Differentials

SIGNS / SYMPTOMS
INVESTIGATIONS
SIGNS / SYMPTOMS

A history of cardiac disease, acute myocardial ischemia or infarction, or a known low ejection fraction suggests cardiogenic pulmonary edema, as do an S3 and elevated neck veins on physical examination.

INVESTIGATIONS

Heart failure is suggested on chest x-ray by an enlarged cardiac silhouette, a vascular pedicle width >70 mm, central infiltrates, and Kerley B lines.

Brain natriuretic peptide levels >500 picograms/mL also suggest cardiogenic edema.

An echocardiogram and measurement of the pulmonary artery occlusion pressure (PAOP) may be needed if the history and physical and lab tests do not rule out cardiogenic pulmonary edema.

SIGNS / SYMPTOMS
INVESTIGATIONS
SIGNS / SYMPTOMS

A history of fever and cough with or without sputum production.

Patients may have pleuritic chest discomfort.

INVESTIGATIONS

Severe pneumonia with bilateral infiltrates on chest x-ray meets the radiographic criteria for ARDS.

If patients do not have severe hypoxemia with their pneumonia (PaO₂/FiO₂ ≤300 or SpO₂/FiO₂ ≤315), they do not have ARDS.

SIGNS / SYMPTOMS
INVESTIGATIONS
SIGNS / SYMPTOMS

Onset is usually subacute, over days to weeks.

Patients are previously healthy, with no related systemic illness.

Some authors have termed this disease idiopathic ARDS.[42]

INVESTIGATIONS

Meets all the clinical criteria for ARDS.

Best differentiated by history.

SIGNS / SYMPTOMS
INVESTIGATIONS
SIGNS / SYMPTOMS

Associated with bleeding from the small vessels of the airways (capillaritis) and seen in many conditions, ranging from autoimmune to mitral valve diseases.

Almost always a reversible form of respiratory failure, once the underlying cause is known.

INVESTIGATIONS

A syndrome of hypoxia with infiltrates on chest x-ray.

The hallmark is finding sequentially bloodier aliquots of fluid during serial bronchoalveolar lavage.

Serologic tests to look for autoimmune diseases may help differentiate it from ARDS.[42]

SIGNS / SYMPTOMS
INVESTIGATIONS
SIGNS / SYMPTOMS

Presents as a mild to severe pneumonia in previously healthy people.

Patients have an excellent response to intravenous corticosteroids.[49]

INVESTIGATIONS

The hallmark of this disease is increased numbers of eosinophils (upward of 50%) on bronchoalveolar lavage.

SIGNS / SYMPTOMS
INVESTIGATIONS
SIGNS / SYMPTOMS

A pneumonitis after inhalation of an organic antigen.

Patients present with infiltrates and a pneumonia-like syndrome that is clinically indistinguishable from ARDS if severe.

Differentiated from ARDS by clinical history of an inhalational allergen, usually of avian origin.

Corticosteroids may be beneficial.[42]

INVESTIGATIONS

No differentiating investigations.

SIGNS / SYMPTOMS
INVESTIGATIONS
SIGNS / SYMPTOMS

Acute pulmonary edema after removal of an upper airway obstruction, most commonly caused by laryngospasm.

Causes an acute respiratory failure often requiring mechanical ventilation with varying levels of positive end-expiratory pressure (PEEP).

The keys to differentiation are the history of upper airway obstruction, postsurgical development, and the rapid resolution of symptoms.[50]

INVESTIGATIONS

No differentiating investigations.

Use of this content is subject to our disclaimer