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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 ...
In respiratory physiology, the ventilation/perfusion ratio (V/Q ratio) is a ratio used to assess the efficiency and adequacy of the ventilation-perfusion coupling and thus the matching of two variables: V – ventilation – the air that reaches the alveoli; Q – perfusion – the blood that reaches the alveoli via the capillaries
Spirometry (meaning the measuring of breath) is the most common of the pulmonary function tests (PFTs). It measures lung function, specifically the amount (volume) and/or speed (flow) of air that can be inhaled and exhaled.
Ventilation rate (V) is the total gas volume that enters and leaves the alveoli in a given amount of time, commonly measured per minute. To calculate the ventilation rate, the tidal volume (inhaled or exhaled gas volume during normal breath) is multiplied by the frequency of breaths per minute, which is represented by the formula:
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.
The efficiency is a function of the total losses in the fan system, including aerodynamic losses in the fan, friction losses in the drive (e.g. belt), losses in the electric motor, and variable speed drive power electronics. For more insight into how to maximise energy efficiency and minimize noise in fan systems, see ref.1
When breathing surpasses normal ventilation rate, one has reached ventilatory threshold. For most people this threshold lies at exercise intensities between 50% and 75% of VO 2 max. A major factor affecting one's ventilatory threshold is their maximal ventilation (amount of air entering and exiting lungs).
Transtracheal jet ventilation refers to a type of high-frequency ventilation, low tidal volume ventilation provided via a laryngeal catheter by specialized ventilators that are usually only available in the operating room or intensive care unit. This procedure is occasionally employed in the operating room when a difficult airway is anticipated.