Friday, December 5, 2008

A Doubting Florence Presents: Cool Stuff Nurses Do--Negative Pressure Wound Therapy

The most popular advice given to novice writers is "write what you know and where you come from." I come from a home care nursing background. The patients I work with are stable enough in their conditions to have most of their health monitoring done at home. The purpose of home care is to keep patients stable and avoid re-hospitalization. Wound care is a huge part of home care. The nurses are primarily responsible for teaching the patients and their caregivers how the wound originated, what can be done, as well as signs and symptoms of wound infection to monitor for on a daily basis. There are many many many types of wound care out there, each one has it's advantages and disadvantages. This post I will discuss one of my favorite types of wound healing- Negative Pressure Wound Therapy (NPWT for short).

WHAAA? NPWT technique involves putting a open ended foam inside the wound cavity, covering it with an adhesive drape, thus creating an airtight seal and a closed wound, and attaching a noncollapsible evacuation tube that is attached to a vacuum which applies a controlled subatmospheric pressure (usually between 125mmHg and 175mmHg below ambient pressure). The vacuum is also attached to a canister that collects the drainage as well as any bad wound spooge (not a clinical term) that the vacuum draws out of the wound. It is also known as vacuum-assisted closure, or wound vac-ing. I will refer to it here as "the wound vac." Studies of the wound vac appear to start to be published around 1997. Dr, Louis Argenta and Dr. Michael Morykwas found that vac therapy in animals increased blood flow to the wound, removed bacteria, and increased the rate of the good granulation tissue (a "good lookin" wound has a wound bed that looks like raw hamburger meat). The FDA started to approve wound vac therapy around 2000. It can be used both as inpatient and outpatient therapy. The goals of wound vac therapy, as defined by Argenta and Morykwas, are to increase patient comfort, decrease patient morbidity, decrease the cost, and decrease the length of hosptialization. There is a second type of NWPT out there, developed by Dr. Mark E. Chariker and Dr. Katherine F. Jeter in 1989. This involved using a Jackson Pratt drain (it's a plastic flexy drain that is inserted surgically. If you've ever seen one, it looks like a clear hand grenade attached to a tube) connected to wall suction in a patients hospital room. It's known as the Chariker-Jeter technique. Unfortunately, I wasn't able to find much on this technique- it started being commerically marketed in 2001. We don't use it at my agency. NWPT is usually discontinued when the foam dressing can no longer fit inside the wound because it is too shallow. Average length of therapy is about 9 to 12 weeks for larger wounds.

OKAY MS. SKEPTIC, WHERE IS THE SCIENCE? Glad you asked!!! There have been at least 300 peer-reviewed studies regarding the effectiveness of NWPT. For this blogpost, I was able to find and review about 7 studies in various journals, including one of the studies done in 1997 by the "wound-vac dads," Argenta and Morykwas (however there are lots more available). I also reviewed a study by Bendwald, that examined the use of NPWT following surgery for complex pilonidal disease (a common type of cyst on the anorectal area). A paper by Jerome outlines the recent advances in NPWT. Bharestani performed a retro exam of clinical outcomes in neonatal and pediatric wounds. One extremely interesting study to read was one done by Leininger, about NPWT and soft tissue injuries in Iraq. Very surprisingly, their group of patients had a wound infection rate of 0 as well as no wound complications. The wound vacs were applied and reapplied in a completely sterile field by one of the surgeons at the 332nd Air Force Theatre Hospital in Balad, Iraq.

PROS Out of 300 wounds of all types (chronic, acute, subacute and nonhealing), Argenta and Morykwas found that 296 of the wound responded favorably to the vac. Jerome adds that NPWT to reduce excess moisture in the wound which reduces burden to the wound bed and surrounding skin, and also prevents growth of toxic stuff. Bharestani's study found that NPWT- combined with antibiotic therapy, surgical debrediment, optimum medical care and optimum nutrition- revealed a 92 percent successful wound closure rate. The foam is designed to have a pore size of about 400 to 600-um which maximizes cell growth. Wound healing tends to be faster with the wound vac. Also, one could take a wound that would require daily dressing changes and decrease visits to three times weekly. That is good in keeping Medicare and insurance claims down. When used properly, it can cut down on wound infection. It also has a very very low mortality rate. The vac appears to be useful for acute, chronic and non-healing wounds. The foam dressing is trimmed at the bedside for the specific size and shape of each wound. It does not have to be a completely sterile process so it can be done in the home (but you want it as clean as possible). Some pain was noted by patients, but most pain appeared to subside after the wound vac had been on for about 30 seconds. The vac is portable and allows for increased mobility for patients. One of the test subjects in the Bendwald study was able to attend high school using a portable wound vac.

CONS Most of the studies I reviewed stated that in order to truly call NWPT effective, more long-term well-designed studies are needed. Weaknesses of the current research include small samples of the same types of patients, lack of hard-core experimental design and lack of sensitive outcome measures, and lack of documentation of pain, length of stay, and cost of treatment. For wounds covered with dead tissue, surgical removal of the dead stuff is required before instituting the wound vac, or else it will be ineffective. Special training is needed, so not all nurses can put on wound vacs. Some patients don't like carrying around a bulky vacuum attached to them by a flimsy tube. And at times the wound vac can be noisy and distracting for some. (I would describe the sound it makes as sort of like a cross between a bull snort and a coffee perculator) Like any treatment, it has the potential to be put on improperly and if so, the vacuum pressure can cause damage to the healthy skin around the wound. Also there is a potential for wound infection if nurses don't practice good clean technique and proper universal precautions (handwashing, gloves, etc.) while performing wound care. And it requires A LOT of adhesive dressing, so if you are sensitive to medical tapes and bandages, you might want to carefully monitor how your skin reacts. There is at least one mention in at least one of the studies I reviewed that stated that a test subject had to discontinue wound vac treatments due to skin sensitivity and the adhesive. The wound vac IS NOT RECOMMENDED for wounds that are the results of tumors or cancers, as they can actually help enhance the tumor growth.

