Step 4: pH Match-up – ABG Interpretation (Nursing)

by Rhonda Lawes

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    00:00 Okay so now we're gonna look at how you figure out how the patient got there and who's fault it is.

    00:07 We introduced that a little bit in the beginning of the video, but now I wanna talk to you how you actually do it.

    00:11 It's step 4.

    00:13 We got to let the pH match up.

    00:15 We're looking for the level that matches the pH and we know that one is the problem.

    00:20 Now when we say the "level", that means we're talking about the CO2 or the bicarb.

    00:26 So remember in steps 1,2 and 3, you label the pH, step 2 - you label the CO2, step 3 - you label the bicarb Now we're gonna look at the label that you put on the CO2 and the label that you put on the bicarb and see which one is the same as the label for pH.

    00:44 If the label that you put on the bicarb matches, then the kidneys are the problem or the cause of the imbalance.

    00:52 If the CO2 matches the same label that you put on the pH, then the lungs are the problem or the cause of the imbalance.

    01:01 Okay, so look what we did for you here on the couch of homeostasis.

    01:04 You'll see that the pH of 7.35 to 7.45 is right in the middle but look at what they did with the arrows, right? so the CO2 is the darkest if you're going this direction.

    01:17 If you're greater than 45 and you're getting more acidic, notice there's a darker color On the bicarb with 22-26, I should get higher levels of bicarb, you're moving more alkalotic Soso this is a great visual image to check your understanding.

    01:36 Does that make sense to you why those arrows are lighter-colored than one end and darker on the other? So check your understanding before we keep moving on.

    01:47 Okay, you ready to have some fun? I'm excited for you to see how much you've already learned.

    01:52 I should walk through this video with us.

    01:54 So we're gonna look at a ph of 7.30, a CO2 of 55 and a bicarb of 23.

    02:02 Now let's do steps 1, 2 and 3.

    02:04 So look at the pH - step 1 is look at the pH and label it.

    02:08 You go first then I'll give you the answer.

    02:15 Alright, a pH of 7.30 is less than normal so I'm gonna label that acidic.

    02:24 Next you look at the CO2 and label it.

    02:31 Sweet! A CO2 of 55 is outside of normal, right? because I know a normal CO2 is 35 to 45.

    02:41 So 55 is definitely greater than that, I'm gonna label it as acidotic.

    02:46 So I've done stop 1, I've done step2.

    02:50 I labelled the pH and the CO2 - they're both acidosis.

    02:54 Now I'm gonna look at the bicarb.

    02:57 You go first.

    03:02 Cool, the bicarb is normal.

    03:05 so I've done steps 1,2 and 3, we've labelled the pH, the CO2 and the bicarb.

    03:14 You know what's left now is step 4.

    03:17 We're gonna do the pH matchup, see which one matches Well the pH is labelled acidosis. the CO2 is also labelled acidosis.

    03:24 The CO2 is also labelled acidosis.

    03:27 The bicarb is normal.

    03:29 So since the CO2 matches the pH's label, then we know that the cause is respiratory.

    03:36 So we're in acidosis, we know it's the lungs' fault, so we're in respiratory acidosis.

    03:43 Cool, the metabolic problem was an issue because we still had a normal range.

    03:48 Now we'll talk about what the kidney should be doing in the next step.

    03:52 But for now, let's focus on figuring out which of the big 4 you're at.

    03:57 Because in acidosis, that tells us the pH is less than 7.35 We're in a respiratory acidosis because those are the two labels that match.

    04:07 It's the lungs' fault because they control the level of CO2.

    04:12 Okay, now here steps 1 through 4 on your own.

    04:16 So pause thw video, walk through labelling the pH, looking at the CO2 and label it, looking at the bicarb and labelling it and step 4, doing the pH match up and you come up with which one of the four places you are Okay, let's see how you did.

    04:37 In step 1, the pH was 7.54 So since that's greater than 7.45, I hope you've labelled that alkalosis.

    04:46 Now CO2 is 28.

    04:48 Now that's less than normal, right? because normal CO2 is 35 to 45, so you label that alkalosis.

    04:56 The bicarb was normal - 24 , in between 22 and 26.

    05:01 Now that's steps 1, 2 and 3 at the top Step 4, you look at the pH and see if the CO2 or the bicarb matches.

    05:11 Well since the CO2 matches, then we know that the lungs are at fault so we have less CO2 than normal.

    05:19 So at what rate you think those lungs are breathing, very fast or very slow? Right, very fast because it's blowing off the CO2.

    05:28 This patient is in respiratory alkalosis.

    05:33 Good job.

    05:34 Now think about the reasons of patient could be in respiratory alkalosis.

    05:38 We know they're breathing very fast, one of the most common reasons is pain.

    05:42 They also might be anxiety, they might be afraid of something, so your job as a nurse is to figure out what's going on and to help the patient resolve that.

    05:51 Because we saw that the pH is alkalosis, the CO2 is alkalosis so we know where we are - we're in alkalosis.

    06:00 We know whose fault it is because the CO2 level that matched, so we're in respiratory alkalosis.

    06:08 Great, okay you're really catching on the how to do this, soon you'll be ready to do it all on your own.

    06:14 So we're going to try another example.

    06:16 You do steps 1 through 4 on your own, pause the video, we'll come back and talk about the answers.

    06:26 Okay, let's see how you did, compare your answers to our answers.

    06:31 pH of 7.25 is less than 7.35 so it's labelled acidotic.

    06:37 The CO2 is 37 - well that's normal because the normal CO2 levels are 35 to 45 Bicarb, woah there's our problem.

    06:47 Noarmal is 22 to26, so it's less than 22, it's at 18 so we label that acidotic.

    06:55 Step 4 - look at the pH label, it's acidotic then look at the CO2 or the bicarb, which one matches? Of course, the bicarb. So what does that mean? We're in acidosis, that's where we are because the pH is less than 7.35 and whose fault it is is the metabolic system, the kidneys - our bicarb levels are too low That's why we're in metabolic acidosis.

    About the Lecture

    The lecture Step 4: pH Match-up – ABG Interpretation (Nursing) by Rhonda Lawes is from the course Interpretation of Arterial Blood Gases (ABGs) (Nursing).

    Included Quiz Questions

    1. Respiratory acidosis
    2. Respiratory alkalosis
    3. Metabolic acidosis
    4. Metabolic alkalosis
    1. Respiratory alkalosis
    2. Respiratory acidosis
    3. Metabolic alkalosis
    4. Metabolic acidosis
    1. Metabolic alkalosis
    2. Metabolic acidosis
    3. Respiratory acidosis
    4. Respiratory alkalosis
    1. Metabolic acidosis
    2. Metabolic alkalosis
    3. Respiratory acidosis
    4. Respiratory alkalosis

    Author of lecture Step 4: pH Match-up – ABG Interpretation (Nursing)

     Rhonda Lawes

    Rhonda Lawes

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