Passive leg raising for fluid responsiveness in children: Is it reliable?

Abstract

Intravenous fluid administration is an integral part of management for critically ill children with impaired perfusion. Loss of more than 15–20% of intravascular volume impairs the preload which in turn results in decreased cardiac output, clinically manifesting with signs of impaired perfusion or shock. In children, major causes of shock, such as diarrhea, hemorrhage, sepsis, or anaphylaxis, result in either actual or relative intravascular hypovolemia (due to vasodilation). Rapid administration of fluid bolus could augment preload to improve the cardiac output and, thus, can potentially reverse shock. However, studies demonstrate that only half of the patients are preload responsive. In the other half, this fluid accumulates and leaks into the interstitial space of almost all organs and can result in serious adverse effects. Fluid leak is exacerbated in inflammatory states such as sepsis; and about 95% of the given fluid leaks out within 1 hour even among the fluid responders, thus limiting the beneficial effect.1 Hence, to identify which patient would respond to fluid bolus, tests of fluid responsiveness are recommended. Static parameters such as heart rate, systolic blood pressure, central venous pressure, and pulmonary artery occlusion pressure are the points of assessments and are poor predictors of fluid responsiveness. Dynamic parameters are based on heart–lung interaction and are proven to be reliable. Some of the common dynamic parameters are: • Pulse pressure variation • Stroke volume variation • Pulse plethysmographic index • Changes in aortic or carotid blood flow velocity with respiration • Changes in inferior vena cava diameter with respiration • Ventilator maneuvers such as end expiratory occlusion, tidal volume challenge • Fluid challenge such as passive leg raising test (PLR) or mini fluid bolus.