State-of-the-art review: ß-blockade in critical illness.

Critical illness is characterised by activation of the sympathetic nervous system which plays an important adaptive role in maintaining cardiovascular stability and organ perfusion. However, excessive sustained adrenergic stimulation may become maladaptive, contributing to tachyarrhythmias, myocardial injury, immune dysregulation, metabolic derangements, and organ dysfunction. This state-of-the-art review evaluates the role of ß-blocker therapy as a potential strategy to modulate or counteract the adrenergic response in critically ill patients. Current data suggest that their use remains highly context-dependent and controversial. There are established benefits in selected scenarios, including acute myocardial infarction, tachyarrhythmias, hypertensive emergencies, thyroid storm, and prevention of variceal bleeds. In contrast, evidence is limited or conflicting in septic shock, traumatic brain injury, acute heart failure, burns and other critical care syndromes. Concerns include impairment of compensatory cardiovascular responses, reduction of cardiac output, hypotension, and compromised organ perfusion. Furthermore, the safety and efficacy of ß-blockade appear to depend on the type and dose of ß-blocker, patient phenotype, timing of initiation, hemodynamic reserve, and whether therapy represents continuation of chronic treatment, withdrawal and re-initiation, or de novo initiation during acute illness. This review highlights major gaps in knowledge, including the absence of reliable indicators to identify patients most likely to benefit, uncertainty regarding optimal treatment targets and monitoring strategies, and limited randomised evidence in heterogeneous ICU populations. A phenotype-driven, physiology-guided approach that accounts for hemodynamic status, sympathetic spectrum and timing of ß-blocker therapy is likely required to optimise outcomes.