Carboxyhemoglobin Lab Values

Hey everyone. Welcome to nursing.com. I’m Abby, and this lesson will cover carboxyhemoglobin, what this value indicates in the clinical picture, as well as what would cause its value to be increased or decreased. Let’s get started. 

Carboxyhemoglobin is a lab that is used to evaluate the amount of carbon monoxide in the blood. Now, does carbon monoxide belong in the blood? Let’s chat about it. When hemoglobin is exposed to carbon monoxide, carboxyhemoglobin is formed within the red blood cells. There are some ways to monitor this besides this lab value, but they aren’t very trusty. And in fact, if you try to get an SpO2 on a patient that has carbon monoxide poisoning, it actually might show them as saturated. But, what’s really happening is that that probe is actually seeing the carbon monoxide, not oxygen on the cells. Let’s take a look at some clinical indications. 

Carboxyhemoglobin is a test that should be measured when we think we have a suspected poisoning of carbon monoxide. Now, this could be either accidental, or intentional, and of course it’s going to lead to hypoxia and acidosis. Why, because the hemoglobin, the red blood cells, aren’t saturated with oxygen so therefore, the tissues don’t have oxygen being delivered to it and then, we have a different form of metabolism, the anaerobic, right? So, these patients might come in dizzy, have headaches, they could even have visual disturbances, lots of, uh, really nonspecific signs and symptoms so, hopefully we know.  This is an odorless gas. Uh, you know, it can be really hard to tell whether or not that’s the problem. So, we wanna make sure to put these patients on supplemental oxygen as quickly as possible. A normal value would be less than 2% saturation of carbon monoxide. Now, at baseline, smokers might be more at 10 to 15% because the carbon monoxide or rather from smoking, carbon monoxide tends to latch on to our red blood cells, and that’s why it’s so harmful for the body. This lab is collected in a green lab tube. When it’s increased, as you can guess, when the carboxyhemoglobin, remember, that’s the one that we’re talking about, so the carboxyhemoglobin is increased in the case of carbon monoxide poisoning and smoking. A decreased result would indicate that the intervention to treat someone that came in with this poisoning has been successful. Therefore, hopefully they’ve been put on a really good source of supplemental oxygen. The pressure of that oxygen administration and the gas exchange in the lungs is what’s going to boot the CO or carbon monoxide out and allow the oxygen onto the cells. 

Now, carboxyhemoglobin is the lab that we’re talking about and it’s used in any suspected carbon monoxide poisoning to measure the amount of carbon monoxide percentage, or saturation in the blood. A normal value would be less than 2%, but in smokers, that’s going to be higher, about 10 to 15% at baseline, even if they haven’t been exposed to carbon monoxide. A decreased value is what we’re going for and that means that our patient has been successfully treated. 

You all did such a great job on this lesson and this wraps it up on carboxyhemoglobin. Remember, we love you guys. We know you can do it, now go out and be your best self today and as always, happy nursing.

References:

• https://www.sciencedirect.com/topics/medicine-and-dentistry/carboxyhemoglobin
• https://www.ncbi.nlm.nih.gov/books/NBK557888/
• https://www.uptodate.com/contents/carbon-monoxide-poisoning#H2
• https://ltd.aruplab.com/Tests/Pub/2005757