Hemodynamisk

Hemodynamics is the study of blood flow and the forces that shape circulation. It covers how the heart generates flow, how blood moves through the vascular system, and how pressures and resistances determine tissue perfusion. The core variables include cardiac output, heart rate, stroke volume, arterial pressure, venous pressure, and systemic vascular resistance. A common way to conceptualize flow is through an analogy to Ohm’s law: Flow equals the pressure gradient divided by resistance (Flow = ΔP / R). Cardiac output is the volume ejected by the heart per minute and is the product of heart rate and stroke volume. Systemic vascular resistance reflects arterial tone and influences mean arterial pressure. Preload refers to ventricular filling pressure, afterload to the pressure the heart must overcome to eject blood, and contractility to the heart muscle’s intrinsic ability to contract.

Monitoring methods range from invasive techniques, such as arterial lines and pulmonary artery catheters, to noninvasive approaches like echocardiography and Doppler ultrasound. Dynamic indices, including pulse pressure variation, can help guide fluid therapy in appropriately monitored patients.

Clinically, hemodynamics inform the assessment of shock, heart failure, and critical illness, guiding fluid management, vasopressor and inotropic support, and therapy titration to maintain adequate tissue perfusion and oxygen delivery. Abnormal hemodynamics may result from hypovolemia, ventricular dysfunction, systemic vasodilation, or vascular collapse, with treatment aiming to optimize pressure, flow, and oxygen delivery to tissues.