Fluid Responsiveness in Passive Leg Raising

One of the most important concerns in critical care is ensuring the patient receives the correct amount of fluid; either too much or too little can have adverse effects. Unfortunately, however, clinical assessment of fluid responsiveness (FR) can be challenging for the reason that invasive monitoring (if not mechanical ventilation) may be the most effective measure for continued appraisal. Extensive research has been performed in recent years regarding the most proficient medical procedure to address FR. For the purposes of this assignment, we will review ten studies that offer a variety of findings regarding fluid responsiveness and the practice of passive leg raising. Let us preface this review with an acknowledgment that there are a number of issues that must be factored into FR, and require a more sophisticated measure of patient fluid needs than the fifty-fifty indication offered by such quick assessments as the historically utilized central venous pressure method to guide fluid therapy in hospitalized patients. In fact, one study noted that is one example of point of care testing that has been increasingly debunked in recent years as nothing short of flawed. Moreover, all indications are that clinical decision making of fluid management should not rely on this unreliable measurement tool at all. However, the facile act of passive leg raising does appear to be successful in a variety of medical scenarios. 

For example, in our first study “Nonspecific hemodynamic “maximization,” based on predetermined hemodynamic targets, was originally proposed 20 years ago for improving survival in high-risk surgery patients” (Benomar, Ouattara, Estagnasic, Brusset, and Squara, 2010, p. 1875). According to their examination, fluid responsiveness (FR) is most often defined as a change of cardiac output (CO); and the most accurate predictor of reversibility is a passive leg raising test. The purpose of the research was specifically to study the feasibility of predicting fluid responsiveness (FR) by passive leg raising (PLR) using a Bioreactance-based noninvasive cardiac output monitoring device (NICOM). The results were based on findings from 75 patients in two separate centers, and specific to this subset of subjects In this specific population of patients, the researchers concluded that it was clinically valid to use PLR as a predictor of FR. Another expert in the subject of passive leg raise tests to address fluid responsiveness is Monnet who has led a group of researchers through several studies on this specific medical area of concern. In one study performed in the setting of an intensive care unit the doctors set out to test if pulse pressure variation could be a predictor of fluid responsiveness specific to acute respiratory distress and shallow lung compliance; while reviewing the cardiac sonography and considering the cardiac index induced by passive leg-raising and by an end-expiratory occlusion test. The driving concern, in this case, was “patients with acute respiratory distress syndrome (ARDS), because excessive fluid overload is deleterious and because a restrictive fluid strategy might be preferable in this context” (Monnet, Bleibtreu, Ferré, Dres, Gharbi, Richard, and Teboul, 2012, p.153).  Their conclusions were enlightening on the matter – if not altogether what they had predicted. The group reported that ‘the ability of pulse pressure variation to predict fluid responsiveness was inversely related to compliance of the respiratory system, and that pulse pressure variation became less accurate for predicting fluid responsiveness. Yet, they still endorsed the passive leg-raising test as valuable in such cases. It is evident that FR and PLR have been a driving concern of Monnet and his associates for some time; witness to the fact that they performed and reported on a similar test conducted back in 2006. In this case the experimental group consisted of 71 mechanically ventilated patients of which 31 had arrhythmias. Their objective was to use Passive leg raising (PLR) to predict fluid response. They wanted to learn if this could be useful in place of respiratory variation of stroke volume, and they hypothesized that the hemodynamic response to PLR would be an adequate predictor of fluid responsiveness with this type of patient. In this case the parameters of the study were uniquely different than their later one; in part because “they allowed the attending physician to decide whether or not to perform a fluid challenge based on the presence of at least one clinical sign of inadequate tissue perfusion as a result of the absence of contraindication for fluid infusion” (Monnet, Rienzo, Osman, Anguel, Richard, Pinsky, and Teboul, 2006, p. 1404). Succinctly, they concluded that changes in aortic blood flow induced by PLR predict preload responsiveness in ventilated patients; albeit arrhythmia patients poorly predict preload responsiveness. 

