Cumulative Intra-Abdominal Pressure Burden and Acute Kidney Injury After Emergency Abdominal Surgery

Intra-abdominal pressure varies during postoperative critical illness. Individual measurements and peak values may not fully characterize sustained or recurrent pressure elevation. Evaluating cumulative exposure may provide additional information about the relationship between abdominal pressure and postoperative renal dysfunction. This single-center prospective observational cohort study will examine serial intra-abdominal pressure measurements obtained in a surgical intensive care unit after emergency abdominal surgery. Pressure will be measured using a standardized intravesical technique. Cumulative intra-abdominal pressure burden will be derived from repeated measurements, incorporating both the magnitude and duration of pressure elevation. Mean arterial pressure will be recorded alongside intra-abdominal pressure to characterize the accompanying hemodynamic conditions. Abdominal perfusion pressure will be calculated as mean arterial pressure minus intra-abdominal pressure. These measurements will allow abdominal pressure exposure to be evaluated in the context of systemic pressure and abdominal perfusion. Clinical data will include baseline renal function, illness severity, operative characteristics, fluid balance, and vasopressor use. Multivariable analyses will assess the association between cumulative pressure burden and acute kidney injury while accounting for relevant clinical factors. The predictive performance of cumulative exposure measures will also be compared with that of individual pressure measurements. The study is observational. Clinical management will follow established practice, and treatment decisions will remain the responsibility of the attending clinicians.