Context-sensitive fluid therapy in critical illness

Abstract

Microcirculatory alterations are frequently observed in critically ill patients undergoing major surgery and those who suffer from trauma or sepsis. Despite the need for adequate fluid administration to restore microcirculation, there is no consensus regarding optimal fluid therapy for these patients. The recent recognition of the importance of the endothelial glycocalyx layer in capillary fluid and solute exchange has largely changed our views on fluid therapy in critical illness. Given that disease status largely differs among critically ill patients, fluid therapy must not be considered generally, but rather tailored to the clinical condition of each patient. This review outlines the current understanding of context-sensitive volume expansion by fluid solutions and considers its clinical implications for critically ill patients. The modulation of capillary hydrostatic pressure through the appropriate use of vasopressors may increase the effectiveness of fluid infusion and thereby reduce detrimental effects resulting from excessive fluid administration.

The protective effect of hydroxyethyl starch solution on the glycocalyx layer in an acute hemorrhage mouse model

“…Because this study focused on the effect of rapid fluid resuscitation in the early stage of massive hemorrhage, we set the blood withdrawal volume to 1.5 mL, which is considered life-threatening blood loss for a mouse whose whole blood volume is around 2.5 mL. In this severe hypovolemic situation, most resuscitation fluid, which is rapidly infused, would remain in the intravascular space due to context-sensitive effects [39], at least during the early stage of massive hemorrhage. Furthermore, based on the blood volume of a mouse, we considered that rapid fluid resuscitation with volumes 1.5-fold higher than the volume of blood removed can lead to right ventricular failure.…”

A pilot study evaluating adaptive closed‐loop fluid resuscitation during states of absolute and relative hypovolemia in dogs

“…In conclusion, an adaptive C‐L fluid administration system based on a compartmental model of fluid distribution computed an infusion rate to drive an endpoint of resuscitation (eg, SVV) during both absolute (controlled or uncontrolled), relative hypovolemia, or a combination of relative hypovolemia and absolute controlled hypovolemia. Fluid rates and volumes delivered approximated values recommended by studies that have modeled different fluid rates and volumes required to restore and maintain blood volume after acute hemorrhage . The proposed adaptive control framework did not require subject‐specific information (eg, age, gender, weight, diagnosis).…”

“…The response to fluid administration can vary significantly between patients and even within the same patient due to various disease processes or general anesthesia; this variability may result in under‐ or over‐resuscitation . Over‐resuscitation can produce fluid overload resulting in cardiac and pulmonary complications, emphasizing the importance of judicious, controlled, and context sensitive IV fluid administration …”

Recent advances in the understanding of endothelial barrier function and fluid therapy

“…Also, in states with low capillary hydrostatic pressure (eg, anaesthesia, hypovolaemia and sepsis), the increase in Pc with fluid infusion is limited. Hence, a higher proportion of fluid remains intravascular 31. In contrast, if the baseline Pc is already high (eg, volume overload), fluid infusion will cause its further increase, thereby limiting intravascular volume expansion.…”