Thu11November0840AM 1

A 42-year-old man is admitted to the intensive care unit with severe breathlessness following a three day history of acute pancreatitis.

On facemask oxygen via a non-rebreathing mask at 15 litres per minute a blood gas measurement shows a PaO2 of 7.3 kPa. A chest x ray shows hazy shadowing throughout both lung fields. The patient's temperature is 37.5°C. An ECG demonstrates sinus tachycardia and the cardiac-specific troponin is normal.

What is the single most likely diagnosis?

(Please select 1 option)

Pneumonia

Basal atelectasis

Acute respiratory distress syndrome (ARDS) Correct

Cardiogenic pulmonary oedema

Aspiration pneumonitis

Explanation

The acute respiratory distress syndrome (ARDS) is defined as an acute respiratory condition meeting the following criteria:

Acute onset

Bilateral infiltrates (on chest x ray or CT scan)

PaO2:FiO2 ratio of less than 26.7 kPa

Lack of evidence of left atrial hypertension (PAWP <18 mmHg if available).

It has a high mortality and is most commonly caused by sepsis, trauma, direct lung injury and pancreatitis.

Aspiration pneumonitis often preferentially affects dependent lung segments. Global, disseminated CXR changes are less likely than with ARDS.

Although basal atelectasis may account for some hypoxaemia it would not account for global CXR changes in middle and upper lung fields.

Cardiogenic pulmonary oedema is a key differential and can be diagnostically difficult to differentiate from ARDS as pulmonary artery catheters are rarely inserted. However, in this patient there is no history of acute cardiac disease and there is a good history of a common trigger for ARDS. Therefore ARDS is more likely than cardiogenic pulmonary oedema in this case.

Answer Statistics

1

2%

2

1%

3

96%

4

1%

5

2%

Times answered: 343