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Mechanical dead space or external dead space is volume in the passages of a breathing apparatus in which the breathing gas flows in both directions as the user breathes in and out, causing the last exhaled gas to be immediately inhaled on the next breath, increasing the necessary tidal volume and respiratory effort to get the same amount of ...
The Bohr equation, named after Danish physician Christian Bohr (1855–1911), describes the amount of physiological dead space in a person's lungs. This is given as a ratio of dead space to tidal volume. It differs from anatomical dead space as measured by Fowler's method as it includes alveolar dead space.
Minute ventilation (or respiratory minute volume or minute volume) is the volume of gas inhaled (inhaled minute volume) or exhaled (exhaled minute volume) from a person's lungs per minute. It is an important parameter in respiratory medicine due to its relationship with blood carbon dioxide levels. It can be measured with devices such as a ...
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.
Dead space refers to the volume not taking part in gas exchange. [11] Alveolar dead space and insufficient perfusion result in a V/Q ratio above 0.8 with decreased fresh oxygen in the alveoli. [ 1 ] This might have been caused by blood clotting , heart failure , pulmonary emphysema , or damage in alveolar capillaries .
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 ...
Physiological dead space is the volume of ventilated gas that does not reach parts of the lung in which gas exchange occurs. [19] Breathing apparatus usually add some mechanical dead space to increase the total dead space of the system of breathing apparatus and user.
The dead space can be determined from this curve by drawing a vertical line down the curve such that the areas below the curve (left of the line) and above the curve (right of the line) are equal. Most people with a normal distribution of airways resistances will reduce their expired end-tidal nitrogen concentrations to less than 2.5% within ...