Use of Negative Pressure Wound Therapy in High Risk Surgical Closed Incisions

Wound infections continue to be a common and costly problem after surgery. Surgical site
infections (SSIs) are the second most common type of health care - associated infections
(HAI), occurring in 2% to 5% of patients undergoing surgery in the United States. This
percentage corresponds to approximately 300,000 to 500,000 surgical site infections (SSIs)
estimated to occur each year.

Most SSIs that do not involve implants are diagnosed within 3 weeks post--operatively . SSIs
lead to increased hospital stay, cost, and risk of death. The cost attributable to SSI range
from $3,000 to $29,000 per SSI per patient depending on the type of operation; thus, the
total annual cost approximately reaches the $10 billions. On other analyses documented
nearly 1 million additional inpatient-days and $1.6 billion in excess costs , as well as up
to twice the costs of a patient without SSI. Moreover, SSIs increase mortality risk by 2 to
11 fold 11, while the 77% of deaths in patients with SSI are attributed directly to the
SSIs. Several organizations have put forth guidelines for definition and recommendations to
decrease their incidence. Attempts have been made to stratify patients into various
categories on the basis of the type of surgical procedure and risk factors the patients
have, including diabetes, malnutrition, and hypoxemia. These systems have been used to
develop criteria for the prevention of wound infection.

Appropriate timing and dosing of antibiotics, type of skin preparation, temperature of the
patient in the operating room, blood oxygen level of the patient during surgery, and
management of blood glucose levels all have been standardized in an attempt to decrease
wound infection rates . In addition, debridement of all tissue that may contribute to wound
infection, particularly ischemic skin and subcutaneous tissue, is standard surgical
procedure. Standardization has led to a small decrease in incidence but has not led to a
significant reduction in the overall rate. One reason for this is the multifactorial nature
of SSI development. Factors regarding patients and pre-operative status, operative
procedures and intra-operative events, as well as postoperative course, all need to be
addressed, and there is not a complete understanding of their range and impact. What is
known is that at the time of wound closure, one needs a minimal number of bacteria in the
wound, and the wound itself must be reasonably well perfused and oxygenated. After surgery,
wound perfusion and oxygenation are evaluated by clinical appearance. If the wound does not
appear ischemic, it is assumed that perfusion and oxygenation are adequate. Unfortunately,
this has never been quantified. Negative-pressure wound therapy (NPWT) has been used to
speed the healing of open wounds.

How this occurs is not completely understood, but increased generation of granulation tissue
at the margins of the open wound implies increased generation of blood vessels and
substances needed to promote wound healing.

The theory of negative pressure is the stimulation of wound healing on the basis of improved
perfusion to the wound. This has been seen in open wounds and has recently been applied to
closed surgical wounds thought to be at high risk for infection. Negative-pressure wound
therapy was also applied to closed wounds in an attempt to improve wound perfusion and
oxygenation, which in theory would eliminate these two variables from the wound infection
equation.

Techniques - Procedures Complete closure of the abdominal wall and skin follows the
completion of the index surgical procedure. Closed suction drains may be used at the time of
skin closure in any patient who requires skin flap elevation to attain skin closure. Skin
closure will be accomplished with dermal sutures and / or staples. Wound coverage will be
done with the NPWT Prevena ™ Incision Management System (Kinetic Concepts Inc, San Antonio,
TX). The application of the NPWT will be done as per manufacturer's instructions of use. The
application of continuous negative pressure will be applied at 125 mm Hg.Antibiotics will be
given to all patients. The post-operative use of antibiotics in the clearcontaminated and
contaminated cases will be 24-hour of prophylactic administration. The post-operative use of
antibiotics for the dirty (infected) cases will be of therapeutic administration, as
clinically indicated. In infected patients, cultures will be taken at the time of the index
procedure, and the antibiotic treatment will be targeted to the culture results. Wounds will
be assessed every 48 hours by dressing changes, and also at the time of final dressing
removal and at 2 and 4 weeks after surgery. The dressing removal will take place at
discharge OR at 5 - 7 post-operative days OR if clinically indicated, whichever comes first.
Post-discharge follow-up The patients will be followed-up per routine at the surgical
clinic. At 2 and 4 weeks after the date of the operation a formal evaluation will take
place. Both evaluations must be in person at the surgical clinic.

Inclusion Criteria:

- All five of the following criteria must be present for enrollment into the study:

1. Signed written informed consent must be provided by the patient or by patient's
legally acceptable representative, if patient unable to consent. In the case of
penetrating abdominal trauma, and only in the case of penetrating abdominal
trauma, the patient or surrogate will have less than 24 hours to decide and sign
consent due to the nature of the condition and situation.

2. Age > 18 years

3. Abdominal operation entering the peritoneal cavity under general anesthesia for
colostomy reversal OR excision of a pilonidal sinus OR after penetrating
abdominal trauma.

4. Clean - contaminated OR contaminated OR dirty wound (as defined by Wound
Infection Surveillance) OR use of skin flaps for skin closure.

5. Complete closure of the surgical wound including the skin.

Exclusion Criteria:

- 1) Known allergic reaction at the wound dressing parts of the Prevena ™ Incision
Management System.

(Included but not limited to: sensitivity to silver, allergic or hypersensitivity reaction
to acrylic adhesives).

2) Inability to close the abdominal wall at the index procedure. 3) Inability to close the
skin at the index procedure. 4) Patients under 18 years old. 5) Pregnant women test