Objectives: Intra-abdominal hypertension (IAH) is an increasingly recognized disorder, and its diagnosis depends on accurate pressure monitoring. Bladder-based protocols are favored, but are not always clinically feasible. Abdominal venous (i.e. vena cava) pressure measurements are an alternative but are logistically challenging. We hypothesized that for patients suffering acute kidney injury, transducers built into renal replacement therapy (RRT) machines offer a simple opportunity to monitor pressures using catheters inserted via femoral veins.
Design: We performed in vitro testing of the accuracy of pressure transducers incorporated into continuous RRT devices, using highly calibrated instrumentation in the IAH-relevant range of 0 to +50 mmHg. We developed a protocol for using this modality in vivo, by stopping all pumps so as to allow equilibration of pressures: clinical application in a patient with femoral vein catheters and IAH was then described.
Results: In vitro analyses showed accuracy of the extracorporeal pressure transducers with an r² of 0.998, p < 0.001. In the patient case, the pressure transduced at the RRT device was identical to those obtained from bladder catheters. IAH also led to access recirculation and ineffective therapy.
Conclusions: Pressure sensors incorporated into continuous RRT machines can be accurate in the IAH physiologic range, and thus may be used to easily measure intra-abdominal pressure via appropriate-length femoral vein-inserted access catheters. If not relieved, IAH can be an under-appreciated cause of access recirculation and ineffective clearance for any RRT modality (continuous or intermittent) using femoral catheters.