1. Blood flow depends on critical closing pressure (Pcrit). 2. Vascular waterfall model emphasizes flow's independence from downstream pressure. 3. Perfusion relies on arterial pressure exceeding Pcrit. 4. Pcrit can be estimated indirectly via pressure-flow relationships. 5. Vasoplegic shock lowers Pcrit, affecting autoregulation. 6. Elevated PEEP decreases venous return and pulmonary blood flow. 7. Interventions must consider arterial pressure and Pcrit to be effective.