Negative pressure wound management system for inguinal wounds after venous hybrid procedures

Annually about 1-2 per 1000 people in Western European countries develop deep
venous thrombosis (DVT). The most frequent long-term complication of DVT is
development of a Post thrombotic syndrome (PTS). (1)
PTS consists of a range of symptoms that can occur in patients following a deep
vein
thrombosis. The definition of PTS is difficult to quantify but can be measured
best by the Villalta score. The higher the Villalta score, the more severe
complaints are. A score >15 indicates a severe PTS.
The pathological pathway of PTS is not completely understood but can be found
in altered haemodynamics. Virchow*s triad consisting of hypercoagulable state,
vascular wall damage and venous stasis explains the development of a deep vein
thrombosis. The first two mentioned causes are encountered in standardised
treatment nowadays. For the venous stasis no good treatment existed until
recently percutaneous angioplasty (PTA) and dedicated venous stents became
available. (2)
Patients with PTS experience symptoms related to chronic venous insufficiency
caused by obstruction and valve impairment leading to venous hypertension.
These symptoms may include pain, tired legs, venous claudication and cramps,
oedema, pigmentation or other skin changes finally leading to ulcera.
Patients with established PTS experience a significant impact on QoL with, in
several cases,
daily disabilities comparable to an impaired QoL in Chronic Obstrucive
Pulmonary Disease (COPD), congestive heart disease and diabetes. (3, 4)
PTS develops in 40-50 % of all patients with a history of a DVT depending on
anatomic position of deep venous thrombosis and involvement of collateral
system.(5-7) Whenever DVT occurs in iliofemoral or caval veins with obstruction
of collateral systems the outflow obstruction is greater than DVT*s in the calf
veins. One can understand this outflow obstruction will present more clinical
and invalidating symptoms. Other risk factors for severe PTS, found in a large
prospective trial, are morbidity included severity of venous symptoms at 1
month, recurrent ipsilateral DVT, high body mass index and higher age. Some of
these risk factors are modifiable while others are not. (8, 9)
Venous outflow obstruction is caused by inadequate recanalization,
extravascular compression or congenital abnormalities.
Conventional treatment of DVO to minimalize complaints consists of the use of
elastic compressions stockings, exercise, lymph drainage therapy and the use of
(pain) medication. For most patients the physician selects one or a combination
of the treatment modalities mentioned above in an attempt to reduce symptoms.
However this is not always effective.(10)
A definitive solution for DVO patients may be a revascularisation procedure and
stenting of
the affected tract. This can be achieved by endovascular or hybrid procedures
in which a
PTA is performed and a dedicated venous stent is placed. This procedure is
already being performed in various hospitals around the world with good results
on an individual basis. The goal of PTA and stenting is to prevent PTS
(whenever placed in acute settings) or recurrent DVT and associated expected
decrease in quality of life.
Patients with a severe PTS with extension of post thrombotic changes (stenosis
or occlusion) below the sapheno-femoral junction sometimes require a so-called
hybrid procedure. Because of the difficulty in predict which patients need this
so-called procedure we sometimes experience occlusion of stents in patients
treated solely by percutaneous recanalization and stent placement. This second
group will have to be hospitalized to receive urokinase by thrombolysis and
afterwards creation of an AV-fistula to maintain flow through the previously
stented traject.
This procedure is performed under general anesthesia in which recanalization
and stenting is performed and a possible endoflebectomy with creation of
arterio-venous fistula (AVF) will be created to guarantee preferential and
significant flow. The vein is opened in a longitudinal way and the synechiae
and scars will be removed. Afterwards the vein will be sutured primairily or
with a patch to guarantee an acceptable diameter of the vessel. Because of the
idiopatic damage at the vessel there is an increased risk of thrombogenetic
events and all of these patients receive an AVF. This AVF is created by
connecting the common femoral vein to the common femoral artery with a PTFE
loop of 5-6 mm. (11)
To gain access to the femoral vein and artery, a longitudinal groin incision of
5-10 cm has to be made. This will result in restriction of daily activities
during a couple of weeks. The main reason can be found in the fact that the
incision will be made in a mobile area. Besides this, patients with venous
obstruction mostly have impaired lymphatic drainage.
Our experience is that venous patients have important postoperative morbidity
because of leakage of seroma and possible infections associated with this.
In our own population, currently consisting of 86 patients treated by the
aforementioned hybrid procedure have a surgical site infection rate of 35% and
lymph leakage of 27%.
Hereby 4.7 % (4 patients) of our own population had an additional surgical
procedure because infection proceeded and gave an infection of the PTFE
AV-fistula. In this additional surgical procedure the fistula needed to be
removed with the chance of occlusion of the stents.
In order to reduce these numbers, untill now, patients received a gentamycin
mesh and low-vacuum drain to drainage seroma. This drain is removed whenever
production of fluid is less than 50cc/ 24 hours.
To treat these patients more optimal and prevent infections and lymphatic
leakage we want to give all patients a negative pressure incision management
system (Prevena) during 7 days.

