Okay, let's get into it. We're going to be covering the basic overview in this part 1, including pathophysiology and memory tricks. And then we're going to break down some practice questions toward the end of this video, including the really tricky fully compensated vs partially compensated AVGs. So be sure to stick around.
So what are acid-base imbalances? Well, it's just the balance of acid and base of the body. Kind of like a tug-of-war. The body loves to keep these in balance. Measured in blood via the pH. So normal pH is 7.35 to 7.45.
Too low, under 7.35, we become acid. Basically, the body goes into acidosis. And too high, over 7.45, we become more base. The body goes into alkalosis. Now, that sounds pretty simple, right?
Well, here's where it gets confusing. The key players that keep us in balance is HCO3, known as bicarb. This is our base.
That helps to put the body in this alkalosis. So the memory trick, think of the double Bs. Base equals bicarb.
And CO2, our carbon dioxide, is our acid, pushing the body into an acidotic state. So too much CO2, we get a body that is in acidosis. So the memory trick we use, just think.
Carbon dioxide is carbon diacid, since too much carbon dioxide pushes us into acidosis. Lastly, hydrogen ions are a form of acid, found in the stomach acids as well as urine. So the memory trick, just think hydrogen ions is high acid.
Too much hydrogen ions equals an acidotic state. Now, simply organize this in your mind. What makes the body acidotic? Well, hydrogen ions get high acid, and carbon dioxide, just think carbon diacid.
And for base, which makes us alkalotic, just think bicarb base. Now, the main organs that control these are the lungs and the kidneys. So the lungs control carbon dioxide, that's CO2.
We breathe in oxygen and breathe out that CO2. Normal gas exchange, right? So just like you heard, the main way to get CO2 out of the body is by exhaling. So the less you breathe out, well, the less CO2 comes out. And so more CO2 is retained in the body, which makes the body more acidic.
So remember, more carbon dioxide means more carbon diacid, a very acidotic body. So naturally, decrease in respiratory rate, we have more acid from more CO2. Now, we see this in patients who are intoxicated or overdose or even a head injury. We have low respiratory rate, so CO2 is higher in the body. And with increased respiratory rate, we have less acid, that less CO2.
Like with hyperventilation from an anxiety attack. We breathe out all that CO2, so the body becomes less acidic and more alkalotic, that base. Now on the other side of things, the kidneys control two key players here, hydrogen ions and bicarb, HCO3. The kidneys regulate this acid-base imbalance by excreting more acid into the urine and retaining more base, bicarb. Kind of like a teeter-totter or a seesaw here.
So in the same way, it helps to balance out acid-base imbalances here. Let's just say the body has a base or... Alkalosis overload. Well, it helps to balance out the body by excreting more bicarb and retaining more hydrogen ions to make the body more acidic.
It does its part to help balance out the acid-base imbalance. So, naturally, too much or too little of either acid or base can throw the body out of balance. If one is out of balance, well then the others will try and adjust by increasing or decreasing.
In order to steady out this pH level and put it in normal range. Now this concept is called compensation. So just think the body is trying to find common ground with compensation. Just trying to find that balance. But we'll cover that in a moment here.
Now that we understand the basics behind acid and base, let's talk about respiratory versus metabolic acidosis or alkalosis. For metabolic, As mentioned before, acid can be found in the urine from those high hydrogen ions, and also in the stomach acids, right? So what happens if the patient vomits out all that stomach acid?
Well, what are we left with? Acid or base? Well, base. We're left in alkalosis, since we threw up all that acid out of the body and into the body. Now, what about renal failure?
We have broken kidneys, right? So can the kidneys excrete those hydrogen ions via the urine? Well, no. So acid is retained. putting the body into acidosis.
And lastly, we know that the intestines hold more base, right? So, say the client has diarrhea, and they poop out all their base from the body and into the potty. What are we left with?
Only acid. So, the body goes into acidosis. Okay, now our memory tricks are really fun here, so pay close attention.
With metabolic alkalosis, we vomit out all that acid, leaving us in a base or alkalotic state. So just think, alkalosis. It kind of sounds like you're throwing up with alkalosis. And you hold your stomach region, indicating that metabolic area with alkalosis. Now, this is also true with NG tube suctioning, that nasogastric tube.
Again, too much acid loss leaves us in a base or alkalotic state. So the key points to write down is vomiting and too much NG tube suctioning is metabolic alkalosis. And for metabolic acidosis, we have diarrhea, renal failure, and DKA, that diabetic keto acidosis.
So for diarrhea, you poop out all of your base, right? Which leaves the body in acidosis because only acid's left. So just think, if it comes out of your... acidosis, well then you'll be in metabolic acidosis.
Or just think, if base comes out of your butt, well then you're only left with acidosis. And in renal failure, you retain too much urine, right? So is urine an acid? Well yes, high hydrogen ions means high acid. So the memory trick we use, if your kidneys fail, then acid prevails.
And lastly, DKA, diabetic ketoacidosis. Even the name includes the word acidosis. So that one's an easy one here.
But a little side note for the pathophysiology here. These clients try to compensate with those Kussmaul respirations, that rapid breathing and hyperventilation. This is done to breathe out that acid via that CO2 to try to get into alkalosis.
So once again, the memory tricks, metabolic alkalosis, just think about vomiting and alkalosis, and metabolic acidosis is diarrhea because you poop out from your acidosis, and renal failure. Since the kidneys fail, acid prevails. Now on the other side of things, you know that you breathe oxygen in, and CO2, that carbon dioxide, out.
which we call carbon dioxide, since it makes the blood more acidic, right? So in respiratory acidosis, we have low and slow respiratory rate. So just think, the respiratory rate is slow in acidosis. Naturally, a client with hypoventilation is not breathing out that CO2.
So more carbon dioxide is retained in the body from low and slow breathing. So the memory trick... Just think of someone sleeping here or snoring like zzzz.
They kind of sound like respiratory acidosis. Sounding like someone snoring, right? So breathe slow in acidosis.
So common causes are from sleep apnea, that airway obstruction at night, which can lead to acidosis. And head trauma from being like knocked out like in a boxing match. You went to sleep, you went memes, and now you have low and slow respiratory rate and you're in az-dosis. Or post-operative, like after surgeries, when you're waking up from anesthesia and that body has been put to sleep from all that anesthesia.
The respiratory rate will be low and slow, putting us into az-dosis. Now for drugs, CNS depressants, this one's huge on exams, so write these down. This makes the breathing low and slow. It makes the vital signs in general low and slow. So opiate overdose, morphine, hydromorphone, etc.
As well as alcohol intoxication, that one's a huge one. And benzodiazepines, ending in pam and lam, like diazepam. All CNS depressants make the breathing slow, putting the body in acidosis. Now, we can also have impaired gas exchange, from let's say pneumonia, where we get thick mucus buildup inside the lungs.
So you have to ask yourself, do you have good gas exchange? Well, no. So CO2 is retained in the body, making the blood more acidic. And COPD or asthma attacks.
Do we have good gas exchange? Well, no. So, CO2 is retained. So, just think COPD retains more CO2.
Now, on the other side, for respiratory alkalosis, we have a fast respiratory rate. Hyperventilation is the key term you have to know. So, hyperventilating from, let's say, an anxiety attack from taking a nursing exam. So, the memory trick we use... Think of a person panting like a dog, basically breathing too fast.
It'll put them in respiratory hulkylosis. So the big one to know for exams is a panic attack or hyperventilation. So you have to ask yourself why though?
Well again, in hyperventilation we blow off all that carbon dioxide, that carbon diacid. So all that acid leaves the body, right? Which leaves the body in which state?
Acid or base? Well, you just blew off all your acid, so you're only left in base, an alkalotic state. So just remember, hul-hul-hul, hulkalosis. Now Kaplan mentions, what is the cause for respiratory alkalosis?
