Hey everyone, I'm going to talk about metabolic acidosis. So let's get started. Metabolic acidosis occurs whenever we have too many acids in the body and this leads our blood pH to fall along with our bicarb level, which is the HCO3 level. Now this tends to occur really due to two reasons.
The first reason being there is just too much acid production in the body. Some process in the body is messed up. And we have way too many acids hanging out there. Or secondly, there is failure of our body to actually excrete or rid itself of these acids. So what are some things that can do this?
Well, to help us remember those things, let's remember the word acid. acids. So A is for accumulation of lactate, which leads to lactic acidosis.
And this happens in cases of sepsis. C is for chronic diarrhea, where the patient is just losing too much bicarb through their stool. So bicarb is this like basic substance, it helps neutralize acids. And if we're losing a lot of the substance that helps neutralize acids, we're losing the ability to keep those acids in control, which could lead to acidosis.
I is for impaired renal function. So your kidneys play a huge role in helping you balance those acids in your body. It can help get rid of those hydrogen ions.
So if we have kidneys that aren't working very well, we're going to start to have high amounts of waste, hence acids in the body. which leads us to acidosis. And then D for DKA, which stands for diabetic ketoacidosis. So already in that name, you see acidosis. So we're dealing with something that's acidic.
And with this condition, we have an increase of ketone production, which is acidic and causes our blood pH to fall. And then lastly, we have for S salicylate. toxicity.
So these are acidic substances. So if a patient has too much of these in their system, it could cause acidosis. Now to help us understand metabolic acidosis a little bit better, let's take a moment and talk about acids. So your body metabolizes substance to function. This process is going to break down fats, carbs, and proteins, and it's going to take energy from that and give it to us.
Now, unfortunately, I... byproduct of this process is the creation of acids. So what are acids? Well, these are materials that once broken down in a solution, they create hydrogen ions.
And this is what a pH level measures, the hydrogen ion concentration. And our body needs a narrow pH range in order to function. It needs a range between 7.35 to 7.45.
Anything less than 7.35 is too acidic and anything greater than 7.45 is too alkaline. So hydrogen ions play a huge role in affecting our pH level. It actually decreases the level and makes the body acidic.
So if you have too many hydrogen ions in the body, that is going to lower our blood pH and make it less than 7.35. If you don't have a lot of hydrogen ions in the body, it's going to raise that blood pH and make it greater than 7.45, making it too alkaline. Now our body knows that this can happen.
So it has these systems in place to help balance this out. The body wants a 20 to 1 ratio of bases versus acids. So for every 20 bases you have, it wants one acid so it can keep the acid base balance.
So the body uses systems to remove and neutralize these acids. And what really neutralizes an acid? A base.
So bases neutralize acids. And the body can use the respiratory and the renal system to help remove move or conserve them. Now how do we get the creation of hydrogen ions in the body? Well it's through carbonic acid. Carbonic acid is a weak acid in the body that plays a role in acid-base balance.
It comes from carbon dioxide and it's formed when carbon dioxide binds with water in the body. So when you breathe in and you take in carbon dioxide and it enters your blood it's going to bind with that water. Whenever those two bind together, it forms carbonic acid. Now carbonic acid is weak.
It doesn't stay together too long. It actually breaks apart and creates hydrogen ions. And hydrogen ions can neutralize bases. So for a second, let's talk about bases. Bases are materials that once broken down in a solution, they neutralize acids by binding with hydrogen ions.
Hence, it acquires a hydrogen ion and neutralizes it. Bicarbonate, HCO3, is a weak base in the body that helps neutralize acids and when they do this they help increase that blood ph when it neutralizes hydrogen ions it causes carbonic acid to form which breaks apart into water and carbon dioxide and then this is exhaled through the lungs also the kidneys can excrete or conserve bicarb as needed to help balance the ph level so now let's take a deeper look into the respiratory and renal system that helps us balance these acids and bases. With the respiratory system it will control the carbon dioxide levels.
Either it will cause us to retain co2 or blow off co2. So it will control the rate of how fast we breathe and how deep we breathe. With acidosis one of the big things you're going to see with these patients because their body's trying to compensate for this is that they're going to have fast deep breathing known as small breathing and why their body is doing this is because it's trying to blow off all that carbon dioxide. Now why does your body want to blow off carbon dioxide? Well what we just discussed is whenever carbon dioxide enters the body hits the blood binds with water we get the formation of carbonic acid.
Carbonic acid is a weak acid it breaks apart and it's going to affect our hydrogen ions. Too many hydrogen ions in the body lowers that blood pH. So we can get rid of that extra carbon dioxide through breathing. We can alter carbonic acid which is going to alter hydrogen ion concentration. So in hopes we're going to increase that blood pH to normal. Now the respiratory system usually does this within minutes so it's a pretty fast acting system.
However, the renal system, I like to refer to it as the slow and steady system. Once it takes over, it does a pretty good job of helping us balance the acid and bases, but it can take up to days. So what a renal system can do is that it can mess with the bicarb levels, the HCO3.
So we've learned that HCO3, bicarb, It's basic. It neutralizes acids. So if we're hanging out in some acidotic conditions like with metabolic acidosis, we need us some bicarb.
So the kidneys they know this. So what they can try to do is they can start to retain bicarb which will help neutralize those acids. When we neutralize acids, we increase blood pH back up.
