Fluid Therapy in Critically Ill Patients From Liberal Resuscitation to Precision Hemodynamic Management

Abstract

Abstract

Background: Intravenous fluid therapy is among the most frequently administered yet least rigorously prescribed interventions in critical care. Historically guided by tradition and fixed-volume protocols, fluid resuscitation has long been associated with the unintended consequences of fluid overload, including organ dysfunction and increased mortality. A paradigm shift toward individualized, physiology-guided fluid management has emerged over the past two decades, driven by accumulating trial evidence and advances in hemodynamic monitoring.

Objective: To review the evolution of fluid resuscitation practice in critically ill patients, examine landmark trial evidence reshaping current practice, appraise dynamic tools for assessing fluid responsiveness, and outline a precision framework for fluid administration, titration, and de-escalation across the phases of critical illness.

Evidence Review: Major randomized controlled trials and consensus guidelines were reviewed, including the SMART, SALT-ED, PLUS, SAFE, CHEST, SPLIT, and CLASSIC trials, alongside Surviving Sepsis Campaign and European Society of Intensive Care Medicine recommendations. The physiological basis of fluid responsiveness, the limitations of static preload markers, and the clinical utility of dynamic indices, including passive leg raising, pulse pressure variation, stroke volume variation, and point-of-care echocardiography, are discussed. Conceptual frameworks including the Four D's of fluid therapy and the ROSE model are appraised as structured approaches to individualized management.

Results: Balanced crystalloids are associated with reduced rates of acute kidney injury and renal replacement therapy compared with normal saline, though the magnitude of benefit varies across populations. Hydroxyethyl starches are definitively contraindicated in critical illness. Albumin demonstrates equivalence to saline in heterogeneous ICU populations with selective benefit in septic and cirrhotic physiology. Fluid overload is established as an independent driver of pulmonary, renal, and microcirculatory injury. The CLASSIC trial supports the safety of a restrictive fluid strategy beyond the initial resuscitation phase. Dynamic indices of fluid responsiveness consistently outperform static preload markers in predicting hemodynamic benefit from fluid administration.

Conclusions: Fluid therapy in critical illness must be approached with the same rigor applied to any pharmacological intervention, with explicit indications, individualized dosing, active reassessment, and planned de-escalation. No protocol or biomarker substitutes for bedside clinical judgement informed by dynamic hemodynamic assessment. Emerging technologies including artificial intelligence-assisted monitoring and closed-loop systems hold promise for further personalization, but the central task of modern intensive care remains physiological titration rather than volume maximization or minimization.