Thus, the rationale of this study is to assess the incidence of wound
infections and secondary lymph leakage in patients treated with venous hybrid
procedure and Prevena vacuum therapy.

Primary Objective:
Assess the incidence of wound infections in patients treated with venous
stenting and AV fistula and Prevena negative pressure wound therapy (NPWT).

Secondary Objective(s):
Assess the incidence of lymph leakage in patients treated with venous stenting
and AV fistula and Prevena NPWT.

Evaluate the clinical appearance and quality of the scar by filling out the
Patient Observer Scar Assessment Scale v2.0 Nl and photos

This is a cohort study in patients with deep venous obstruction after a venous
hybrid procedure (primary or secondary) to assess wound infection (and lymph
leakage rate) after treatment with negative pressure incision management
system. Subjects will visit the hospital with routine control moments and do
not have to make an additional visit for this study.
As in standard care all patients will be seen on the outward patient clinic
before treatment, after 1-2 weeks, 6 weeks, 3 months, 6 months and 12 months.
On the first visit (pre-operative) all patients undergo duplex ultrasound and
magnetic resonance venography as in standard care. The medical history,
allergies and medication use will be recorded. Special attention will be paid
to patients with prednisone because quality of skin and wound management is
altered in these patients. In medical history special attention will be paid to
diabetic disease, chronic obstructive pulmonary disease and collagen deficits
because of the known wound healing problems in these patients. Body mass index
and intoxications with especially smoking will be recorded. All of the above
mentioned parameters are already scored in standard care. If by chance one of
the factors of medical history is not scored, the general practitioner will be
asked to provide this after inclusion of the patient.
Whenever a patient has post thrombotic changes below the sapheno-femoral
confluents, a hybrid procedure is offered whenever complaints are severe. All
patients will be informed about the standard treatment and addition of the
negative pressure incision management system.
Whenever patients present after solely percutaneous recanalization and stenting
with occluded stents, a thrombolysis is offered whenever complaints are heavy.
If an additional AV-fistula is needed to guarantee stent flow these patients
will also be informed about the study of the NPWT.
All patients receive 1-2 gram Kefzol 30 minutes before incision like our
hospital policy explains. The hybrid procedure will be performed by
recanalization and stenting with additional endoflebectomy by a longitudinal
incision in the vein. The vein will be cleared and an arterio-venous fistula
will be created between the common iliac vein and common iliac artery by using
a PTFE loop. All patients have a gentamycin mesh and drain placement before
wound closure because of the large lymphatic and seroma leakage during the
first few days postoperative. Whenever drain production of the additional drain
is below 50cc/ 24 hours this drain will be removed.

The only addition to aforementioned standard treatment is the use of the
Prevena system. This will be placed on the operation theatre under sterile
conditions (after disinfection with chlorhexidin and possible shaving of the
inguinal area). The system will be placed on a closed inguinal wound. The
negative pressure incision management system will be installed with a negative
pressure of 120 mmHg during 7 days. Afterwards the first (out)ward patient
clinic follow up will take place and wound evaluation will be performed.
Whenever it is not possible to see the patient within 1 week the wound
management system will be asked to be removed by the general practitioner. This
is possible because the system is attached like a plaster. Patients will be
seen for their first postoperative visit within 2 weeks.
The goal of the study is to evaluate wound infections 3 months postoperative.
Evenso the evaluation of the Patient and Observer Scar Assessment scale. Photos
of the inguinal area will be taken at dismission, 7,15 and 30 days
postoperative.
Whenever there is system failure and the patient is experiencing wound problems
like redness, fever or purulent leakage oral antibiotic treatment will start.
Whenever redness will increase or fever will be continuous patients need to be
admitted to the hospital for intravenous antibiotic treatment like standard
care.

The Prevena system will be placed on the operation theatre like prescribed in
user manual.

All patients will receive the Prevena negative pressure incision management
system during 7 days postoperative. This system is used as a plaster with
negative pressure vacuum and has no negative side effects besides possible
errors in creating negative pressure or allergic reaction to ingredients of the
used products. Another minor possible negative effect can be the fact that
patients need to wear an extra (small) bag to save the canister. The advantage
is this canister is lightweight and portable.
Patients will meet routine follow up moments (like all of our treated patients
on 1-2 weeks, 6 weeks, 3 months, 6 months and 12 months postoperative) on the
outward patient clinic and no additional visits will be necessary. At
dismission, 7,15 and 30 days a photograph of the inguinal area will be taken.
Patients and physician will be asked to fill out the Patient Observer Scar
Assessment Scale v2.0 Nl on 3, 6 months and 12 months follow up to analyze the
quality and clinical appearance of the wound.