I Had Two Glasses Of Wine, And Ended Up With

I had two glasses of wine, and ended up with severe cognitive dysfunction. It turned out my furnace was also leaking carbon monoxide, and so the pulse ox was normal, and my BAL was registering 3.0 on the tests, rather than 0.4. It turned out to be carbon monoxide poisoning. Under what circumstances should a doctor order a co pulse ox instead of a regular one, and why isn't that just the standard one they use?