Mechanical ventilation is a cornerstone of critical care, yet conventional positive-pressure ventilation (PPV) can induce significant and often detrimental hemodynamic consequences, primarily through its effects on intrathoracic pressure. Biphasic Cuirass Ventilation (BCV), a modern form of noninvasive negative pressure ventilation, offers a fundamentally different approach to respiratory support. By cyclically applying negative and then positive pressure to the chest and upper abdomen, BCV mimics physiological breathing more closely, generating a negative intrathoracic pressure during inspiration. This chapter provides a comprehensive review of the hemodynamic effects of BCV. We explore the core principles of cardiopulmonary interaction, contrasting the adverse effects of PPV—namely reduced preload and increased right ventricular afterload—with the unique profile of BCV. The primary hemodynamic benefit of BCV is its ability to augment venous return and cardiac preload by lowering right atrial pressure, effectively functioning as a noninvasive cardiac assist device. This leads to an increase in stroke volume and cardiac output, particularly in patients with preload-dependent states or compromised cardiac function. We will dissect the effects on right and left ventricular afterload, overall cardiac performance, and systemic perfusion. Clinical evidence from studies in cardiogenic shock, postcardiac surgery, and advanced heart failure will be reviewed to illustrate these physiological principles in practice. Finally, the chapter addresses the limitations and future directions for this promising technology, positioning BCV not merely as a ventilator but as an integrated cardiopulmonary support system.