【用戶】周庭彣
【年級】大一下
【評論內容】大對流(Bulk convection)人體正常通氣的整個過程可以用“大對流”來形容。(The whole of normal human ventilation can be described as "bulk convection".)大對流的定義是一群分子通過其他分子介質的運動。(The definition of bulk convection is the movement of a group of molecules through a medium of other molecules. )簡而言之，就是潮氣量，即通過病患實際進出的氣體。(In short, this is tidal volume, the actual entry and exit of gas through the patient.)在 HFOV 中，“潮氣量”可以忽略不計，大對流的表現為：當氧氣被肺泡吸收時，仍持續夾帶新鮮氣體。(In HFOV, where the "tidal volume" is negligible, bulk convection is represented by the continual entrainment of fresh gas, as oxygen is absorbed in the alveolus. )持續去除氣體導致壓力降低，為更多的氣體騰出空間。(The decreased pressure generated by continual gas removal makes space for more gas.) 同軸流(Coaxial Flow)靠近管壁的氣體比管內中心的氣體流動得更慢。(Gas on the outside of a tube flows more slowly than the gas positioned centrally inside the tube.)因此，在 HFOV ，實際可能存在雙向氣流------即使管內中心的氣體沿著吸氣方向移動，但靠近管壁的氣體則是沿著呼氣方向移動。(Because of this, in HFOV there may actually be a bi-directional flow of gas, with the gas on the outside moving in the expiratory direction even while the central gas moves in the inspiratory direction.) 泰勒氏分散(Taylor dispersion)這是一個複雜的概念，基本上描述受到剪切力的物質，擴散率會增加。(This is a complicated concept, which essentially describes the increase in the diffusivity of a substance that is subjected to shear forces. )振盪器向前推動，導致一股新鮮的含氧氣體被向下推到氣道中心；(The forward push of the oscillator results in a jet of fresh oxygenated gas which is pushed down the center of the airway;)然後，這種射流，擴散到支氣管周圍的氣體中，使其富含氧氣。(this jet then diffuses into the gas at the periphery of the bronchi, enriching it with oxygen.) 鐘擺效應(Pendelluft)這個奇怪的德語單詞，描述氣體從一些肺泡進入其他肺泡的運動。(This strange German word describes the movement of gas from some alveoli into other alveoli.) 基本上，它是肺單位之間的氣體交換。(Basically, it is the exchange of gas between lung units.)當某些鄰近區域的肺泡順應性非常不同時，就會發生這種情況；(This happens when some neighboring regions have very different compliance;)它們的時間常數會不同，當一個肺泡正在坍塌而另一個仍肺泡保持打開狀態時，它們會相互“吹”氣。(their time constants will differ and they will "blow" gas into each other when one is collapsing and the other still remains open.)一些工程師能夠在具有可調節“支氣管”直徑的氣道分叉模型中證明這一機制。(Some engineers were able to demonstrate the mechanics of this in a model of airway bifurcation with adjustable "bronchial" diameter.)https://derangedphysiology.com/main/required-reading/respiratory-medicine-and-ventilation/Chapter%205.1.8/physiology-gas-exchange-hfov