'Indirect VAC': a novel technique of applying vacuum-assisted closure dressing.
Abstract: Vacuum-assisted closure (VAC) wound dressing is increasingly used to assist closure in various wounds ranging from simple finger pulp defect to complex wounds such as laparostomy or infected sternotomy. The traditional application of direct vacuum therapy can cause discomfort and put the patient at risk of injuring the affected area while mobilising. We describe a novel technique of applying VAC therapy indirectly which is much more comfortable and convenient for the patient while mobilising.

KEYWORDS Dressing / Vacuum / Wound
Authors: Durai, Rajaraman
Hoque, Happy
Davies, Tony W.
Pub Date: 10/01/2008
Publication: Name: Journal of Perioperative Practice Publisher: Association for Perioperative Practice Audience: Academic Format: Magazine/Journal Subject: Health; Health care industry Copyright: COPYRIGHT 2008 Association for Perioperative Practice ISSN: 1750-4589
Issue: Date: Oct, 2008 Source Volume: 18 Source Issue: 10
Accession Number: 200343267
Full Text: Introduction

VAC wound dressings are increasingly used (Jerome 2007) in the management of various wounds ranging from finger pulp defects (Attar et al 2007) to laparotomy (Bettschart et al 2002, Penn & Rayment 2004) and sternotomy with deep wound infection (Ibrahim & Refaat 2007). VAC therapy improves blood flow, reduces local tissue oedema and removes excess fluid and bacteria from the wound (Venturi et al 2005). It also alters the cytoskeleton of the cells causing increased cellular mitosis (Venturi et al 2005). It is common for the device to be applied straight on to the sponge covering the wound (Direct VAC). When the VAC dressing is applied particularly to a sacral bed sore or diabetic foot, the Therapeutic Regulated Accurate Care (TRAC[R]) pad tubes protrude from the surface and can cause discomfort to the patient. The patient could be injured at the wound site while mobilising.

Here, the authors describe a convenient method of applying VAC, which we call 'Indirect VAC application technique', which we have found to be more comfortable for the patient. It also avoids the VAC TRAC[R] pad tubing protruding from the surface and will be useful for routine use in all types of wounds requiring VAC dressing.

Indirect VAC therapy

The VAC dressing kit comprises of a sponge (Figure 1), two big airproof adhesive films, a canister, TRAC[R] pad tubes for connecting the sponge and the canister and a machine for producing a vacuum. A long thin strip of sponge is required for indirect VAC therapy (or tail VAC). Such a strip can be cut from the main sponge (Figure 1d). Then the remaining main sponge is cut to the correct size to match the contour of the wound. The big sheet of adhesive polyfilm that comes with the kit may be cut into several small strips (Figure 1B). It enables the physician to apply the VAC dressing comfortably in difficult areas without any leaks.


The main sponge is applied to the wound and covered with polyfilm strips (Figure 2A). Near the main sponge covering the wound, a strip of polyfilm is applied on to the bare normal skin away from bony prominences and areas subject to pressure. A small aperture is made in the polyfilm covering the wound and the thin strip of sponge that was excised at the beginning is applied on to the aperture and spread out on to the polyfilm on the bare skin (Figure 2B). The strip of sponge is covered with polyfilm strips (Figure 2B). Another aperture is made on to the polyfilm covering the sponge strip and the VAC TRAC[R] pad (Figure 1A) is applied. Figure 2C shows the functioning indirect VAC dressing in place.




Vacuum dressings help in rapid wound healing. The reticulated cells of the sponge evenly distribute the negative pressure. The VAC dressing is changed every three days, reducing nursing time, and the canister is changed once a week or when full. The VAC dressing also shrinks the size of the wound reducing the need for skin grafting. If a skin graft is required, VAC prepares the bed of the wound so that the uptake will be optimised (Espensen et al 2002). In diabetic foot sepsis, VAC may be applied after toe amputation or wound debridement to allow the patient home using the VAC dressing (Figure 3) and therefore reducing hospital stay. The diabetic foot wound is usually not suitable for immediate skin grafting but the VAC is of immense help in preparing the field for future grafting (Valenta 1994). Although the vacuum is used extensively in various situations (Lemaire et al 2008, Petzina et al 2008, Zwillinger et al 2008) and allows the patient to go home early (Wu & Armstrong 2008), recent systematic reviews did not find enough evidence to support its use in wound healing (Gregor et al 2008, Ubbink et al 2008). VAC removes tissue fluid, thereby decreasing local oedema and shrinks the wound. It also facilitates increased formation of new blood vessels and granulation tissue which is optimal at 125 mmHg (Thomas 2001). Experiments show that intermittent vacuum therapy may work better than continuous negative pressure settings (Philbeck 1999). At the cellular level VAC, using the sponge, caused increased cellular growth, chemotaxis and proliferation without increasing the apoptosis (death) of the cells (McNulty et al 2007). VAC therapy may or may not affect the bacterial load in the tissues (Muller 1997, Ubbink et al 2008). For efficient therapy, any eschar and slough should be debrided prior to application of VAC because they can block the pores of the sponge.

