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The Shunt equation (also known as the Berggren equation) quantifies the extent to which venous blood bypasses oxygenation in the capillaries of the lung.. “Shunt” and “dead space“ are terms used to describe conditions where either blood flow or ventilation do not interact with each other in the lung, as they should for efficient gas exchange to take place.
A pulmonary shunt is the passage of deoxygenated blood from the right side of the heart to the left without participation in gas exchange in the pulmonary capillaries. It is a pathological condition that results when the alveoli of parts of the lungs are perfused with blood as normal, but ventilation (the supply of air) fails to supply the perfused region.
Factors that can increase the D LCO include polycythaemia, asthma (can also have normal D LCO) and increased pulmonary blood volume as occurs in exercise.Other factors are left to right intracardiac shunting, mild left heart failure (increased blood volume) and alveolar hemorrhage (increased blood available for which CO does not have to cross a barrier to enter).
This might have been caused by blood clotting, heart failure, pulmonary emphysema, or damage in alveolar capillaries. [12] Diagram of pulmonary shunt in alveoli and pulmonary capillary. Secondly, the pulmonary shunt is caused by zero or low V/Q ratio due to insufficient ventilation and excess perfusion. Improper ventilation lowers blood ...
The Bohr equation is used to measure physiological dead space. Unfortunately, the concentration of carbon dioxide (CO 2 ) in alveoli is required to use the equation but this is not a single value as the ventilation-perfusion ratio is different in different lung units both in health and in disease.
Pulmonary function testing is a diagnostic and management tool used for a variety of reasons, such as: Diagnose lung disease. Monitor the effect of chronic diseases like asthma, chronic obstructive lung disease, or cystic fibrosis. Detect early changes in lung function. Identify narrowing in the airways. Evaluate airway bronchodilator reactivity.
Diffusing capacity of the lung (D L) (also known as transfer factor) measures the transfer of gas from air in the lung, to the red blood cells in lung blood vessels. It is part of a comprehensive series of pulmonary function tests to determine the overall ability of the lung to transport gas into and out of the blood.
The impact of gravity on pulmonary perfusion expresses itself as the hydrostatic pressure of the blood passing through the branches of the pulmonary artery in order to reach the apical and basal areas of the lungs, acting synergistically with the pressure developed by the right ventricle. Thus at the apex of the lung the resulting pressure can ...