Factors Affecting End-tidal Carbon Dioxide (EtCO₂) (Nursing)

00:00 Now, I wanna talk to you about -- okay. I've got this machine. I've got this patient.

00:05 Now I've got numbers that are high or low. How do I figure out what it is? Yeah, that is the fun part of nursing.

00:12 Being like a detective, putting all these clues together and figuring out what's going on with your patient.

00:18 Well, here's an overall rule. We're gonna talk about specific causes of elevated end tidal CO2 and specific causes of decreased end tidal CO2.

00:28 But I wanted to give you like some big categories to look at first.

00:31 So, increase end tidal CO2 is usually due to hypoventilation or increased metabolic activity.

00:41 So, an easy way to remember that, you know, hypo means low.

00:45 Hypoventilation, they're not able to breathe enough.

00:48 Or, increased metabolic activity means, something's going on in their body and they need a lot of extra oxygen and needs for that.

00:58 And they're just not getting that supply. So, this is not enough.

01:03 So the end tidal CO2 is going to be going up.

01:06 Now, decreased end tidal CO2, this happens in cases of hyperventilation.

01:12 Okay. That's cool. So we know one is hypoventilation, one is hyperventilation.

01:18 So make sure you have those particular words highlighted, underlined, circled, whatever your method is, but you need to have that concept kinda set in your brain, and it will help you remember all the other specific causes we're gonna talk about.

01:34 So, elevated end tidal CO2 is hypoventilation or increased metabolic activity.

01:40 Decreased end tidal CO2 is hyperventilation.

01:45 Now, it could be -- so, hyper on this one.

01:48 Also, it might have decreased cardiac output or poor pulmonary perfusion like if your patient's in shock. Okay. So, decreased end tidal CO2, either hyperventilating.

02:01 Or, we've got decreased cardiac output, the amount of blood, the heart can push out, right, per minute or poor pulmonary perfusion. Those are examples of things that happen in shock.

02:16 So, if I have a patient in shock, am I likely to see a decreased end tidal CO2 or an elevated end tidal CO2? Right. Decreased end tidal CO2.

02:30 I have a patient whose respiratory rate is really, really slow.

02:34 Am I likely to see increased or decreased? Increased.

02:39 So before you go on to the next slide, I would love you to take this slide, just jot some ideas down before we go on.

02:47 Just jot some ideas down of what you think might be examples of increased or decreased.

02:58 Okay. Now let's get specific.

03:00 Let's see how many of these you've got just thinking through what you know about the body and how it works.

03:07 So, let's look at some specific causes of elevated end tidal CO2. Now, metabolism.

03:13 Here's some reasons. Pain. If a patient's in pain, that definitely increases their metabolic needs.

03:20 Now let's look at the respiratory system.

03:23 They don't have an appropriate respiratory delivery. Right? For some reason, it's just not hitting the mark. They have respiratory depression.

03:32 They might have COPD. They might be over sedated.

03:36 There's something that's causing them to not breathe as well as they normally would.

03:41 So you're gonna have to decide what is the next step, what needs to be done.

03:45 Well obviously, if it's analgesia or oversedation, we're gonna give something -- like if it's an opioid, we're gonna give something like Narcan or naloxone to knock those opioid receptors off, get that off those mu receptors so the patient wakes up and can breathe on their own.

04:01 So, always, we want to remind you, whether it's a lab test or a machine giving us a number.

04:08 They're worthless unless there's an excellent nurse looking at those numbers, interpreting what they mean and comparing and correlating them with the patient they're taking care of.

04:20 Now what about your circulatory system? Now we're talking about your heart.

04:23 So, elevated end CO2 can be caused by an increased cardiac output.

04:30 Lastly, medications. Things like bicarbonate could cause an elevated CO2.

04:36 So, we've got four categories here.

04:41 Think through those one more time before we go over to decrease end tidal CO2.

04:47 Make sure they make sense to you.

04:55 Okay. Now let's look at the opposite end of the spectrum. We're gonna look at decreased end tidal CO2.

05:00 Now, we looked at reasons for elevated metabolism, pain, hyperthermia and shivering.

05:06 Now, we're gonna look at the opposite.

05:09 Now this one could also be metabolic acidosis. Okay? That's -- how would we determined that? Well, we would draw AVG's and we would interpret the pH, the CO2, the bicarb and that's how we would identify or diagnose metabolic acidosis.

05:25 So as far as metabolic causes go, hypothermia and metabolic acidosis.

05:32 Now the respiratory system, compared the both of them, you know what causes elevated end tidal CO2, decreased end tidal CO2.

05:40 The alveolar hyperventilation could also be a bronchospasm or mucus plugging.

05:47 So these are other signs of trouble on the respiratory system that could cause decreased end tidal CO2.

05:54 So now we're gonna have to look at, "Hey, what's going on?" If I think alveolar hyperventilation, I'm gonna worry about if they're on a ventilator.

06:02 Are the settings too high? Too intense? Gotta work with the respiratory therapist, healthcare provider.

06:07 If they're having bronchospasms, I know what those are.

06:11 That's that sudden clamping down of smooth muscle.

06:14 So I'm really gonna have to figure out, "Hey, what can we do to start relieving those?" Figure out what's the underlying cause of that bronchospasm and try to address that.

06:23 Mucus plugging is really scary. Okay? I hate it when that happens because you have to do some extreme suctioning and really work with the patient.

06:31 You wanna try and loosen up those secretions on a regular basis.

06:35 But when a patient has a mucous plug that's in the wrong spot, that's an emergency.

06:41 Because that's just like having a pulmonary embolism in your blood supply, having a mucous plug in your airway.

06:46 It's like you just swallowed a big foreign object and it's blocking the airway.

06:50 So it's a pretty intense moment to get that relieved for your patient.

06:54 Now lastly, we talked about the circulatory system.

06:58 Over on the other side, we talked about increased cardiac output for elevated end tidal CO2.

07:05 For decreased end tidal CO2, now you're gonna have hypotension.

07:10 Some reason the patient might have sudden hypovolemia.

07:13 That means sudden hypovolemia's, probably not dehydration, it's probably hemorrhage.

07:19 Some major injury is called the patient to hemorrhage.

07:23 That's why they have sudden hypo low volume. Also cardiac arrest.

07:28 So if the heart's not pumping, blood is not moving then that's why we have a problem with decreased end tidal CO2.

07:37 Lastly, pulmonary emboli. That means a blood clot likely has broken off from another part of the body, traveled through to the pulmonary vasculature, same deal.

07:48 Now you're cutting off the blood supply in that critical area, right, coming from the heart, going to the lungs, coming back to the heart to go to the body.

07:58 But boom, it's at a dead stop in the pulmonary vasculature, so it's not making it to the rest of the body.

08:05 Now, it's all about location with the pulmonary emboli depending on where it is, how major a vessel it is, how early it is as to how severe the circumstances wind up being.

08:15 Some people survive pulmonary emboli. Some people die pretty quick and we cannot bring them back in a code like situation.

08:24 So, the range is pretty wide with pulmonary emboli.

08:26 What we're focusing on here is, do you have clear in your mind.

08:30 Can you picture the red side and the green side? Look at elevated end tidal CO2 and decreased end tidal CO2.

08:37 I would really recommend you pause, and don't put this off till later.

08:42 Spend 3 to 4 minutes, really looking over this chart and make sure it's as solid as it can be at this point in your own brain.

08:51 So cover things up, see if you can remember it, do those things that start jarring your memory to remember the causes of both elevated and decreased.

08:59 Then come back and join us and we'll keep moving forward.