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Fluid Resuscitation: Perioperative Optimization of the High-Risk Patient

　　Elliott Bennett-Guerrero, MD,[1] of Columbia University College of Physicians and Surgeons, New York, NY, discussed the perioperative optimization of the high-risk patient. Hypovolemia is difficult to diagnose clinically, especially in the high-risk patient requiring invasive procedures such as the insertion of the pulmonary artery catheter (PAC). Volume optimization can be achieved with either colloid or crystalloid fluid, but there is no consensus on quantity and timing. There are considerable differences among the various studies dealing with perioperative optimization: the patient population (elective surgery vs septic shock), the use of a monitoring device (such as the PAC), the application or not of a goal-directed therapy algorithm, and the administration of fluids alone or with the addition of a vasopressor. All of these differences should be kept in mind when comparing these studies.
　　There have been several goal-directed therapy trials using fluid plus a vasoactive agent so far, with the article by Shoemaker and colleagues being one of the first. Of note is that all these studies refer to high-risk patients undergoing nonemergency surgery and not to septic patients in the intensive care unit (ICU) requiring surgery. By using fluid and dopexamine and by increasing oxygen delivery for high-risk surgery, Boyd and coworkers[2] were able to demonstrate a 14.3% (P = .015) drop in mortality. Wilson and associates[3] randomized 138 high-risk patients undergoing major elective surgery to receive either standard care or additional vasoactive agents (adrenaline or dopexamine) to increase oxygen delivery. A decrease in mortality by 14% (P = .007) was also demonstrated. Lobo and colleagues[4] conducted a similar study that had to be interrupted because of the significant difference in 60-day mortality between the treatment and the control group (50% vs 15.7%, P < .05). In contrast, the study by Takala and coworkers[5] of 412 patients undergoing major abdominal surgery demonstrated that dopexamine did affect mortality when compared with fluids alone. Sandham and colleagues[6] found no benefit to therapy directed by PAC in high-risk surgical patients requiring intensive care. This was a multicenter study involving 1994 surgical patients that had no explicit algorithm. Intrahospital mortality of the control group was also lower than expected, and there was no mention of the amount of intraoperative fluid used.
　　Other studies have tested fluid administration without the addition of a vasoactive agent. The stroke volume was estimated (invasively or not), and boluses of fluids were given until the stroke volume reached its maximum. In these studies, administration of volume was not based on hemodynamic instability, thus avoiding the intraoperative dips in blood pressure or urine output.
Proximal femoral fracture repair constitutes surgery in a high-risk population. Intraoperative intravascular volume loading to optimal stroke volume resulted in a more rapid postoperative recovery and a significantly reduced hospital stay.[7]
　　Another similar study, by Venn and associates,[8] demonstrated that invasive intraoperative hemodynamic monitoring with fluid challenges during repair of femoral fracture shortens length of hospital stay.
　　A meta-analysis of studies dealing with perioperative global blood flow to explicit goals is under review. Preliminary results suggest the beneficial effect of this strategy on survival. Of note is the fact that this review does not take into account studies not stating explicit goals, like the study by Sandham and colleagues.[6]
　　Dr. Bennett-Guerrero concluded that there are considerable differences among various studies dealing with perioperative optimization, and the negative studies might be explained by the lack of a firm algorithm. There appears to be growing evidence that optimal fluid administration is the main cause of an improved outcome.