A second group of researchers also undertook multiple studies that incorporated a summation of the results of a meta-analysis of previous clinical studies. In the first review, nine articles were considered that included a total of 353 patients. The specific purpose was to systematically analyze evidence of the ability of passive leg raising-induced changes predict fluid responsiveness. The findings, although not comprehensive by any means, are still heartening for physicians who believe PLR to be an adequate medical response to FR. “Passive leg raising-induced changes in cardiac output reliably predict fluid responsiveness regardless of ventilation mode, underlying cardiac rhythm and technique of measurement and can be recommended for routine assessment of fluid responsiveness in the majority of ICU population. PLR-induced changes in pulse pressure can be a viable alternative with lower predictive ability (Cavallaro, Sandroni, Marano, La Torre, Mannocci, De Waure, Bello, Mavigli and Antonelli, 2010, p. 1483). Cavallaro, along with a group of colleagues, had actually considered FR and PLR in a previous study conducted in 2008 with a group of 41 patients who had experienced a shock and were subsequently sedated and medically ventilated. They were specifically concerned with the effects of passive leg raising (PLR) on hemodynamics and on cardiac function according to the preload dependency that had been defined by the superior vena cava collapsibility index. As noted elsewhere in this essay passive leg raising (PLR) is a reversible fluid-loading maneuver that has the potential to increase blood volume by shifting venous blood from the legs toward the thorax. Among the interesting results of this study was the conclusion that “different mechanisms can contribute to the hemodynamic changes observed during PLR including an increase in systemic venous return that induces an increase in cardiac output in preload-dependent patients. Too, the results are applicable only to sedated patients adapted to their ventilator. How sympathetic stimulation or cardiac reflexes may alter the hemodynamic response to PLR is unknown in awake and spontaneously breathing patients”  (Cavallaro, Sandroni, & Antonelli, 2008, p. 135). The setting for the next study was two separate university ICUs and included in this research were thirty-nine patients with acute circulatory failure who were receiving mechanical ventilation and had a pulmonary artery catheter in place. The aim of the physicians was to determine if and the extent that passive leg raising (PLR) had in inducing changes in the arterial pulse pressure and it was an effective predictor of rapid fluid loading (RFL) in patients who were specifically suffering from acute circulatory failure and had mechanical ventilation support. In short, the researchers were able to conclude that “the response to RFL could be predicted noninvasively with this simple observation technique in which changes in pulse pressure were evident during PLR in patients with acute circulatory failure who were receiving mechanical ventilation”  (Boulain, Achard, Teboul, Richard, Perrotin, & Ginies, 2002, p.1251). 

In one of two targeted studies that sought to uncover more specific findings through a singular application of the purported connection between FR and PLR; the study begins with a reiteration of previous claims. That being that passive leg raising (PLR) is a simple reversible maneuver that mimics rapid fluid loading and increases cardiac preload; effectively allowing for testing of fluid responsiveness with accuracy in spontaneously breathing patients. In this case, however, the patient population was limited to “thirty-four patients with spontaneous breathing activity. Measurements of stroke volume were obtained with transthoracic echocardiography (SV-TTE) and with the Vigileo™ (SV-Flotrac) in a semi-recumbent position, during PLR and after volume expansion (500 ml saline)” (Biais, Vidil, Sarrabay, Cottenceau, Revel,1 and Sztark, 2009, p. 195). The results were more than a little encouraging. According to the findings “PLR-induced changes in SV-Flotrac are able to predict the response to volume expansion in spontaneously breathing patients without vasoactive support”.  The final two studies reviewed for this essay both limited their research parameters to hemodynamic effects of passive leg raising on shock patients. In one case, forty patients with shock, sedated and mechanically ventilated, were included on whom transesophageal echocardiography was performed. Researchers concluded that “hemodynamic changes related to PLR were only induced by increased cardiac preload” (Caille, Jabot, Belliard,  Charron,  Jardin, & Vieillard, 2008, p. 1244). 

