Search results
Results From The WOW.Com Content Network
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 ...
An area with ventilation but no perfusion (and thus a V/Q undefined though approaching infinity) is termed "dead space". [6] Of note, few conditions constitute "pure" shunt or dead space as they would be incompatible with life, and thus the term V/Q mismatch is more appropriate for conditions in between these two extremes.
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.
Total dead space (also known as physiological dead space) is the sum of the anatomical dead space and the alveolar dead space. Benefits do accrue to a seemingly wasteful design for ventilation that includes dead space. [1] Carbon dioxide is retained, making a bicarbonate-buffered blood and interstitium possible.
Hypoxemia is generally attributed to one of four processes: hypoventilation, shunt (right to left), diffusion limitation, and ventilation/perfusion (V A /Q) inequality. [1] Moreover, there are also "extrapulmonary" factors that can contribute to fluctuations in arterial PO 2 .
Ventilation–perfusion coupling is the relationship between ventilation and perfusion in the respiratory and cardiovascular systems. [1] Ventilation is the movement of air in and out of the lungs during breathing. [2] Perfusion is the process of pulmonary blood circulation, which reoxygenates blood, allowing it to transport oxygen to body tissues.
The partial pressure of oxygen (pO 2) in the pulmonary alveoli is required to calculate both the alveolar-arterial gradient of oxygen and the amount of right-to-left cardiac shunt, which are both clinically useful quantities. However, it is not practical to take a sample of gas from the alveoli in order to directly measure the partial pressure ...
The partial pressure of carbon dioxide, along with the pH, can be used to differentiate between metabolic acidosis, metabolic alkalosis, respiratory acidosis, and respiratory alkalosis. Hypoventilation exists when the ratio of carbon dioxide production to alveolar ventilation increases above normal values – greater than 45mmHg.