Hypovolaemia and tissue hypoperfusion can pass undetected during and after major surgery. The resulting systemic inflammatory response and organ dysfunction, often not clinically apparent for several days, may lead to increased morbidity and mortality and prolonged hospital stay.

In this regard, intraoperative optimization of circulatory status by volume loading has been shown to improve the outcome of patients undergoing high-risk surgery. Indeed, several reports (1-7) have shown that monitoring and maximizing stroke volume by volume loading (until stroke volume reaches a plateau, actually the plateau of the Frank-Starling curve) during high-risk surgery decreases the incidence of post-operative complications and the length of hospital stay. Unfortunately, this strategy has required so far the measurement of stroke volume by a cardiac output monitor, as well as a specific training period for the operators (8), and hence is not applicable in many institutions as well as in many countries.

The arterial pulse pressure variation (∆PP) induced by mechanical ventilation is known to be a very accurate predictor of fluid responsiveness, i.e. of the position on the preload/stroke volume relationship (Frank-Starling curve) (9).

By increasing cardiac preload, volume loading induces a rightward shift on the preload/stroke volume relationship and hence a decrease in ∆PP. Patients who have reached the plateau of the Frank-Starling relationship can be identified as patients in whom ∆PP is low (9).

Therefore, the clinical and intraoperative goal of “maximizing stroke volume by volume loading” can be achieved simply by minimizing ∆PP.

We designed the present study to investigate whether monitoring and minimizing ∆PP by volume loading during high-risk surgery may improve post-operative outcome and decrease the duration of post-operative hospital stay.