And the answer is hyperventilation. So again, just think for your exams. Every condition that's breathing too slow is acidosis. Four. respiratory acidosis.
And every condition that's breathing too fast puts the body into alkalosis. Now for the top missed exam question here. The nurse expects which client to be in respiratory acidosis.
So before looking at the options, just think here. Acidosis is that slow breathing. So option number one, morphine overdose. Yes.
It makes things low and slow, putting us into acidosis. Like snoring. Acidosis. Now, option two is incorrect. A panic attack.
We have fast, rapid breathing. More h-h-h-alkalosis. Not acidosis.
Now, option three is correct. Sleep apnea. Yes.
We have slow acidosis. Remember, like snoring. Acidosis. And option four, this one's tricky here.
COPD is correct because do we have slow or fast breathing? Hmm. So just think about it here. We actually have decreased gas exchange from chronic obstruction.
So CO2 is actually retained, putting us into acidosis. So that's correct. And option five and six are also correct. So an asthma attack, you have to ask yourself, can they breathe?
Well, no. Is that good gas exchange? Well, then no.
So we have low and slow airflow putting us into acidosis. And six was a little bit of an easy one here. Alcohol intoxication. Yes.
Alcohol is a depressant making the respiratory rate low and slow, putting us into hypoventilation with acidosis. Remember, always sleepiness is like snoring for as... So once again, a quick recap for the memory tricks here. Write these ones down.
Metabolic alkalosis is like you're vomiting up alkalosis. Metabolic acidosis means you're pooping out your acidosis for diarrhea. And renal failure, when kidneys fail, acid prevails. And for respiratory acidosis, just think about that slow breathing, that acidosis.
And for respiratory alkalosis, it's that fast breathing, that hyperventilation, kind of like panting like a dog. H-h-h-alkalosis. Okay, now that we have the basics down, here's a critical thinking exercise. What will the body do to get back into normal range?
Remember, this is called compensation. So again, think compensation is finding that common ground of balance for that pH to be in normal range. Kind of like that tug-of-war or that balancing act. The lungs and the kidneys will compensate for each other to help keep that pH in normal range.
So, too much acid, the body will breathe faster to get Alkalosis, increasing that respiratory rate to blow off that CO2, that carbon diacid, in order to be more alkalinic. We see this a lot, as mentioned before, with DKA, diabetic ketoacidosis, when patients breathe those Kussmaul respirations. And on the opposite side, with too much base, that alkalosis, the body needs to breathe more slowly to retain more of that CO2. to make the body more acidic right so we'll have patients breathe into paper bag breathing slowly and re-breathing that co2 for more carbon dioxide so a common anclax question gives you abg numbers for a client in metabolic acidosis asking how does the nurse expect the client to show compensation and a little side note don't worry about interpreting all these crazy numbers we'll break this down next So just think, metabolic acidosis, right? They need to go into alkalosis.
So, alkalosis, they need to breathe faster, hyperventilation. So the correct answer is to increase the respiratory rate to blow off all that acid, that carbon diacid. Decreasing the respiratory rate would lead to more acidosis.
So option two is correct. Lastly, before we take our ABG practice questions, here are some key points for the ABG itself. So Kaplan mentions, what is the most important objective data when determining if a client is hypoxic?
And the correct answer was abnormal blood gases. Yes, this is the most accurate way to determine oxygenation of the body. And a common exam question asks, the best diagnostic test to evaluate a patient's oxygenation Key term there. And ventilation after a traumatic brain injury.
Correct answer, arterial blood gases. I would write that one down because these came up a lot. Now, ABGs are typically done by a respiratory therapist.
Now, before the procedure, the RT will prepare to draw blood from the radial artery and do an Allen's test. This is done to determine the patency of the ulnar artery. Now, the test is done in three steps. Step 1, the client makes a fist and the RT occludes the radial artery and ulnar artery. Step 2, the palm is opened to reveal a pale palm from the lack of blood flow.
