Cardiopulmonary point-of-care ultrasound for critical care.

Point-of-care ultrasound (POCUS) has emerged as an essential bedside tool for the rapid assessment and management of critically ill patients. This review outlines the evolution of POCUS from a focused, rule-in/rule-out modality to an advanced, integrative diagnostic approach capable of supporting complex haemodynamic evaluation. Technological advances, including handheld devices and artificial intelligence, have enhanced accessibility, diagnostic accuracy, and training efficiency. In the intensive care setting, echocardiographic interpretation must be contextualised within dynamic physiological variables such as preload, ventilation, vasoactive support, and metabolic status. POCUS plays a pivotal role in differentiating shock phenotypes-cardiogenic, distributive, hypovolemic, and obstructive-by integrating structural and functional cardiac assessment with lung and systemic venous ultrasound findings. Key haemodynamic parameters, including left ventricular outflow tract velocity time integral (LVOT VTI) and Doppler-derived indices, enable evaluation of cardiac output and fluid responsiveness, while dynamic tests such as passive leg raising further refine management decisions. The review also highlights the role of POCUS in assessing hypoxaemia through combined cardiopulmonary evaluation and introduces the "POCUS pyramid" framework, integrating cardiac, pulmonary, and venous domains into a unified physiological model. Ultimately, when performed by appropriately trained clinicians, POCUS and critical care echocardiography enhance diagnostic precision, guide therapy, and improve bedside decision-making while recognising inherent limitations and the need for structured training and governance.