Hemodynamik

Hemodynamics is the study of blood flow and the forces that govern circulation. It covers the pressure, flow, and resistance within the cardiovascular system, including both systemic and pulmonary circulation. The aim is to understand how the heart, blood vessels, and blood properties combine to determine tissue perfusion and oxygen delivery.

Core concepts include the relationship between flow (Q), pressure difference (ΔP) and vascular resistance (R): Q = ΔP / R. The arterial pressure gradient drives flow, while resistance depends mainly on vessel radius, length, and blood viscosity. Key hemodynamic components are preload (venous return to the heart), afterload (resistance the ventricle must overcome), contractility, and vascular compliance. Cardiac output, the product of heart rate and stroke volume, is a central determinant of tissue oxygen delivery. Mean arterial pressure reflects average driving pressure, and systemic vascular resistance represents the tone of the arterial tree.

Measurement methods range from invasive to noninvasive. Invasive monitoring includes central or right heart catheterization for cardiac output (thermodilution or Fick principle) and wedge pressures, as well as arterial lines for continuous blood pressure. Noninvasive approaches include echocardiography, Doppler ultrasound, impedance cardiography, and peripheral pulse contour analysis.

Clinical relevance is broad. Hemodynamics are routinely assessed in shock, heart failure, perioperative care, and sepsis to guide therapies such as fluids, vasopressors, inotropes, and other interventions. Proper management aims to maintain adequate tissue perfusion and oxygen delivery, while avoiding edema or ischemia due to maldistribution of flow.