And lastly, step 3, releasing the pressure on the ulnar artery here first, the palm should regain its color in about 15 seconds or less. This indicates the key term, patency, of the ulnar artery. Now after the procedure, key terms here, you have to hold firm pressure on the puncture site.
Since we just punctured an artery and not a vein here, so there's more pressure in arteries and a higher bleed risk. So Kaplan mentions essential actions after ABGs are drawn. We have to apply pressure to the puncture site.
And Hesse also mentions the priority intervention following an ABG procedure. Hold firm pressure at... the site.
Okay, now part two of this video showing you how to solve those darn ABGs. Now, a lot of students and instructors use the ROAM or tic-tac-toe method, but that can get really confusing, especially when we get into partial versus full compensation. So, I personally created the marching band suit method for myself during nursing school and have never got a question wrong in over eight years now. So I recommend using this chart and writing it out 5 to 10 times every single day the week of your exam. So pause your screen and write this down.
Then we'll break it down and I'll explain why it's so perfect. Okay, now this chart is so great because it's so organized. Starting with the names here first on the left side. pH is on top. So just think pH is primary because it comes first.
CO2. So 2 is second. So you see the 2 there.
So that's how you know it comes second. And HCO3. Well, just look at the 3 there. That's how you know it's the third one down. Next, you just draw normal anatomy.
Lungs over kidneys. So lungs are on top, near the CO2, and the kidneys are on bottom. Okay, now for the key numbers, and you have to memorize this.
So writing it out makes it simpler. We have pH at 7.35 to 7.45. Then just drop the 7s because they went to heaven. So CO2 is just 3.5 to 4.5.
And lastly, bicarb is 22 to 26. Finally, we label it all. ABBA on the left side and BAB on the other side. So the A's are for acid and the B's are for base. So once again, pause this screen.
And again, I recommend writing this out 5 to 10 times the week of your exam. This is vital to know since this chart will save your booty on exams and even the NCLEX. Okay. Now after this chart is set up, then we can use the three steps to interpret any ABG for acid-base imbalances.
So step number one, the pH. This is our key here. Always look at pH first. Remember, pH is primary.
We must look here first. Less than 7.35 is A for acid. And over 7.45 is B for base or alkalotic.
So for example... pH of 7.2 is acidosis. And pH of 7.65, what do we have here?
Yes, it's base, alkalosis. Now, step two, we match the pH with the partner below. Let's say the pH is an acid, and the CO2, our respiratory, is acid as well. And the HCO3, our metabolic, is in normal range. Well, the two acids with pH and CO2...
Make it respiratory acidosis. Since the two acids match, and our little lung icon here tells us it's a respiratory problem. Now, if we have pH, that is base, or alkalosis, and a CO2, that's a normal range, and the HCO3 is high, very alkalotic, well then we have metabolic alkalosis.
Since the two bases match, and it's a metabolic problem here. Now, step three is the hard part here, so pay attention. Compensated versus uncompensated. Always look at the pH first. So remember, pH is primary.
The body hates to be out of balance, right? So it will try and balance the pH, acid and base, sort of like a tug-of-war or like a negotiation process to help bring that pH back into normal range. This balance again is called compensation. So once again, think compensation is finding common ground.
Just finding that balance for pH to be in that normal range. So fully compensated means that the pH is in normal range. Yahoo! This is our goal. Boom! We Gucci, baby.
And we see the kidneys here and the lungs are doing their job to work together and work out their problems. They're basically offsetting each other in order to sort of balance out the boat here and find that common ground of compensation for the pH. It's like the pH is our little baby here, keeping the pH baby happy and in normal range as the parents underneath are working through their problems with couples counseling. Now, uncompensated, this is our broken home.
Our pH baby is not in normal range. We do not have a happy baby. Oh no!
Our pH has no compensation since it's not normal. There's no common ground. And the body isn't doing anything to help the balancing act either.