Wound healing occurs by three methods:

* primary intention

* secondary intention

* tertiary intention.

Healing by primary intention occurs when the wound is closed primarily, for example, after excision of a cutaneous lump and closure of the wound. When a wound is left open to heal by nature, the mechanism is called healing by secondary intention. Granulation tissue and fibroblast fills the gap and the fibroblasts shrink the wound. This happens in abscesses after incision and drainage. VAC increases the granulation tissue formation and also reduces the size of the wound by negative pressure and removal of tissue oedema.

Here the wound heals faster than simple secondary wound healing alone, i.e. open wounds without VAC. When a wound is left open for a few days and subsequently sutured, the process of healing is called healing by tertiary intention or delayed primary closure.

We have found indirect VAC technique very useful in healing pressure ulcers. Over the past six years, we have used this method of VAC dressing in at least 200 patients. The types of wounds in which Indirect VAC was used varied from diabetic foot to necrotising fasciitis wounds after debridement. We have found this technique to be much more comfortable to the patients. Within the time period of observation, no incidents of trauma from VAC were observed from this indirect technique.

Two similar techniques have been described which also decrease patient discomfort. The 'bridging technique' (Banwell et al 2002, Venturi et al 2005) and 'heel dressing' (Schneider et al 1998) are similar to our VAC dressing and usually applied to the foot alone. The polyfilm is used as a single piece whereas we describe the adhesive polyfilm being cut into small pieces and applied as required. Additional pieces of sponges can be added to the second (indirect) sponge to extend the application site of the TRAC[R] pad to a convenient and comfortable place. This is useful in sacral pressure ulcers. In a custom made VAC GranuFoam[R] Heel Dressing (KCI, Kidlington, UK), the extension sponge (Heel) comes with the kit itself. The dressing TRAC[R] pad is placed on top of the foot. In the Heel dressing, VAC is often applied to the heel over a skin graft and the patient can be allowed to mobilise early without losing the skin graft. In our technique, we cut the heel shape from the main sponge ourselves and therefore reduced the cost of the dressing without the need for a special heel dressing.

Close proximity to large vessels is a contraindication to VAC therapy. Other contraindications include the risk of haemorrhage, extensive necrotic tissue, osteomyelitis, malignant wounds and an underlying entero-cutaneous fistula.

Direct application of the VAC TRAC[R] pad may cause significant discomfort and there is a potential risk of causing injury. The authors believe that the new technique (Indirect VAC) will improve patient comfort and may avoid potential injuries.

Provenance and Peer review: Unsolicited submission; Peer reviewed.


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Bettschart V, Vallet C, Majno P et al 2002 Laparostomy with vacuum dressing after liver transplantation Transplantation Proceedings 34 (3) 777-778

Espensen EH, Nixon BP, Lavery LA, Armstrong DG 2002 Use of subatmospheric (VAC) therapy to improve bioengineered tissue grafting in diabetic foot wounds Journal of the American Podiatric Medical Association 92 (7) 395-397

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Rajaraman Durai


Specialist Registrar, Department of Surgery, Queen Mary's Hospital, Sidcup

Happy Hoque


Consultant Surgeon, Department of Surgery, Queen Mary's Hospital, Sidcup

Tony W Davies


Consultant Surgeon, Department of Surgery, Queen Mary's Hospital, Sidcup, UK

Correspondence address: Department of Surgery, Queen Mary's Hospital, Sidcup, DA14 6LT. Email: dr_durai@yahoo.com
Table 1 Case study: Application Vac dressing when a major vessel is

In our reported case (see Figure 2), the patient, an intravenous
drug abuser, underwent debridement of necrotic tissue in the left
groin. The femoral artery was exposed and there was only thin
fascia covering the artery. A Mepitel (Direct Medical, Texas, USA)
dressing was used to protect the blood vessel before the VAC was
applied (KCI, UK) using a portable vacuum machine. Using the
indirect VAC technique and removing the TRAC[R] pad from the groin
crease, allowed the wound to granulate while the patient mobilised.
Within two weeks, sufficient granulation tissue had formed to
protect the vessels and allow standard dressings while the wound
healed by secondary intention.

Table 2 Tips for successful and comfortable application of VAC

Suggestion                           Reason

Turn off the machine and             Suction will cause pain
disconnect the VAC tubing before
changing the dressing

Make sure the dressings              Otherwise the therapy will not
are air tight                        work

Any slough (dead tissue) and         Will obstruct the VAC sponge
eschar should be excised

Make sure VAC sponge does not        Vacuum on normal skin is painful
contact the normal skin

When the wound affects pressure      Otherwise the patient may get
points such as sacrum, heel etc,     further pressure sores from the
use the method described by us to    VAC tube
move the TRAC pad well away from
the wound

If you suspect an enterocutaneous    VAC is contra-indicated
fistula or a big blood vessel
underneath the VAC dressing inform
relevant surgical team

Change the canister earlier than     VAC will not work when canister is
seven days when it is full           full
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