08. Negative pressure wound therapy (wound VACs)

What does wound "VAC" stand for?

Vacuum assisted closure (VAC)

What are the types of wound vac machines? (2)

VAC ultra (large vac): Often used in hospital setting

Activac: Small portable vac, used at home

What is the component of a wound vac that's placed inside the wound?

The sponge/foam

What is used to keep the sponge in place within a wound vac?

The "drape", a cling-wrap like material that seals the sponge in the wound

What is the trac pad in the wound vac?

The circular disc with tubing, connecting the sponge in the wound with the wound vac machine

How does a wound vac promote healing to the wound bed?

Delivers negative pressure/ sub atmospheric pressure (suction) to the wound bed

How is the sponge cut before being placed in a wound?

Cut to fit the shape of the wound

What is the process for changing the sponge in a wound vac?

Change the sponge every few days, repeatedly putting in a smaller sponge

Why is it important that a wound vac is a closed system?

Any air leaks will cause the system to fail

What is the first step for preparing a wound vac?

Cut the sponge to the shape of the wound

Why is it important that the sponge is NOT bigger than the wound itself?

Because it's too wet for healthy skin, must stay within confines of the wound

How large do we cut the drape in relation to the sponge?

3-5 cm larger than the sponge

Can we use multiple pieces of drape on a wound vac?

Yes

What is the saying to remember how to seal the VAC drape?

1-2-blue

How large should the hole in the drape be that's covering the sponge?

About the size of a quarter

What do we insert in the hole that's the size of a quarter on the drape?

Insert the TRAC pad over the hole

What are the benefits of a wound vac? (2)

Macrostrain and microstrain

Define macrostrain in a wound

When you can visually see the tissues within a wound vac getting pulled together

Does a wound vac help remove infectious materials from a wound?

Yes

Define microstrain in a wound

When you increase cell proliferation, increase metabolic activity, increase fibroblast migration and increase granulation tissue growth

What are MMPs?

Matrix metalloproteinases, an enzyme found within chronic wounds

How do MMPs contribute to healing wounds?

Excess MMPs prohibit complete oxygenation of hemoglobin

When should we use a wound vac? (3 times)

Traumatic wounds (acute or chronic)

Partial thickness burns, dehisced wounds, ulcers, skin grafts

Can maintain a healthy wound until wound is surgically closed

When it is contraindicated to use a wound vac? (4 instances)

Malignancy in wound

Untreated osteomyelitis

Eschar/slough in wound bed over 25% of wound area

Exposed vessels or organs

What is a big precaution against using a wound vac?

Active bleeding (stop with alginate 24h or xeroform gauze)

What are the settings that can be changed on a wound vac? (4)

Continuous suction vs dynamic pressure control (intermittent)

Suction pressure

Intensity (ramp up)

Frequency of dressing changes

When is continuous vs dynamic pressure used in a wound vac?

Continuous for first 48 hours, then switch to dynamic

When is it best to leave a patient on continuous suction? (3 times)

Difficulty maintaining an airtight seal

Tunnels or undermining areas

High levels of drainage past 48 hours

What is the most typical suction pressure?

125 mmHg

When is it recommended to turn up the suction on a wound? (4 times)

Excessive drainage

Large wound volume

Difficulty maintaining seal

Using versa foam (white foam)

When is it recommended to turn down the suction on a wound? (3 instances)

Pain unrelieved by medications

Some bleeding

Compromised circulation or PVD, causing increased pain

Define the intensity of a wound vac

The rate at which the target pressure is reached in a wound

When is it recommended to use a low intensity on a wound vac? High intensity?

Low: If wound is painful

High: If wound is difficult to seal

How frequently should wound vac dressings be changed?

Follow MD's instructions, but generally every 48-72 hours

What are the types of foam that can be used in a wound vac? (2)

Black foam

White foam

What is one way to reduce pain in a wound vac by changing the foam?

Change the black foam to a white foam

What is the main difference between white and black foam?

White foam is denser and thicker, black foam is thinner

How can you use a white foam for a thin, deep wound?

Pack it into a wound and create a tail

What should we wash the wound with before applying the wound vac?

Soak with normal saline (to loosen out the flesh that's grown into the sponge)

How large do we make the sponge for a wound?

Exactly the size of the wound or slightly smaller

Can the sponge on a wound vac touch healthy skin?

No, don't allow it to touch healthy skin

How long is the maximal time that you can turn the wound vac off for?

Max 2 hours over a 24 hour period

Should a skin graft come in contact with a wound bed?

Yes, the skin graft should touch the wound bed for it to "take"

What is the purpose of using a wound vac for a skin graft?

Reduces the amount of fluid in a wound, makes the skin more likely to "take"