FloTrac/Vigileo system monitoring in acute-care surgery: current and future trends

Abstract

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.

Keywords::

• cardiac output
• FloTrac system
• fluid responsiveness
• less invasiveness
• stroke volume variation
• third generation

Financial & competing interests disclosure

Y-F Tsai, F-C Liu and H-P Yu are employees of the Anesthesiology Department, Chang Gung Memorial Hospital, Taoyuan, Taiwan. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

No writing assistance was utilized in the production of this manuscript.

Key issues

• • Peri-operative and post-operative complications and mortality can be significantly reduced by adopting cardiac output (CO) measuring devices for guiding fluid management. Although many promising devices for arterial pressure-based CO measurements have been approved for clinical practice, they are not yet equal to the gold standard method, which is intermittent thermodilution through a pulmonary arterial catheter (PAC). The development of more precise and reliable devices for use in acute critical surgery is a key focus of innovations. Reducing invasiveness and offering valuable parameters should increase safety during operations and decrease the occurrence of morbidity and mortality.

• • The main purpose of the third-generation algorithm is to refine the inaccuracy of the second-generation device for CO measurements in hyperdynamic or vasoplegic patients, especially in patients with sepsis and liver transplantation. However, the third-generation device has failed validation in liver transplant surgery and some septic researches. Until now, the majority of published studies on this latest version have focused on its weakness, that is, application in highly selected populations or those with vigorously altering vascular tone; most studies have demonstrated its unreliability in these conditions. These findings may lead to some biases and may not be representative as a whole. This limited amount of research renders it difficult to decide whether the newer FloTrac algorithm can be precisely used in major surgeries.

• • We believe that the third-generation algorithm preserves the inherited accuracy of the second-generation algorithm in already proven settings, such as in patients who underwent cardiac surgeries or who received post-operative care in intensive care units. We need additional confirmation to demonstrate whether the upgrades for hyperdynamic conditions may have reduced its original reliability.

• • Stroke volume variation is supported by several studies to be a simple and dependable indicator that enables clinicians to make decisions on a patient’s volume status. According to the recommended cutoff value, treatment of patients through a goal-directed fluid optimization protocol is advocated to reduce morbidity. The easy use of the device simplifies the treatment of critically ill patients; however, there are some limitations.

• • There are no ideal CO measuring devices. Which device is the most suitable depends on the individual patient’s conditions. We must evaluate indications, limitations, invasiveness, difficulties and details regarding the set-up and benefit/cost ratio.

• • The standard method (intermittent thermodilution technique) commonly referenced is biased as 3–30%, and the rigid application of the ±30% cutoff for the percentage error is questionable without reporting the precisions of both methods separately.

Notes