QuestionSBA
QuestionChoice
Whilst this is another important differential in any sudden onset dyspnoea, especially in a younger patient with a smoking history, the normal respiratory examination points away from this. Additionally, the elevated oxygen further suggests anxiety is a more likely cause.
10035476
e
Pneumothorax
QuestionChoice
This ABG shows a respiratory alkalosis with a high pO2. In conjunction with the age of the patient and normal respiratory examination, this suggests breathlessness caused by anxiety leading to hyperventilation.
10035472
a
Anxiety
QuestionChoice
This history does not suggest pneumonia as there is no mention of cough or fever accompanying the breathless. Pneumonia may cause a T1RF, however, the oxygen in this case is elevated (due to hyperventilation) rather than decreased.
10035475
d
Pneumonia
QuestionChoice
Whilst this patient has a smoking history, they are likely too young to have developed COPD. The ABG shows no evidence of changes you may expect with COPD including hypoxaemia or acidosis due to CO2 retention.
10035474
c
COPD
QuestionChoice
Whilst this is an important differential for any patient with sudden onset shortness of breath, this patient does not seem to have any strong risk factors for a pulmonary embolism. Additionally, they are not hypoxaemic, further pointing towards anxiety as a more likely cause.
10035473
b
Pulmonary embolism
QuestionComment
Sudden onset shortness of breath and respiratory alkalosis - albeit it can be a panic attack, but you cannot exclude PE - at least include observations
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User
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Neutrophillia
Concept
Chapter
2693
4338
Respiratory alkalosis
Topic
132
Respiratory
19498
Anxiety can manifest as sudden shortness of breath, often accompanied by respiratory alkalosis due to hyperventilation.
A 27-year-old male has sudden onset shortness of breath. He denies any other respiratory symptoms but discloses that he smokes 15 cigarettes a day and has done so for the past 10 years. The examination of his chest is unremarkable, with no audible wheeze or crackles. He has no other relevant past medical history.


His ABG on room air shows:


||||
|--------------|:-------:|------------------|
|pH|7.46|7.35 - 7.45|
|PaO₂|15 kPa|11 - 15|
|PaCO₂|4 kPa|4.6 - 6.4|
|Bicarbonate|25 mmol/L|22 - 30|
|Sodium|135 mmol/L|135 - 145|
|Potassium|4.3 mmol/L|3.5 - 5.3|
|Lactate|0.6 mmol/L|0.6 - 1.4|


What is the most likely diagnosis?
a