Re: Interpretation of the NHSN surgical site infection definition for sternotomy infections

25/09/2013 at 11:49 am #70504 Quote

Wilkinson, Irene (Health)

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Wilkinson, Irene (Health)

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Hi Glenys,

Personally I believe the NHSN definitions are overly complex. I can understand the reason for distinguishing superficial infections from deep/organ space, but really what is the purpose of distinguishing deep from “organ space”? The likely causes/sources of infection and hence preventive measures would be similar.

Regards,
Irene

Irene Wilkinson
Manager, Infection Control Service
SA Health
Irene.wilkinson@health.sa.gov.au

Hi John,

While there is no muscle there is fascia and if involved you would proceed with using the deep definition to see if you meet the other criteria. From your description it seems in your cases you would meet b plus 1 signs of infection confirming it was a deep infection.

The definition seems fairly straight forward to me and I have found it very easy to use over the years. It is a definition for surveillance purposes not clinical management.

By definition an organ space infection does not include the wound, hence “infection deep to the deep fascia a deep (or organ space infection)” is not the correct application of the organ space definition.

Vac dressings can be used on lots of wounds including superficial sternal wounds (see below). The foam is cut and contoured to fit the size of the tissue defect, and covered with an adhesive drape and connected through the evacuation tube to the vacuum pump. There is no exposure of the wound bed/surface using these devices.

From memory there is usually an percutaneous suture in closure of a sternal wound.
Bapat V et al. Experience with Vacuum-assisted closure of sternal wound infections following cardiac surgery and evaluation of chronic complications associated with its use. J Card Surg. 2008 May-Jun;23(3):227-33Department of Cardiothoracic Surgery, St Thomas’ Hospital, London, UK. vnbapat@yahoo.com
Dezfuli B et al, Treatment of Sternal Wound Infection With Vacuum-assisted Closure. Wounds. 2013;25(2)

Regards

Glenys

Glenys Harrington
Consultant
Infection Control Consultancy (ICC)

PO Box 5202
Middle Park
Victoria, 3206
Australia
H: +61 3 96902216
M: +61 404 816 434
infexion@ozemail.com.au
ABN 47533508426

Thanks Glenys

However, there is no muscle overlaying the sternum and the deep fascia is just above the periosteum of the sternum.
For the most part there is just skin and subcut tissue in front of the sternum. These tissues overlying the sternum are very thin in most people.
And so it is nonsensical to distinguish superficial from deep based on this definition in my view

I don’t think that most surgeons put a closure layer beneath the skin once the sternum is wired- it is impossible. Effectively, then, opening or dehiscence of the incision will expose the fascia. Similarly, I cannot see that application of a vac can be done to a ‘superficial’ wound as the fascia will be exposed in these sort of wounds.
I could cope if the definition specified in this case that infection deep to the deep fascia a deep (or organ space infection); however that is not what it says.

We are long overdue for a better NHSN SSI definition…., esp for sternal wounds

John

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Dr John Ferguson
Director, Infection Prevention & Control, Hunter New England Health
Tel 61 2 4921 4444 | Fax 61 2 4921 4440 | Mob +61 428 885 573 | john.ferguson@hnehealth.nsw.gov.au | http://www.hicsiganz.org

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Hi John,

Whether or not these wounds are superficial or deep depends on the first part of the definition as to what tissue is involved. This question has to be answered before progressing to the rest of the definition.

Superficial – Infection occurs within 30 days after any NHSN operative procedure and involves only skin and subcutaneous tissue of the incision

Deep – Infection occurs within 30 or 90 days after the NHSN operative procedure and involves deep soft tissues of the incision (e.g., fascial and muscle layers)

If only skin and subcutaneous tissue are involved it meets the superficial definition as from your description c below is met and, I’m assuming that the patient had at least 1 of the sign or symptom below.

patient has at least 1 of the following:

a. purulent drainage from the superficial incision

b. organsims isolated from an aseptically-obtained culture of fluid or tissue from the superficial incision

c. superficial incision that is deliberately opened by a surgeon and is culture-positive or not cultured

and

patient has at least one of the following signs or symptoms of infection: pain or tenderness; localized swelling; redness; or heat. A culture negative finding does not meet this criterion

d. diagnosis of superficial incisional SSI by the surgeon or attending physician

If deep soft tissues (e.g., fascial and muscle layers) are involved it will meet the deep definition as from your description b below has been met and I’m assuming that the patient has at least 1 of the sign or symptom below.

patient has at least one of the following:

a. purulent drainage from the deep incision

b. a deep incision that spontaneously dehisces or is deliberately opened by a surgeon and is culture- positive or not cultured

and

patient has at least one of the following signs or symptoms: fever (>38C); localized pain or tenderness. A culture-negative finding does not meet this criterion.

c. an abscess or other evidence of infection involving the deep incision is found on direct examination, during invasive procedure, or by histopathologic examination or imaging test.

d. diagnosis of a deep incisional SSI by a surgeon or attending physician.

Hence in the first instance you need to know what level the surgeon has opened these wounds too as VACs can be used on superficial or deep would infections.

Just on organ space infections – these wounds as described would not be considered an organ space infection as such infections exclude the skin incision, fascia, or muscle layers, that is opened or manipulated during the operative procedure (i.e. the incisional wound is not involved at all). In this surgical setting an organ space infection would be something like osteomyelitis of the sternum without surgical incision/wound involvement.

I use a definition checklist (i.e. it either meets or does not meet the criteria) when training staff in the interpretation of the definitions for surveillance purposes.

Can send a copy if you like.

Regards

Glenys

Glenys Harrington
Consultant
Infection Control Consultancy (ICC)

PO Box 5202
Middle Park
Victoria, 3206
Australia
H: +61 3 96902216
M: +61 404 816 434
infexion@ozemail.com.au
ABN 47533508426

Dear All

Would appreciate advice on interpretation of the definition (below)

In two sternotomy cases, there has been prolonged ooze post op (several days) and the surgeon concerned has opened the wound on the ward and then instituted vac dressings
The cases required prolonged nursing management but did not come to formal debridement or removal of sternal wires etc. CT scans did not show retrosternal collections (ie not organ space infection)

In my view, this constitutes a ‘deep’ wound infection. What would others say?
Our other surgeons would have usually taken such cases to theatre and performed open debridement

in one case the culture grew Serratia
in the other, culture was no growth; in that case, the determination rests then on whether we had ‘purulent drainage’ observed from the ‘deep incision’
it does beg the question as to how one gauges from what level the drainage is coming fron and also whether one should use an objective measure for what is purulent etc!
criterion b under superficial is also problematic – how does one ever get ‘aseptically-obtained’ samples from a superficial incision? wound swabs presumably not ok but I would guess are used

Would be very interested to know of how people teach surveillance staff to apply the NHSN definition, esp for sternotomies , where essentially the superficial wound is extremely close to the deep sternal structure , and also for prosthetic joints where similar problems of distinguishing the depth of infection arise

thanks
John

Dr John Ferguson
Director, Infection Prevention & Control, Hunter New England Health
Locked Bag 1, Newcastle Mail Centre, NSW 2310
Tel 61 2 4921 4444 | Fax 61 2 4921 4440 | Mob +61 428 885 573 | john.ferguson@hnehealth.nsw.gov.au | http://www.hicsiganz.org
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