for the NPWT dressing to be slightly smelly at dressing changes.  If you have gained some experience and have changed many NPWT dressuings you will have a sense of what is the normal NPWT dressing smell and what smell should alarm you.  If the wound smells odd to you, it may be advisable to take a break from NPWT and to treat the wound with an antibacterial dressing ( for example iodine gauze) for a few days before restarting the NPWT treatment. 

  • At our clinic we routinely use super-oxidized water or a vinegar-bases wound rinse solution to rinse the wound and let it dwell fro about 10 minutes between NPWT dressing changes.  We have no scientific documentation for this practice.  We believe, however, that it helps to keep bacterial numbers at bay and may extend the dressing change intervals. 

  • Remember that NPWT does not help with the epithelialization process. In other words- once granulation tissue has filled the wound cavity, there is not much use in continuing the NPWT. The only exception is when we use NPWT over a split-thickness skin graft. 

  • Many caregivers never bother to read the pump's instruction manual and use it in default mode. If you have a more advanced pump, we absolutely recommend you read the instruction manual and learn how to change into different treatment modes, such as intermittent suction mode, which we discussed earlier in this chapter. 

  • Remember that all the air ( and all the smell) sucked from the wound is passed through the inside of the pump. Most pumps have active charcoal filters to neutralize the odor. After a few months, these filters are saturated and need replacement. A few years ago, we had pumps where we were unaware of this and reacted to a strange smell from the pumps. Today, all of our pumps are serviced regularly, and the filters are changed about every third month. If you use single-use pumps, you will not need to worry about service. 

  • If several caregivers at your institution have started using NPWT, you will sometimes encounter a strangely applied NPWT dressing. It is important not to make negative comments about this before the patient. Avoid remarks like " the one who made this NPWT dressing must have been a beginner." This sort of remark will help no one, least of all the patient, who will only become insecure.  Instead, try to get hold of the person who made that dressing and slik at forskjellige behandlere skifter vakuum bandasjen er det viktig at man ikke gjør negative kommentarer foran pasienten om den andres behandling. Uttalelser som "den som har lagt denne vakuum bandasjen må være en nybegynner" er til ingen nytte og vil bare gjøre pasienten usikker!

  • Patient compliance is essential when using NPWT. If you have an outpatient NPWT treatment, your patient may decide that they will remove the pump to do some chores in the field. This phenomenon is jokingly called a "VACation." The patient needs to be well informed that it is of utmost importance that the pump is connected at all times. 

  • If you are using a pump with a canister to collect exudate, it is normal for the canister's contents to look " yucky" after a few days. It is essential to inform the patient/ relatives about this.

Tips to get an excellent airtight seal

The better seal you have ( i.e., the less leakage) the better the results! This is usually easy to achieve on a leg or a thigh where there are large flat surfaces to attach the adhesive plastic sheets to. In other areas of the body like the perinuem, close to the anus, in skin folds, under the armpits, around fingers/toes or cløose to the hairline in the back of the neck this can be notoriously difficult. Remove all hair from the areas where the plastic film will be applied. remove any remnants of creams/lotions. You may need to use 75% alcohol to remove oily creams. If available, apply liquid barrier products liberally everywhere where you will apply adhesive plastic film - this will make the plastic film adhere better. 

If there are skin folds it may be necessary to cover these with a sealant product. You may use hydrocolloid plates, stoma paste, adhesive silicon plates or silicone paste for this purpose. Most producers of NPWT products also sell some sort of sealant material. 

Stoma plates which are self-adhesive hydrocolloid plates and you can cut these into appropriate sizes if they are available to you. One producer of stoma products is Eakin, and they sell hydrocolloid products in all shapes and sizes. On their website they have a lot of useful tips in how to use these products to achieve a good seal. 

Figure 1 An example of how adhesive hydrocolloid plates from Eakin are placed around a large sacral ulcer to achieve a good NPWT seal. If you click on the image above, you get to their website, where you can get many more useful tips on how to seal difficult anatomical areas. copyright all images: Eakin

Table 1 A small selection of some of the products we use to achieve an airtight seal in NPWT dressings.