Plus the kidneys, specifically those nephrons within the kidneys, can start tweaking the hydrogen ion concentration. So we can start excreting extra hydrogen ions. Now how are a patient's arterial blood gas results going to look whenever they're in metabolic acidosis?
Because ABGs is one of the great ways we can tell if a patient is in this type of acid-base imbalance. So whenever you look at those ABGs, you're going to look at three things. You're going to look at the blood pH. Again, what was a normal?
7.35 to 7.45. So with acidosis, it's going to be less than 7.35. Next you want to look at that bicarb level, the HCO3. A normal level is 22 to 26 milliequivalents per liter.
With acidosis, because we're talking about metabolic acidosis, HCO3, that's telling us we're dealing with a metabolic disorder, it's going to be less than 22 on the acidic side. And then the PaCO2, which represents our respiratory system, a normal level of that is 35 to 45 millimeters of mercury. With acidosis, it could be normal, so it could be within that normal range. But if the respiratory system is trying to compensate, like how we just talked about a moment ago, that level will be less than 35 because it's telling us it's trying to lower.
those carbon dioxide levels. So if it was that and our blood pH was still abnormal, it would be partially compensating. Now let's work an arterial blood gas problem because for your exams, chances are you're going to have some of these on there if you're being tested on this material.
So we're going to go over this problem here. This problem comes from my workbook I released called ABG Interpretation if you would like more practice or more explanation on this topic. Our problem says that our blood pH is 7.26, our bicarb is 17, and our PaCO2 is 39. So to work this problem, I'm going to use the tic-tac-toe method.
You could use Rome, whatever you're comfortable with. So we're going to put up our grid. We're going to have acid over here, normal in the middle, and then base here on the right.
and we're looking for a vertical three in a row. If we don't have a vertical three in a row, we got full compensation going on. So first thing, blood pH, it's 7.26. Is that acidic or basic? It's acidic.
So we're gonna put pH under acid column. Then we're going to look at our bicarb at 17, 22 to 26 is normal. So it's on the acidic side, so we're gonna put our bicarb HCO3 under acid.
And then we're gonna look at the PaCO2, That is 39. So a normal is 35 to 45. So this is actually normal. So we're going to put PaCO2 under normal. So we're looking for a vertical three in a row. Do we have one? We absolutely do.
So we have acid under acid. We have pH and we have bicarb because HCO3 represents that. So it tells us we have a metabolic problem.
We have metabolic acidosis. So that's established. Now we need to determine, do we have full compensation going on? Do we have partial compensation or uncompensation? We can go ahead and rule out full compensation because our blood pH is normal.
So we don't have to think about that. Now we need to determine, do we have uncompensation or partial compensation? And the answer is uncompensation. And how do I know that? Well, the reason I know that is because that PaCO2, which is a respiratory system, it should be trying to tweak our pH by making it increase so it can become normal.
It's not doing anything. It's hanging out in normal range. So it's not compensating right now. Now, if it was partial compensation, that PaCO2 would need to be less than 35 because that tells me it's thrown itself in more alkaline numbers to hopefully help lower the CO2 so we can increase that blood pH. So we just seen what some ABG results can look like on a patient in metabolic acidosis, but how's the patient going to look whenever you're in the room assessing them? Well, number one, we established that their breathing rate is going to be abnormal.
They're going to have that small breathing where it's fast and deep. And why are they doing that? To breathe off that CO2.
Also, neurally, they're going to be confused. They can be weak. Their blood pressure can be affected.
Another big thing is you want to look at their ECG. You want to make sure that their T waves aren't abnormal because they can present with hyperkalemia. Acidosis leads to this. Now why is this?
Well, whenever a patient has severe acidosis, it causes the potassium inside the cell intercellularly to move outside the cell extracellularly, which is going to elevate those levels. Now what are some nursing interventions for the patient that you want to remember? Well, one thing you want to remember is that with metabolic acidosis, They need to find the cause and treat it.
And there's a lot of causes that can lead to metabolic acidosis when we talked about our pneumonic acid. So the treatments will vary depending on the cause. Therefore, as a nurse, one thing you really got to keep an eye on is the patient's electrolyte levels.
So one level you want to pay attention to is that potassium level, which is what we just talked about. So you're looking for hyperkalemia, but here is the thing about it. Once this acidosis starts resolving, especially in a patient who has diabetic ketoacidosis, what can happen is that you're going to have a problem with hypokalemia. So now we're going to be dealing with a low potassium level.
And why is that? Well, a lot of times with DKA, one of the interventions you're going to be doing per the doctor's orders is you're going to be administering IV fluids and insulin. So whenever we give insulin, what insulin does is that it will cause potassium to actually move inside that cell. When we move it out of the blood inside the cell, we can cause hypokalemia. So you want to monitor for that.
You also want to make sure that you're monitoring the patient's neurostatus and that you're ensuring their safety. And some IV fluids that could be given, again, this varies depending on why your patient's in metabolic acidosis, but some fluids could include sodium bicarb or normal saline. And if this is being caused by renal failure. the patient can go for dialysis, which will in a sense act as the kidneys and filter out the blood and help increase our blood pH back to normal.
Okay, so that wraps up this review on metabolic acidosis. If you'd like to watch more videos in this series, you can access the link in the description below.