“Stretching” Negative Pressure Wound Therapy: Can Dressing Change Interval be Extended in Patients with Open Abdomens?
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Negative pressure wound therapy (NPWT) has evolved significantly since its humble beginnings as an improvised vacuum-based surgical wound dressing. Now viewed as a safe, patient- and provider-friendly, effective option in wound management, modern applications of NPWT include treatment of infected surgical wounds, traumatic wounds, open abdominal wounds, diabetic and pressure ulcers, wounds with exposed bone and hardware, burn wounds, and venous stasis ulcers.1 New applications for NPWT technology continue to evolve and understanding of NPWT dressing-tissue interactions is growing.2
The classic paradigm of NPWT dressing changes is based on the recommended interval of 48 hours in non-infected wounds3; however, whether NPWT dressings can be safely changed on a less frequent basis in this setting of non-infected wounds as well as open abdominal wounds has not yet been determined. Few clinical reports have examined this question (many of them indirectly).4-8 This preliminary report evaluates the interval between NPWT dressing changes among 60 patients with open abdominal (OA) wounds and assesses its potential effect on outcomes.
Materials and Methods
A retrospective database was created using chart review data from all patients with open abdomens (OA) at St. Luke’s Regional Trauma Center (a member of the University of Pennsylvania Trauma Network) from September 2001 to January 2006. The data were abstracted by single investigator and included demographics (age and gender), primary diagnoses at the time of laparotomy, surgical techniques utilized, types of wound closure, complications associated with OA, observed 28-day mortality, and complications involving enteric fistula, abscess, enteric leak, pressure ulceration, and deep venous thrombosis (DVT).
Calculated parameters included Simplified Acute Physiology Score (SAPS II) and predicted 28-day mortality9; the former was utilized because of its applicability to both traumatic and non-traumatic etiologies and recorded at the time the patient was determined to need OA management. A recent comparison study of six prediction models among patients admitted to the intensive care unit demonstrated that SAPS II provided accurate overall mortality prediction.10
Resource utilization measurements included hospital length of stay (LOS) starting at the point of initiation of the OA approach to patient discharge or death and time to abdominal closure, as well as procedures per patient and the average number of days between procedures until abdominal closure.
All patients were managed according to a previously published treatment algorithm for OA patients.11 In the immediate postoperative period, all patients underwent NPWT. Two NPWT techniques were commonly employed according to surgeon preference: 1) polyethylene-covered surgical towel with suction drains layered above the towel and covered with an impervious adhesive drape or 2) a commercially prepared sponge device (V.A.C.® System, KCI USA, San Antonio, Tex).
All patients underwent re-exploration within 6 to 48 hours depending on clinical stability. When possible, a tension-free primary fascial closure was performed at that time – such closure performed within 24 hours of the initial surgery was termed early delayed primary closure (DPC). If patients continued to manifest clinical characteristics that obviated abdominal closure (eg, continued bleeding, bowel or retroperitoneal edema, gross contamination), NPWT was continued. Primary fascial closure within 7 days utilizing NPWT was termed DPC with NPWT.
Patients using prolonged NPWT (>7 days) were re-evaluated after definitive operative therapy and physiologic restoration was complete.