Arterial Stiffness During Negative Pressure Wound Therapy for Abdominal Wall Wounds

WALLAS is a small observational study of 30 adults with complex wounds in the abdominal wall after surgery. All participants will receive negative pressure wound therapy (NPWT) because their treating team considers it appropriate. This treatment uses a sealed dressing connected to a suction device. The study will not decide which treatment participants receive or change their usual care. The main aim is to find out how the stiffness of the large arteries changes during treatment. Researchers will also examine whether larger reductions in wound size and inflammation are linked to larger reductions in artery stiffness. An upper-arm cuff device will estimate artery stiffness by measuring how quickly pressure waves travel along the aorta, the body's main artery. Measurements are planned before treatment starts, around day 5, and when the first course of NPWT ends. Blood pressure will be taken into account when interpreting the results. During planned dressing changes, researchers will record wound depth and, when safe and technically possible, measure the wound cavity using sterile saline. Photographs will document the wound. Results from routine blood tests will provide information about inflammation; no extra blood samples are required for research. Wound recovery and further treatment will be followed for about six months after NPWT starts. The study will also assess how practical and safe the measurement procedures are. Because there is no comparison group, it cannot determine whether NPWT itself causes any changes in artery stiffness.

Inclusion Criteria: * Age 18 years or older. * Clinically indicated negative pressure wound therapy (NPWT) for a postoperative abdominal wall wound complication. * At least one predefined complexity feature: mesh infection or exposure, purulent drainage, a deep wound cavity, tunneling, undermining, or fascial dehiscence after source control with protected viscera. * Hemodynamic stability sufficient for arterial stiffness measurement. * Written informed consent. * Willingness to undergo serial study assessments. There is no minimum wound surface-area threshold. The term "major" is an operational study definition, not an externally validated severity category. Following emergency surgery, enrollment is permitted only after source control and once the patient is stable for repeated vascular assessment. Exclusion Criteria: * NPWT for a non-abdominal wall wound. * NPWT primarily for temporary open-abdomen management. * Active uncontrolled bleeding. * Untreated osteomyelitis in the wound region. * Malignant wound bed. * Unprotected major vessel or exposed organ. * Uncontrolled intra-abdominal sepsis. * Severe hemodynamic instability or vasopressor requirement. * A fixed bilateral upper-arm contraindication to cuff-based oscillometric measurement present before enrollment. * Inability or unwillingness to provide informed consent. Fascial dehiscence may be included after source control when viscera are protected and NPWT targets the abdominal wall wound rather than temporary open-abdomen closure. Failure to obtain interpretable arterial stiffness recordings after enrollment is documented in descriptive feasibility reporting and is not used as a post hoc exclusion criterion.