Just learnt from a colleague how to check if an emphysema patient is a CO2 retainer or not:
Get them to hold their arms out straight in front of them, and their palms away from them (like they are pushing a wall away or stopping traffic). If they are having rhythmic spasms, pulling their hands back a bit, it is a sign that they are retainers. If they are to weak to hold their arms out you can support them for the patient.
Apparently this is also a sign for people with a certain liver disease. Pre hospital no big deal, one patient would most likely be complaining of shortness of breath, the other of abdo pain.
Unfortunately I do not know much more, but I will have to look this up, really quite interesting (we just had a patient presenting with a positive result to this test/experiment).
