Dear Marion,

About an hour ago, Klemens stopped by, having just returned
from taking his specialty board exams in internal medicine.
He thinks he did well. He'll have to repeat the examination
in ten years. I took the occasion to present to him, without
stating my opinions and prejudices,  details about your recent
medical encounters. I recited your symptoms as tiredness and
slight shortness of breath. He's not so sceptical as am I about
the sleep apnea studies, and thinks they might be worthwhile.
He asked about the hemoglobin, which I presume has been checked
and found normal. He mentioned that some blood pressure medication
might cause tiredness. He thought the echocardiogram was a (much)
more reliable indicator of right ventricular dysfunction than
chest X-ray or EKG, and that the CT scan was (much) more sensitive
in detecting pulmonary emboli that the chest X-ray. So I stand, or
more literally, sit corrected. I've learned something. Nephrologist
that he is, he thought it was important, preliminary to CT scan,
to be certain that kidney function was normal, because otherwise
the intravenous contrast medium might cause complications. He
thought that at age 70, the radiation from a CT scan (1/5 of
that experienced five miles from Hiroshima Ground 0) was acceptable.
I asked about the desirability of ultrasound exam of the legs,
since if one suspects pulmonary embolism, the legs would be the
most likely source, and he thought at this time, ultrasound of the 
legs was reasonable, but not imperative. Without my prompting, 
he mentioned cost, and that how much you would be required to pay 
should enter into your decision.

I hope this helps.

Jochen