It's like a lazy partner who ain't doing nothing around the house and ain't doing anything to help out the relationship. So the memory trick is think uncompensated is very unfriendly. And let me explain why. For example, let's say the pH and the lungs are in acid overload. They need some serious help.
So we expect the kidneys to help a brother out and go to base to balance us out, right? But nah, in unfriendly uncompensation, the kidneys don't care about the acid problem. They just live in their best life saying, mm-mm, not my lung, not my problem.
Mm-mm-mm. This is like some Jerry Springer type stuff. So this is uncompensated, since it's the most unfriendly. And lastly, partially compensated.
Our pH is not in normal range, but it's okay. At least the body is working through it and trying to balance itself out. It's like the lungs and the kidneys are going to couples counseling here to work things out and make steps for improvement. Sure, the body is still in acidosis, but at least base is trying here.
And that's why it's partially done. So partial compensation, it's a work in progress. All right, now for our ABG practice questions.
So using our three steps, let's break this down. ABG practice question number one here. We have a pH of 7.25, a PaCO2 of 55, and an HCO3 of 25. So using our marching band suit, let's break this down.
Step number one, starting with pH because it's primary. 7.25 is way below 7.35. So is it acidosis or in base, that alkalosis?
While using our chart, we know the A is for acidosis. acid, so acidosis. Step two, we have to find the match on the bottom. Does CO2 or HCO3 have that acid match? Well, CO2 is 55, which is over that 45, so that's the acid.
We got an acid match in the lung area because our little lung picture hints that it's respiratory acidosis. Now, HCO3 is 25, so that's a normal range. Now, step three.
three is it compensated or uncompensated so you have to ask yourself look at the ph is it normal well no so it's not in balance it did not find common ground of compensation so it would be uncompensated since it's very unfriendly here so the correct answer is respiratory acidosis that is uncompensated now for our next question abg practice question number two you We have a pH of 7.57, a PaCO2 of 25, and HCO3 of 22. So filling out your marching band suit here, then we use our three steps. So step number one, starting with pH because it's primary. So 7.57, is that acid or is it base? Well, it's way over 7.45. So that little B tells us it's base or an alkalosis.
Now, step two, we have to find that alkalosis match. So CO2 is 25. That's pretty low. So that is base as well in alkalosis. And the respiratory icon, we have a match for respiratory alkalosis.
It looks like. And HCO3 is 22. So it's technically right on the border, but it's normal. So it's not a match. Now, step three, is it compensated or uncompensated? So you have to ask, is the pH in normal range?
Well, no. So it's not in balance. It didn't find that common ground of compensation. So it would be uncompensated.
So the answer is respiratory alkalosis that is uncompensated. Okay, the next question, ABG practice question number three. the pH is 7.21, PaCO2 is 39, and HCO3 is 19. So we fill out our marching band suit. And step one, looking at the pH because it's primary. 7.21 is way below 7.35.
So we know it's the A of acid. Then in step two, we're going to find our acid match here. So CO2 is 39. That's in normal range.
So there's no match. And HCO3 is 19 on that A side. So we have our acid match. So the kidney icon tells us it's metabolic acidosis.
Now step three, is it compensated or uncompensated? So look at the pH. Is it normal? So it's not a normal range, so it's not in balance. It didn't find that common ground, so it's not compensated. So it's uncompensated.
The answer here is metabolic acidosis that is uncompensated. Now, last but not least, the trickiest questions. Fully or partially compensated? So remember, the body will try and balance the pH, the acid and base, sort of like tug of war.
This balance, once again, is called compensation. So again, think compensation as finding that common ground of balance. Again, a little recap here. If the pH is normal, between 7.35 and 7.45, this is full compensation.
And if the pH is not normal, we have partial compensation. Basically, that work in progress. So for example, say the pH is acidic, then bicarb, that base, will try to increase to balance it out.
