Autonomic nervous system dysfunction in critically ill cancer patients: Hemodynamic consequences and multimodal assessment strategies

In critically ill cancer patients, autonomic nervous system (ANS) dysfunction may contribute to hemodynamic instability and organ dysfunction and may be exacerbated by malignancy-related injury and anticancer treatment. This narrative review summarizes conventional methods for assessing ANS function, including heart rate variability (HRV), blood pressure variability (BPV), baroreflex sensitivity (BRS), and cardiovascular autonomic reflex testing, together with emerging approaches such as high-resolution multimodal monitoring (MMM) and artificial intelligence (AI). Host-organ unregulated response (HOUR) framework is used to integrate interactions among autonomic, neuroendocrine, inflammatory, immune, coagulation, metabolic, bioenergetic, and microcirculatory dysregulation. Collectively, these approaches may facilitate real-time assessment of autonomic function and tissue perfusion, thereby supporting risk stratification and individualized management in critically ill cancer patients.