Case 3

A 66-year-old woman presents with left sided chest pain and shortness of breath of sudden onset.
She is a longstanding smoker who has recurrent chest infections. She has had a previous pulmonary embolism related to pregnancy.

She has:

• Pulse rate of 90
• Respiratory rate of 26
• BP = 100/70
• SaO₂ of 93% on air, rising to 95% on 15L of oxygen

Her temperature is 37.4 degrees centigrade.

Auscultation of her chest reveals a few bilateral scattered expiratory crackles but nothing focal.

What conditions would you include in her differential diagnosis at this stage? See if you can list at least four of them:

Which two of the following initial investigations would be most appropriate in refining the differential diagnosis?

The ECG shows no acute ischaemic changes and the CXR reveals no focal abnormality. What is the most important serious pathology that still needs to be excluded and what would be the most appropriate investigation to achieve this?