Lung ultrasound for diagnosis and management of ARDS (ICM)

這一篇ICM的文章寫很精要,值得花些時間看一些,看圖就了解文章的重點了,
以下為文章的重點整理。

利用超音波來評估ARDS,要先具備lung ultrasound掃描的基本技巧和認識。評估的區域要包含後背處,所以在重症患者掃描時,需要有人幫忙翻側以,以便進行後背部的掃描,但相較於將患者由加護單位送去CT檢查而言,這還是方便太多了。

探頭一般以弧形的腹部探頭為主要選擇,在評估肋膜表面時可以更換為線形探頭,更容易來看肋膜表面是否不規則(pleural irregularity)或是有實質病變(subpleural consolidation)。廣泛呈現B lines的形態時,可能是acute lung edema,也可以是ARDS,肋膜的評估在區分這兩者有很大的幫助,不規則的肋膜表面和subpleural consolidation的變化常見於ARDS。

掃描技巧一樣縱向掃描確認Bat sign,在有異常的肋膜區域再轉為平行肋間掃描來更完整觀察該處肋膜的病變。完整的掃描有十二個區域: 兩側前、側、後的胸部,各別再平分為上下部。配合不同lung ultrasound病變的計分,lung ultrasound score的計分介於0 ~ 36。

住院時掃描的計分基準和後續計分的變化可以用來評估往好的方向走或是變更嚴重,也可以評估是否併發了hospital acquired pneumonia。 LUS也可以用來協助評估ARDS是那種形態,Non-focal subphenotype為廣泛的病變,治療以recuritment maneuver為主; focal subphenotype主要為後背側肺部病變,這類型的患者可能會需要採用prone positioning。採用recruitment maneuver或是prone positioning後,肺部的狀況是否有改善也可以藉由LUS來評估。呼吸器使用時可能造成的氣胸用LUS來評估也比傳統的X光來得準確。持續進步和改善的LUS score也可以用來做為拔管時的重要依據,拔管時LUS score的分數如更變得更差,也可以提醒臨床人員可能還需要矯正潛在的問題後再拔管。

因應不同的狀況和醫療資源,最新的ARDS定義中,將Lung US納入影像評估的項目之一。

Subpleural consolidations: LUS image scanned with a linear probe, showing small subpleural consolidations and B-lines
Score 0: A LUS image obtained with a linear probe showing an A-line. As there are less than 3 B-lines present, it is scored as 0
Score 1: A LUS image obtained with a linear probe showing B-lines. The B-lines cover less than 50% of the pleura and therefore the image is scored as a 1
Score 2: A LUS image obtained with a linear probe showing B-lines. The B-lines cover more than 50% of the pleura and therefore the image is scored as a 2. The pleura is considered abnormal 
Score 3: A LUS image scanned with a phased array probe. The lung is consolidated and therefore the image is scored as a 3 

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