If pH is still acidic, but bicarb is high, then it's partially compensated. So let's do an example question to see this in action. ABG question one, full or is it partial compensation? So looking at our numbers here, pH is 7.32. We have a CO2 at 55 and HCO3 at 42. So we fill out our marching band suit like normal.
Step number one, the pH is acid, 7.32. Step two, we're going to find the match like normal. And we find that CO2 is a little bit high and in the acid range.
So we know the respiratory icon, it's respiratory acidosis. So the body is in a... acidotic state. Now step three, the tricky part, compensation.
HCO3, our bicarb, is 42. So we have a high base. The body is trying to pull us out of that acidosis and back into balance. This means compensation. It's trying to work out its problems.
So it's trying to find that common ground of compensation. But here's the key point. Is it partial or full compensation.
Well, look at the pH here. Is it normal? Well, no.
So it's not fully compensated. So it's just partially compensated since the pH has not fully recovered and the body is still trying to balance itself out. So the correct answer here is respiratory acidosis that is partially compensated.
Now, ABG question number two, pH that is 7.55. CO2 of 49 and a HCO3 of 35. We're filling out the marching band suit. So step number one, what is our pH that is primary?
7.55. So that's B, that is base, alkalosis. Step number two, we're gonna find our base match here. So CO2 is in the acid area of 49, but it doesn't match to our pH base. Now- bicarb is 35 that's definitely a base match so two bases make a match and the kidneys tell us it's metabolic and the base alkalosis metabolic alkalosis now for step three the compensation of the inspiration of the perspiration okay okay compensation since co2 that acid is out of range we know that the body is trying to pull us back into balance So this means compensation.
But again, is it partial or full compensation? So look at the pH. Remember, that's primary. So is it normal?
So no, it's not normal. So it's not fully compensated since it's not fully normal. So we must conclude that it's partially compensated since the pH hasn't fully recovered yet. So the correct answer is metabolic alkalosis that is partially compensated.
Next question, please. ABG, question number three. Our pH is 7.37.
Ooh, that's normal. CO2 is 52, and HCO3 is 32. Okay, step number one, pH, that is normal. But here's the trick. It kind of looks like it's leaning toward the acid side. Now, step number two, we're gonna need to find a match.
But now you're thinking, wait a minute. How do you find a match from a normal pH? Hmm, uh-oh. Well, CO2 is in the acid area, right?
And we know that bicarb is in the base area. So, oh snap, what do we do now? Okay, okay, okay, calm down, calm down, get it together.
We're gonna pass this NCLEX, we're gonna pass our exams, we're gonna be a badass nurse. Oh gosh, I should have been an Instagram influencer. Okay, okay, ignore that inner dialogue. Remember, this acid-base imbalance is kind of like a tug-of-war, right?
So, simply ask yourself, who's winning this tug-of-war? So, look at that pH scoreboard here. Is the pH closer to the base or closer to the acid side?
Well, in this case, pH is leaning closer to that acid side, right? So, we must say that acid is winning. So, our match is CO2, that acid, since it's in the acid area.
So the answer must be respiratory acidosis. Now, step three, is the compensation fully or is it partial? Well, is the pH normal? Well, yes, it's in normal range. We have a happy baby.
So the answer is respiratory acidosis that is fully compensated. Woohoo! All right, our last and final ABG question, number four.
The pH is 7.45 and the CO2 is 43 and the HCO3 is 33. Okay, step number one, the pH is in normal range, but... it's closer to the base side so base is winning our tug of war here now step two finding our base match co2 is in the acid range so that can't be our match hco3 our bicarb is 33 that's definitely in the base side so metabolic specifically metabolic alkalosis since the bases are a match now step three compensation is it fully compensated or partially? Well, look at the pH here.
Our pH is fully normal, so it's fully compensated. So our answer is metabolic alkalosis that is fully compensated. Now that was a big video. Thank you guys so much for watching. Please be sure to download your cheat sheet study guides as well as take the quiz on the membership site.
And please be sure to share with your classmates and instructors. Thanks so much for watching.