Critical closing pressure in the circulation : Understanding the vascular waterfall phenomenon
This review explores the historical development, physiological foundations, clinical implications, and future directions of the vascular waterfall model in critical care.
Key points :
• Arterial pressure, vasomotor tone, and tissue forces define Pcrit as a dynamic flow-limiting threshold.
• Conrad’s collapsible tube experiments explain nonlinear resistance and oscillatory flow beyond Starling resistor models.
• When Pcrit exceeds Pv, regional autoregulation and flow redistribution occur, making tissue perfusion downstream-independent.
• Vasoplegia lowers Pcrit, abolishes waterfall and impairs autoregulation, supporting vasopressors’ role to restore DPcrit–Pmsf.
• The vascular waterfall explains RV afterload changes due to alveolar/pleural pressure shifts during mechanical ventilation.
