The Effects of Fluid Loading on Hemodynamic Changes and Right Ventricular Function with Aortic Unclamping During Abdominal Aortic Surgery

The authors investigated the effects of fluid loading on hemodynamic changes and right ventricular function (RVF) with aortic unclamping during abdominal aortic aneurysmal surgery in 12 patients. An ejection fraction volu metric pulmonary artery catheter was inserted through the right internal jugu lar vein to assess cardiac output and RVF with the use of an REF-1 computer. Anesthesia was maintained with a continuous infusion of sufentanil (0.5-1 μg/kg/hr), isoflurane (0.5-1%), and air/O 2 (FIO 2 = 0.5). Fluid loading with Ring er's lactate and 5% albumin was initiated ten to twenty minutes before aortic unclamping. Hemodynamic measurements and assessment of RVF were per formed ten to twenty minutes before and after aortic unclamping. Aortic un clamping after fluid loading decreased right ventricular end-diastolic and end-systolic volumes (RVEDV, RVESV) but increased right ventricular ejection fraction (RVEF) (p < 0.01). There were no significant changes in cardiac index (CI), stroke volume (SV), systemic vascular resistance (SVR), and cardic filling pressures: central venous pressure (CVP), and pulmonary capillary wedge pres sure (PCWP). There was a poor correlation between RVEDV and PCWP. The authors conclude that adequate fluid loading before aortic unclamping, esti mated by RVEDV, provided stable hemodynamic states (CI, SV, RVEF) follow ing aortic unclamping. Volume expansion following fluid loading can be better assessed by RVEDV than by cardiac filling pressures.