Title: Back to Basics Series: Deciphering the Vent
题目：回到基础理论：解密机械通气
Author 作者: Haney Mallemat
翻译 ：于璐 何磊磊 校对： 陈都 肖锋
There are many ventilator modes to choose from, but almost every mode can be distilled down to its basic principles by understanding the “Three T's of Mechanical Ventilation”
有许多的呼吸机模式可以选择，但如果我们理解“机械通气的3个T”，几乎每一种模式都可以回原到它的基本原理。
Trigger: You must determine whether the vent or patient will trigger a mechanical breath. For example, machine-triggered breaths (a.k.a. control mode of ventilation) are used for paralyzed patients and will deliver a breath after a period of time has elapsed (e.g., if RR is 10/min, then a breath is given every 6 seconds). On the other hand, if a patient’s respiratory drive is intact (a.k.a. assist-mode) then the patient triggers the breath when the vent detects a patient induced change in airflow or airway pressure. These two modes can also be mixed together.
触发：你必须确定呼吸机或病人自己将触发机械呼吸。例如，机械触发呼吸（又名控制通气模式）是用于瘫痪的病人，在经过一定时间后它将提供一次呼吸（例如，如果呼吸频率设为10 次/分钟，那么将每6秒钟给一次呼吸）。另一方面，如果一个病人的呼吸驱动是完整的（即辅助呼吸模式），患者将通过呼吸机检测到其诱发的气流或气道压力改变而触发机械呼吸。这两种模式也可以混合在一起使用。
Target: Mechanical breaths must have a specific target, either a target airway pressure or a tidal volume. Because pressure and volume are directly related, pick the variable you want to target and the other parameter will vary depending on the patient’s intrinsic physiology. For example, if you choose to target a specific tidal volume, we may get one plateau pressure in a patient with normal lungs, but a higher plateau pressure in another patient with stiffer lungs.
目标：机械呼吸必须有一个特定的目标，这个目标不是气道压力就是潮气量。因为压力和容积有直接的关系，选择你想要的目标，另外一个参数的变化将取决于病人内在的生理条件。例如，如果你选择潮气量为特定目标，我们可以在一个肺功能正常的病人得到一个平台压，但在另一例肺组织较硬的患者得到一个较高的平台压力。
Terminate: You must decide when the mechanical breath (i.e., inspiration) terminates and expiration begins. Termination occurs: 1) after a set inspiratory time has elapsed in certain pressure-targeted modes, 2) when a predefined target volume has been achieved (i.e., volume-cycled modes), or 3) when airflow has been reduced by a certain percentage (as in pressure-support ventilation)
终止：你必须决定什么时候机械呼吸（如吸气）终止以和呼气开始。终止发生在：1）压控模式下一个设定的吸气时间过去后，2）当一个预定值的容量已经达到（如容控模式），或3）当气流已减少到一定的百分比（如压力支持通气）时。
Let’s put this all together by looking at an example: pressure control ventilation (rate = 12/min and target pressure 20cm H20).
让我们把这一切放在一起看一个例子：压力控制通气（呼吸频率= 12次 /分钟和目标压力20cm H20）。
Trigger: Because this is a “control”, not assist mode, the machine will trigger a breath 12 times per minute or every 5 seconds.
触发：因为这是一个“控制”，而不是支持模式，机器会每分钟给12次或每5秒给一次呼吸。
Target: Here we chose to have pressure be the target, so when the ventilator triggers a breath it will deliver a constant airway pressure of 20 cmH2O until we tell the vent terminate that breath.
目标：在这里，我们选择压力为目标，所以当呼吸机触发呼吸时它将提供一个恒定20 cmH2O气道压力，直到我们告诉它终止通气。
Terminate: the constant airway pressure will be turned off after a fixed period of time has elapsed; for this example we will set the inspiratory time as 1 second, then expiration begins.
终止：持续气道压力将在一个设定的时间过去之后关闭；比如在这个例子中我们将吸气时间设为1秒，然后呼气开始。
Now, after a few vent breaths we will observe the results of our settings and reassess; if the resulting tidal volume is lower than what we wanted, we will increase the target pressure to increase the tidal volume. If the tidal volume is higher than what we wanted, we will reduce the target pressure to reduce the tidal volume. We can also tweak the inspiratory time to manipulate the tidal volume, but this does so to a lesser degree.
现在，经过几次呼吸机通气，我们会观察我们设置的结果并进行评估；如果产生的潮气量低于我们想要的，我们将增加目标压力，从而增加潮气量。如果潮气量比我们想要的高，我们将减少目标压力，从而降低潮气量。我们还可以通过调整吸气时间来调整潮气量，但这只能在较小的范围内调节。
Try to break down your favorite modes of ventilation using the Three T’s and see if this helps you understand them better.
试试用这三个“T”来分解一下你喜欢的各种机械通气模式，看看这样做是不是可以帮助你更好地理解它们。