You have just admitted a patient into ER with a decreased le…

You have just admitted a patient into ER with a decreased level of consciousness and increased work of breathing. His furnace had gone out in his house and he’d tried to heat the house by using an outdoor propane heater.  His vital signs are: RR32, HR 122, BP 135/84, SpO2 99% on room air. Despite the high SpO2 your preceptor suspects he might be suffering from anoxia and the SpO2 is inaccurate. This would be because: