一個呼吸的距離

(引用自Uptodate-Overview of mechanical ventilation)

PEEP 

1. PEEP可以減少肺泡collapse。一開始我們可以用5cmH2O。如果遇到ARDS的病人，可以用超過20cm H2O。

2. 想當然爾，如果PEEP用高的話，可能會帶來副作用，例如前負荷下降(進而減少Cardiac output)，提高plateau airway pressure (使得barotrauma的機會上昇)，及大腦靜脈流出下降(會讓腦內壓上昇)。

Flow rate 

1. Peak flow rate到達60 L/min是必要的(連德正大夫說至少要40-50)。否則病人會覺得喘，出現不合邏輯的low peak inspiratory pressure及scalloping of the inspiratory pressure tracing

2. 需要高peak flow rate是在氣道阻塞性疾病合併acute呼吸酸。可以減少inspiratory time與增加expiratory time (縮小IE ratio)，也可以減少auto PEEP

3.缺點：增加peak airway pressure，減少 mean airway pressure -> 減少氧合。

Flow pattern

1. square wave (constant flow), a ramp wave (decelerating flow), and a sinusoidal wave

2. The ramp wave: more evenly than other patterns of flow, particularly when airway obstruction is present

Fraction of inspired oxygen 

1. Typical oxygenation goals include an arterial oxygen tension (PaO₂) > 60 mmHg & SpO₂ > 90 %

2. In ARDS, targeting a PaO₂ of 55 to 80 mmHg and a SpO₂ of 88 to 95 percent