RE: home testing as good, and cheaper than sleep lab testing.
You are correct in one way, but not in another - there are several steps to a diagnosis of any illness, starting from suspected/preliminary to primary to confirmed. In order to provide guidelines for practitioners to arrive at list of possible illnesses for a given set of symptoms, we have a general description of various sorts of illnesses, often based on the Latin or Greek root name for the observed problem.
Apnoea means cessation in breathing (and there are tons of different apnoeas, not every one related to sleep and not every one an illness - deep free diving for instance is a type of apnoea sport) and in sleep apnoea is usually accompanied by some sort of hypopnoea. Almost any cessation in breathing, no matter how short, will cause some desaturation of the O2 levels (actually, it is a build up of CO2, but we measure it from the O2 saturation in the blood). So our preliminary diagnosis is based on the O2 desaturation levels OR on the observed cessations of breathing. From there we see via further testing if the patient meets the necessary criteria for the clinical definition. In short, a visible number of sO2sat desaturations over a given night would indicate to any examiner that the patient should be tested for a suspected sleep apnoea, providing there are no other visible circumstances to deny the preliminary diagnosis. However, it does not constitute a final diagnosis, and certainly not a clinical diagnosis and treatment method.
Your mistake in in your definition of hypopnoea. In my medical dictionary on my desk (admittedly it is the Swiss standard version, not the US) the definition is a sustained period of overly shallow breathing or an abnormally low respiratory rate. There is no included definition of O2 desaturation within it, but it is assumed that such would be the case anyway.
That is a round about way of saying that yes, I think you missed my point a bit, by sticking to your dictionary definition of the overall term for Apnoea, rather than general medical usage for sleep apnoea, wherein a cessation of breathing is assumed, simply by the prolonged cessation of breath, to raise the CO2 saturation in the blood stream and show a lowered O2sat readout on an oxymeter. Because of that assumption, the actual sO2sat levels are not considered clinically significant in meeting the definition, however, a series of desats would push any doctor to write in the referral "suspected sleep apnoea". While I know of no GP who gives out recording pulse-oxymeters to patients to do a first line test at home, on more than one occasion in the hospital I have encountered interns who, after looking at the overnights of patients with oxymeters on their fingers (or ear lobes - we have that type as well) as part of their monitoring for whatever (heart attacks, surgery, various illnesses, you name it) have flagged the number of desats and started a referral for SA testing.
My actual point was that while I thought that home testing is a good method of starting out diagnosis procedure, simply relying on your own recording pulse-ox to provide you with enough material to get a doctor to write a referral, as one poster suggested, is not a good idea - alone it is not reliable, and as a part of the definitions of clinical SA it is only a small part of the story and most of all, buying one because you think you might have SA instead of going to a lab and requesting a home test is a waste of money. On its own, these devices don't provide clinically significant information besides that you have a pattern of desaturation. We need more than that before we write you out a scrip for a CPAP machine. Once you have a CPAP, however, it is a very good way to accompany the data produced by the PAP device in order to monitor the progress of the treatment. Just don't think that because you come into my office with a PO readout and say you have SA that I will be impressed and send you home with a PAP machine. The most I would do is refer you to a sleep specialist, and your will have wasted 150 smackers for nothing. If you came to me complaining of feeling tired all the time, needing a nap at 4 in the afternoon each day even while still at work, showing a weight gain and a blood pressure rise, etc, yet showing a normal EKG, I would probably send you to the sleep lab anyway and have them do a work up on you, including testing all the other possibilities, like thyroid problems, etc.