The CO2 level you're refering to is the total CO2, composed of the serum bicarbonate (about 95% of the total) and dissolved CO2. So this cannot be necessarily used interchangeably with the pCO2 level, a gas pressure as described above, that is determined either by blood gas or end tidal CO2 measurement.
Total CO2 is used to assess metabolic status, while pCO2 and ETCO2 are used to determine ventilatory status, which is what we're more interested in when we talk about sleep apnea.
The problems of gas exchange in sleep apnea occur only while you sleep, so even if your pCO2 is elevated during the night (and a sign of that could be morning headache) it normalizes during the day, so this wouldn't be a good measure of sleep apnea. Or rather, by the time you were having chronically elevated pCO2 levels, you'd be in a heap o' trouble (like the Pickwickian syndrome). Also as noted above, elevated Total CO2 has a variety of causes, so this is really something you should be reviewing with your physician.
Im2tired, you probably had carbon monoxide
poisoning (CO) rather than dioxide
(CO2). CO is the one from exhaust fumes, faulty furnaces, etc.