Poor adoption of hemodynamic optimization during major surgery: are we practicing substandard care?

Hemodynamic optimization of surgical patients during the perioperative period aims to improve outcomes. This is frequently referred to as goaldirected therapy (GDT), a term that has been used for nearly 30 years to describe methods of optimizing fluid and hemodynamic status. Unfortunately, the term has never been standardized, and therefore can mean different things to different people, causing a significant amount of confusion. It can refer to supramaximal oxygen delivery using a pulmonary artery catheter (PAC), early treatment of sepsis in the emergency department, or perioperative optimization of fluid status, all different goals directing different therapies. It could be said that we all practice a form of GDT intraoperatively every day, except that our goals are normally related to arterial blood pressure (BP), heart rate, and occasionally central venous pressure (CVP). These are all known to be poor indicators of intravascular volume and cardiac output (CO). In healthy volunteers, heart rate and BP remain relatively unchanged despite a 25% hemorrhage of blood volume. One systematic review showed that CVP is unable to identify which patients need more fluid, and concluded that CVP should no longer be routinely measured in the intensive care unit, operating room, or emergency department. This leads to a key question: Can monitoring of stroke volume (SV) and CO improve our ability to optimize fluid and hemodynamic status? This issue of Anesthesia & Analgesia includes 2 excellent systematic reviews by Hamilton et al. and Gurgel and do Nascimento on hemodynamic optimization of patients undergoing major surgery. The authors avoided the term GDT, and instead described the techniques as “preemptive hemodynamic intervention” and “optimizing tissue perfusion. ” It is clear that the reviews examined the same subject, with 26 studies (of 29 and 31, respectively) common to both articles. Perioperative hemodynamic optimization was first described in the 1980s, when the PAC was used to guide fluid and inotrope administration. This enabled clinicians to augment tissue oxygen delivery to supranormal levels (DO2 600 mL/min/m ) in high-risk surgery patients, the target being based on earlier work by Shoemaker et al. observing survivors after high-risk surgery. As both systematic reviews have shown, oxygen-targeted approaches were generally successful, and when mortality in high-risk surgery was approaching 20%, most studies were able to show a survival benefit. Despite these promising results, the technique was not widely adopted. Oxygen-targeted approaches required significant resources, were very labor intensive, and most importantly were reliant on information from the PAC. Catheterization of the right heart began falling out of favor in intensive care units in the 1990s after the publication of several observational studies showing increased mortality. Because early GDT was linked so closely with the use of PACs, it became embroiled in this controversy. The last 20 years have seen the arrival of a number of minimally invasive CO technologies such as esophageal Doppler, arterial pressure waveform analysis devices providing SV variation (SVV) and pulse pressure variation (PPV), and monitors based on bioimpedance and bioreactance technology. This has enabled clinicians to monitor and optimize SV, SVV, CO, and other hemodynamic variables without the need for a PAC. These monitors are easy to operate and minimally invasive, so they have gained wider use than PAC optimization in high-risk patients. They are also frequently used in patients undergoing major but not necessarily high-risk surgery, for example, elective abdominal surgery, extensive cancer surgery, hip arthroplasty, or major spinal surgery. Hemodynamic optimization in this patient population can usually be obtained by optimization of preload alone. The change in SV, SVV, or CO in response to a fluid challenge is used to assess volume responsiveness. When a patient is hypovolemic, an IV fluid challenge will typically result in a 10% increase in SV or CO, or a reduction in SVV. This patient has “recruitable” SV and is in a fluid-responsive state. In the perioperative setting, fluid challenges should be considered until the SV no longer increases by 10% and preload has been optimized. SVV and PPV alone have also been shown to be superior to static indices in predicting From the Department of Anesthesiology, Duke University Medical Center, Durham, North Carolina. Accepted for publication February 28, 2011. Conflict of Interest: See Disclosures at the end of the article. Reprints will not be available from the authors. Address correspondence to Tong J. Gan, MD, MHS, FRCA, Department of Anesthesiology, Duke University Medical Center, Box 3094, Durham, NC 27710. Address e-mail to tjgan@duke.edu. Copyright © 2011 International Anesthesia Research Society DOI: 10.1213/ANE.0b013e318218cc4f