Ultrafiltration in the critically ill patient: a framework for personalized care.

Area of Science:

• Critical Care Medicine
• Nephrology
• Cardiovascular Physiology

Background:

• Fluid overload is prevalent in critically ill patients post-resuscitation, correlating with adverse outcomes.
• Ultrafiltration (UF) is a key intervention for fluid overload, but optimal parameters and safety limits are not well-defined.
• Current understanding of UF intolerance is limited, often oversimplifying it to volume depletion and neglecting complex physiological responses.

Purpose of the Study:

• To synthesize the physiological effects of UF and cardiovascular responses.
• To reframe UF intolerance as a multidimensional construct involving four compensatory axes.
• To propose a novel framework for proactive, individualized UF prescriptions based on patient endotypes.

Main Methods:

• Literature synthesis of physiological effects and cardiovascular responses to UF.
• Conceptual framework development for UF intolerance based on four compensatory axes.
• Identification of dynamic predictors and bedside endotypes for UF intolerance.

Main Results:

• UF intolerance is multifactorial, influenced by vascular refilling, cardiac response, venoconstriction, and systemic arteriolar resistance.
• Critical illness and RRT factors impair these compensatory axes, leading to hypoperfusion.
• Proposed endotypes of UF intolerance include preload dependence, cardiac dysfunction, decreased vascular tone, autonomic dysfunction, and impaired vascular refilling.

Conclusions:

• A proactive, individualized UF strategy is crucial, moving beyond a one-size-fits-all approach.
• Dynamic predictors and bedside endotypes can guide tailored UF prescriptions.
• A physiology-based, preventive approach using dynamic testing and monitoring may enhance hemodynamic tolerance and decongestion efficacy.