HOW ARE NURSES INVOLVED? Nurses in home care undergo a series of training and re-training classes involving wound vac administration, set up and rountine care. This is usually supplied by a clinician at the company that supplies the wound vac supplies. The nurses monitor the wound multple days on a weekly basis. My agency usually changes the wound vac dressing every Monday Wednesday and Friday, but no less than three times weekly. We are responsible for keeping accurate weekly measurements of the wound's length, width and depth, as well as describing any drainage amount, color and consistency and teaching the families how to care for the vac machine and helping the patient and the caregivers troubleshoot any problems with the machines, mechanisms and therapy. Most physicians who are working with us look to the nursing staff to advise THEM on the protocol and parameters of wound vac use. Plus, many of the research studies on wound vacs are performed by Wound Ostomy Continence Nurses (WOCNs), who are nurses who are educated and certified to specialize in wound care.

SO, IS IT REALLY COOL? I think it is. The vac does a really good job at keeping wounds clean and dry and necrotic tissue (the dead stuff) rarely returns when a patient is on the vac. It's neat to watch a stubborn wound respond to the vac. Our agency has a good working relationship with the manufacturer of the wound vac. It's pretty easy to obtain one for a patient if a doctor orders it, and the clinician that works with us is very available if we have questions. Many patients like it because it really is minimally invasive and cuts down on nursing visits and daily dressing changes...and money, which is why insurance companies like it too. If you are reading this and think that you or someone you know might be a candidate for a wound vac, please first visit the doctor you are working with and discuss it with him/her.

WHAT'S NEXT FOR JENN AND NPWT??? Are you implying something?? ;) Actually, I have been toying with the idea of becoming a WOCN. I really like to do wound care. It's a great type of nursing for a skeptic, as one has to apply their critical thinking skills as well as practice the scientific nursing method of assessment, diagnosis, intervention, results and eval on a regular basis. I could do what I do now, but it would be more focused towards a specific type of patient and...they would pay me more money. So I am definately interested in being a WOCN. But, there are some days I also wanna be a Care Bear. So we'll see.

References for this blogpost
Leininger, B.E., Rasmussen, T.E, Smith, D.L. Jenkins, D.H., Coppola, C. Experience With Wound VAC and Delayed Primary Closure OF Contaminated Soft Tissue Injuries in Iraq. Journal of Trauma Injury, Infection, and Critical Care, 2006;61(5):1207-1211.

Bendwald, F.P, Cima, R.R., Metcalf, D.R., Hassan, I. Using Negative Pressure Wound Therapy Following Surgery for Complex Pilonidal Disease: A Case Series. Ostomy Wound Management, 2007;53(5):40-46.

Verrillo, S.C. Negative Pressure Therapy for Infected Sternal Wounds: A Literature Review. J WOCN, March/April 2004:72-74.

Baharestani, M.M. Use of Negative Pressure Wound Therapy in the Treatment of Neonatal and Pediatric Wounds: A Retrospective Examination of Clinical Outcomes. Ostomy Wound Management 2007;53(6):75-85.

Jerome, D. Advances in Negative Pressure Wound Therapy. J WOCN, March/April 2007:191-194.

Negative Pressure Wound Therapy

Argenta, L.C. and Morykwas, M.J. Vacuum-Assisted Closure: A New Method for Wound Control and Treatment: Clinical Experience. Annals of Plastic Surgery, 1997;38(6):563-576.


E said...


I’m a physician and inventor in FL. I happen to stumble across your blog on NPWT and am impressed by your excellent writing style and methodical research.

The reason for my writing is that I have invented a new wound care system that is superior to NPWT. I am interested in bouncing some ideas off you. You can read my profile at

and reach me via elin at ingenious dot com


Ed Lin

Patrick said...

Nice write up Jenn!

I'm sure you'll contact Ed and put his superior system to the test!

Jenn said...

Hi Patrick!
Actually, I did some digging. Impressive professional resume and seems like a kindhearted, well-meaning fellow. However, I'm still a wee bit skeptical. For now, if I had to choose, I'd stick with the NPWT. Especially since the O ACE SYS (Dr Lin's system), according to the website, is pending licensure and there are no studies found of the O ACE SYS in the search engine google (the only two references are from Dr. Lin's website, and it consists of approximately 3 paragraphs). I'll keep my eyes peeled in the future to see how Dr. Lin's system does in clinical trials. :D

Shay2you said...

I found your blog after googling woundvac...great article. My best friend has a woundvac right now. She had emergency surgeries...yep, surgeries about 5 weeks ago to remove a T4 tumor attached to her oerter...had to remove a kidney, ovary, the oerter and the big ole tumor. We have been home for about 10 days and have the greatest in-home health care nurse who comes 3 times a week to change the dressing. I've done my best to help her with this and it absolutely amazes me how this thing works!!!! The wound has decreased by half just this week. Yippee!!!

Shay in Denver