As acute critical-care surgery evolves, it is imperative to introduce reliable devices that can intraoperatively assess a patient's cardiovascular functions. Owing to the fact that traditional methods are usually invasive, non- or less-invasive innovations have attracted the attention of clinicians in recent decades. The FloTrac system monitors cardiovascular performance by analyzing peripheral arterial waveforms and a preset database, and it decreases the invasiveness by using a pulmonary arterial catheter. The reliability of cardiac output measurements was confirmed in many critically ill subjects in cardiac surgeries and intensive care units. Moreover, the FloTrac system is easy to set up, and interpreting the information is simple. The FloTrac system also provides a useful preload predictor, that is, stroke volume variation (SVV), for fluid management, which has been proven to enhance surgical safety in the treatment of critically ill patients. Goal-directed therapy guided by SVV and other hemodynamic variables was advocated for peri-operative fluid optimization. Although the evolution of each updated algorithm of the FloTrac system has demonstrated improved accuracy and limited shortcomings, the latest third-generation algorithm is still not equal to the gold standard reference. The accuracy of the latest third-generation algorithm is controversial in septic conditions, and its use is still unacceptable in liver transplantation. Due to vasoactive challenges, especially in the administration of norepinephrine, a conclusion could not be reached. Clinicians should recognize the appropriate uses and limitations when using the algorithm during acute critical surgeries.