As our final study made note “Rapid fluid loading is standard treatment for hypovolemia but because volume expansion does not always improve hemodynamic status, predictive parameters of fluid responsiveness are needed. Passive leg raising is a reversible maneuver that mimics rapid volume expansion by inducing changes in stroke volume. Surrogates are reliable predictive indices of volume expansion responsiveness for mechanically ventilated patients” (Préau, Saulnier, Dewavrin, Florent, Durocher, & Chagnon, 2010, p.820). In this study 34 patients were included, but the study group was limited to patient with severe sepsis and acute pancreatitis. Their results confirm what we have found repeatedly in this essay – PLR is effective in FR.  

References

Benomar, B., Ouattara, A., Estagnasie, P., Brusset, A., & Squara, P. (2010). Fluid responsiveness predicted by noninvasive bioreactance-based passive leg raise test. Intensive Care Medicine, 36(11), 1875-1881. doi:10.1007/s00134-010-1990-6

Biais, M., Vidil, L., Sarrabay, P., Cottenceau, V., Revel, P., & Sztark, F. (2009). Changes in stroke volume induced by passive leg raising in spontaneously breathing patients: Comparison between echocardiography and Vigileo/FloTrac device. Critical Care,13(6), R195-R195. doi:10.1186/cc8195

Boulain, T., Achard, J., Teboul, J., Richard, C., Perrotin, D., & Ginies, G. (2002). Changes in BP induced by passive leg raising predict response to fluid loading in critically ill patients. Chest, 121(4), 1245-1252. doi:10.1378/chest.121.4.1245

Brun, C., Zieleskiewicz, L., Textoris, J., Muller, L., Bellefleur, J., Antonini, F., et al. (2012). Prediction of fluid responsiveness in severe preeclamptic patients with oliguria. Intensive Care Medicine, doi:10.1007/s00134-012-2770-2

Caille, V., Jabot, J., Belliard, G., Charron, C., Jardin, F., & Vieillard Baron, A. (2008). Hemodynamic effects of passive leg raising: An echocardiographic study in patients with shock. Intensive Care Medicine, 34(7), 1239-1245. doi:10.1007/s00134-008-1067-y

Cavallaro, F., Sandroni, C., & Antonelli, M. (2008). Functional hemodynamic monitoring and dynamic indices of fluid responsiveness. Minerva Anestesiologica, 74(4), 123-135.

Cavallaro, F., Sandroni, C., Marano, C., La Torre, G., Mannocci, A., De Waure, C., et al. (2010). Diagnostic accuracy of passive leg raising for prediction of fluid responsiveness in adults: Systematic review and meta-analysis of clinical studies. Intensive Care Medicine, 36(9), 1475-1483. doi:10.1007/s00134-010-1929-y

Monnet, X., Bleibtreu, A., FerrÃ, A., Dres, M., Gharbi, R., Richard, C., et al. (2012). Passive leg-raising and end-expiratory occlusion tests perform better than pulse pressure variation in patients with low respiratory system compliance. Critical Care Medicine, 40(1), 152-157. doi:10.1097/CCM.0b013e31822f08d7

Monnet, X., Rienzo, M., Osman, D., Anguel, N., Richard, C., Pinsky, M., et al. (2006). Passive leg raising predicts fluid responsiveness in the critically ill. Critical Care Medicine, 34(5), 1402-1407. doi:10.1097/01.CCM.0000215453.11735.06

PrÃau, S., Saulnier, F., Dewavrin, F., Durocher, A., & Chagnon, J. (2010). Passive leg raising is predictive of fluid responsiveness in spontaneously breathing patients with severe sepsis or acute pancreatitis. Critical Care Medicine, 38(3), 819-825. doi:10.1097/CCM.0b013e3181c8fe7a