Preoperative Dynamic Assessment of Cardiac Reserve in Patients Following Abdominal Aortic Surgery. A Probability Analysis

In order to estimate cardiac reserve preoperatively the authors studied 33 con secutive patients aged forty-four to eighty-one years (mean ± SD, 67.2 ± 7.3) scheduled for elective infrarenal abdominal aortic surgery. All patients had pul monary artery catheters inserted on the morning of surgery and had Starling curves constructed by plotting of the rate of change in cardiac output against the rate of change in pulmonary artery wedge pressure (PAWP) with a specific volume loading protocol. The slope of the curve and the PAWP, which cor responded to the maximum cardiac output (PAWPmax), were carefully noted in each patient. A deliberate effort was made perioperatively to maintain each patient on the upslope of the curve and not to exceed their estimated PAWP max. Four patients developed a major postoperative cardiac complication and 1 patient died. All complications occurred in patients with a Starling slope of < 0.035 (p = 0.0003). By utilization of this slope in a derived probability model the authors could accurately and quantitatively predict which patients were at greatest risk of developing a postoperative cardiac complication following ab dominal aortic surgery.