Perfusion and aortic surgery: patient directed cardiopulmonary bypass and quality improvement

Aortic surgery frequently extends the boundaries of perfusion knowledge learned from non aortic cardiac surgery.This is due to the extremes of temperature, prolonged bypass times, hypothermic arrest, and selective organ(s) perfusion. Suboptimal perfusion can potentially affect outcomes even after technically successful aortic surgery. We present the concepts of patient directed bypass with regard to blood pressure, flow-during cardiopulmonary bypass (CPB), oxygen delivery, cooling, and carbon dioxide levels on bypass. Quality of perfusion during aortic surgery is then addressed in the context of Perfusion Standards of Reporting Trials (PERFSORT, www.perfsort.net). PERFSORT analyses these variables during bypass: blood pressure, hematocrit, lactate, glucose, and temperature, all of which are known to affect outcomes. PERFSORT can be applied to individual cases or a series, and although primarily designed for research publications, is equally useful in a purely clinical setting. A new concept from engineering called Lissajous figures is then discussed to potentially retrospectively assess the effects of ischemia during aortic surgery. This may help identify why some patients despite flawless surgery, anesthesia, and perfusion, in the absence of bleeding, stroke, and obvious causes of organ damage at the time of aortic surgery develop multi organ dysfunction.