A Prospective Observational Study of the Use of Negative Pressure Wound 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.