Predicting Fluid REsponsiveness Using Superior Vena Cava Collapsibility IndEx duriNg High-risk Non-Cardiac surgEry (PRESCIENCE)

Patients undergoing high-risk non-cardiac surgery, including acute laparotomies and open aortic surgery, are at high risk of postoperative complications and adverse cardiovascular events. Perioperative fluid therapy is a factor which is strongly associated with postoperative outcomes. To avoid both hypovolemia and excessive fluid administration a strategy of goal-directed fluid therapy (GDFT) has been coined. Traditionally in the setting of operating rooms GDFT relied on stroke-volume variation (SVV) measured by hemodynamic monitors, based on uncalibrated pulse contour cardiac output analysis (uAPCO). However in the described cohort of patients uAPCO methods show a significantly increased measurement error, which is mainly attributed to dynamic changes in peripheral vascular tone. Furthermore, frequent occurrence of arhytmias in those patients limits the use of SVV and all other dynamic indices of fluid responsiveness based on those methods. Superior vena cava collapsibility index (SVC-CI) is a parameter which is devoid of the above mentioned limitations. It relies on respiratory variation of superior vena cava during the respiratory cycle and is therefore reliable in patients with irregular heart rhytm and seems independent from changing afterload conditions.

The main purpose of this study is to validate SVC-CI in patients undergoing controlled mechanical ventilation during laparotomies and during open aortic surgery, with focus on elevated PEEP levels and aortic cross-clamping.