An elderly couple is taken by ambulance to the emergency department after
their son noticed that they were both acting “strangely.” The couple had been
in good health prior to the weekend. Their son usually visits or calls them
daily, but because of a terrible blizzard was not able to make it to their house.
They had been snowed in at their house until the snowplows cleared the roads.
They had plenty of food and were kept warm by a furnace and blankets. When
the son was able to see them for the first time in 2 days, he noticed that they
both were complaining of bad headaches, confusion, fatigue, and some nausea.
On arrival to the emergency department, both patients were afebrile with normal
vital signs and O2 saturation of 99 percent on 2 L of O2 by nasal cannula. Their
lips appeared to be very red. Both patients were slightly confused but other-
wise oriented. The physical examinations were within normal limits.
Carboxyhemoglobin levels were drawn and were elevated.
What is the most likely cause of these patients’ symptoms?
What is the biochemical rationale for 100 percent O2 being the
treatment of choice?