급성호흡곤란증후군, 임상적 진단, Acute respiratory distress syndrome(ARDS), clinical diagnosis(Berlin definition)

​대부분의 환자에서 ARDS는 배제적 임상 진단입니다. 비록 ARDS가 조직병리학적으로 진단될 수 있지만, 임상의는 전형적으로 ARDS의 원인이 되거나 흉내내는 다른 중요한 원인들을 배제하거나 확진하기 위해서만 폐 조직검사를 시행합니다.

For most patients, ARDS is a clinical diagnosis of exclusion. Although ARDS can be diagnosed histopathologically (eg, classically diffuse alveolar damage [DAD] in the early stages), clinicians typically only perform lung biopsy to confirm or exclude other important etiologies that can cause or mimic ARDS. Because it is under recognized, it is essential to have a high clinical suspicion for ARDS in those at risk.

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ARDS는 일단 ①cardiogenic pulmonary edema와 ②급성 저산소성 호흡 부전과 양측 폐 침윤을 일으키는 다른 원인들을 배제한 이후에 진단될 수 있습니다.

Clinical diagnosis (Berlin definition) — ARDS can be diagnosed once cardiogenic pulmonary edema and alternative causes of acute hypoxemic respiratory failure and bilateral infiltrates have been excluded.

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The Berlin Definition of ARDS requires that all of the following criteria be present for diagnosis:

★ Respiratory symptoms must have begun within one week of a known clinical insult, or the patient must have new or worsening symptoms during the past week.

★ Bilateral opacities must be present on a chest radiograph or computed tomographic (CT) scan. These opacities must not be fully explained by pleural effusions, lobar collapse, lung collapse, or pulmonary nodules.

★ The patient's respiratory failure must not be fully explained by cardiac failure or fluid overload. An objective assessment (eg, echocardiography) to exclude hydrostatic pulmonary edema is required if no risk factors for ARDS are present.

★ A moderate to severe impairment of oxygenation must be present, as defined by the ratio of arterial oxygen tension to fraction of inspired oxygen (PaO2/FiO2). The severity of the hypoxemia defines the severity of the ARDS:

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• Mild ARDS – The PaO2/FiO2 is >200 mmHg, but ≤300 mmHg, on ventilator settings that include positive end-expiratory pressure (PEEP) or continuous positive airway pressure (CPAP) ≥5 cm H2O.

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• Moderate ARDS – The PaO2/FiO2 is >100 mmHg, but ≤200 mmHg, on ventilator settings that include PEEP ≥5 cm H2O.

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• Severe ARDS – The PaO2/FiO2 is ≤100 mmHg on ventilator settings that include PEEP ≥5 cm H2O.

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ARDS에 대한 international consensus definition은 근본적인 병인과 관련된 기준을 지정하지 않기 때문에, ARDS diagnostic umbrella에 포함되거나 포함되지 않아야 하는 조건과 관련하여 일부 불확실성이 남아 있습니다. 일반적으로 diffuse alveolar damage을 유발하고 시간이 지남에 따라 호전될 가능성이 있는 질환이 포함됩니다. 따라서 바이러스성 폐렴 또는 diffuse bacterial pneumonia와 급성 흡입 손상이 포함되는 반면 호산구성 폐렴과 collagen vascular disease와 관련된 diffuse alveolar hemorrhage는 포함되지 않습니다.

Because the international consensus definition of ARDS specifies no criteria relating to the underlying etiology, some uncertainty remains with respect to which conditions should or should not be included under the ARDS diagnostic umbrella. Generally included are disorders that are known to cause diffuse alveolar damage and have the potential to resolve over time. Thus, viral or diffuse bacterial pneumonia and acute inhalational injuries are included, whereas eosinophilic pneumonia and diffuse alveolar hemorrhage associated with collagen vascular diseases are not.

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REF. UpToDate 2019.08.06

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