Which statement about carbon monoxide poisoning is true?

Which statement about carbon monoxide poisoning is true?

• A. Pulse oximetry overestimates oxygen saturation due to carbon monoxide binding
• B. Carboxyhemoglobin should be measured on ABG or VBG to assess exposure
• C. ABG pH is unaffected by CO poisoning
• D. Hyperbaric therapy is always indicated

Answer: (B)

Measuring carboxyhemoglobin levels with co-oximetry on an arterial or venous blood gas is the direct way to assess carbon monoxide exposure. CO binds hemoglobin very strongly to form carboxyhemoglobin, which lowers the blood’s oxygen-carrying capacity and impairs tissue oxygen delivery. To gauge how much CO is affecting someone, you need a co-oximeter that can quantify carboxyhemoglobin; this is done on ABG or VBG samples. Pulse oximetry isn’t reliable here because it can’t distinguish carboxyhemoglobin from oxyhemoglobin, often giving a falsely reassuring or normal-looking saturation despite significant CO burden. The ABG pH may be affected as tissue hypoxia leads to lactic acidosis, so saying the pH is unaffected isn’t correct. Hyperbaric therapy is not universally indicated; its use depends on factors like the level of carboxyhemoglobin, symptoms, and patient status (e.g., pregnancy or neurologic or cardiac findings), rather than being automatic for every case. So, directly measuring carboxyhemoglobin on ABG or VBG best reflects exposure and guides assessment and management.

Measuring carboxyhemoglobin levels with co-oximetry on an arterial or venous blood gas is the direct way to assess carbon monoxide exposure. CO binds hemoglobin very strongly to form carboxyhemoglobin, which lowers the blood’s oxygen-carrying capacity and impairs tissue oxygen delivery. To gauge how much CO is affecting someone, you need a co-oximeter that can quantify carboxyhemoglobin; this is done on ABG or VBG samples.

Pulse oximetry isn’t reliable here because it can’t distinguish carboxyhemoglobin from oxyhemoglobin, often giving a falsely reassuring or normal-looking saturation despite significant CO burden. The ABG pH may be affected as tissue hypoxia leads to lactic acidosis, so saying the pH is unaffected isn’t correct. Hyperbaric therapy is not universally indicated; its use depends on factors like the level of carboxyhemoglobin, symptoms, and patient status (e.g., pregnancy or neurologic or cardiac findings), rather than being automatic for every case.

So, directly measuring carboxyhemoglobin on ABG or VBG best reflects exposure and guides assessment and management.