Acid base basics

Today, we're just going to have a rather quick and dirty lecture on acid base balance. Just the basics. So acid base really is not a integral part of the curriculum for this course anymore. But so many aspects of it are so intertwined with content that we do discuss that I felt it prudent to go ahead and just give some basics and try and help make some of these pieces fit together.

So acid base balance says right here the maintenance of arterial blood pH between 7.35 and 7.45 through regulation of hydrogen ion production and elimination. Oof, that definition came from, uh, very, very famous author. When in the world of nursing. Um, Donna exact. Vicky, as most of us fondly just call her Iggy because not a whole lot of people can pronounce her last name, but it kind of says what it needs to say. So let's take it and kind of break it back down. Okay, so when we discussed fluid balance in the body, we talked about homeostasis and how the body always tries to get back home basically to the place where it feels the best and where it's the most comfortable. Well, the body does the same exact thing with acid and base balance, just like it did with fluid balance. So the body's constantly in a state of flux, trying to keep our pH level between 7.35 and 7 point 4 or 5. So the body normally maintains a steady balance between the acids. And these acids are continually being produced during metabolism and the bases that either neutralize the acid or promote their excretion. So just like this slide says, it's the maintenance of arterial blood between 7.35 and 7.45. The balance depends on the regulation of these free hydrogen ions. And this balance is critical for the body to state its optimal functioning. Um status.

So to make this make more sense, what is p h? So p h is basically it's the measurement of the hydrogen ion concentration in the blood. So p is how much either hydrogen we have in the blood. So that again that normal range for arterial blood is 7.35 to 7.45. The thing that's kind of confusing about P is what they call a negative logarithm. So the lower the pH the higher the hydrogen concentration is. So a pH below 7.35 is considered acidosis because we have a higher hydrogen concentration in our blood. And then inversely the higher the pH the lower the hydrogen concentration is. So a pH above 7.5 is considered alkalosis. This seems to be really difficult to grasp. And sometimes I even have to stop and just kind of get in a quiet place in my mind and say, no, wait a minute. So there is low, so that means I have too much hydrogen. So then I can start figuring out what is going on that's making my patient have too much hydrogen or just the reverse. You know my is too high. So I have I don't have enough circulating hydrogen. I have too much buffering going on. What is going on with my patient?

So hopefully we can kind of move along on this a little bit. So when we talk about acids and bases, it's just really important to know that an acid is a substance that releases these hydrogen ions, which is going to increase the amount of free hydrogen in the bloodstream. So hydrogen is an acid. Carbon dioxide is an acid. So as part of our respiratory cycle, every time we exhale we exhale carbon dioxide. So when we talked about, you know, if your patience is low and you're having to try and figure out what's going on, what are the things you always need to look at? Is there respiratory pattern. So blowing off the carbon dioxide which is an asset if you're a patient is blowing it off too quickly. They're blowing off too much carbon dioxide. So they're blowing off too much acid so they can go into a state of alkalosis. Um, so if your patient's hyperventilating, if they're scared, things like that. Um, and then inversely, if your patient's pH is low, one of the reasons might be because the patient is not breathing effectively. So if they have too much pain medicine, if they've overdosed, if they have a head injury that's affecting their respiratory cycle. Anything that is slowing down this respiratory pattern is retaining this carbon dioxide. And then on the base. So the base is the other side of the issue. So a base is a substance that binds these hydrogen ions which is going to lower the amount of free hydrogen. So bicarb is your base. So bicarb when we talk about the kidneys we're going to be talking about bicarb. And kidneys are a big content topic in this course.

So when we talk about the body trying to maintain like a homeostatic state with their pH levels, we basically have three mechanisms that the body can use whenever the pH is out of line. So if we're not within that magical range of 7.35 to 7 point 4 or 5. So one of these first regulatory mechanisms that we have to talk about are called the chemical buffers. The chemical buffers are the first line of defense. They are always present and they act fast okay. So think of a buffer. Um, kind of like a sponge. So that sponge can soak up hydrogen when too many are present. Or it can squeeze out hydrogen when not enough are present. Bicarb again is the main buffer, but there's a couple of other ones. Phosphate can be a buffer and albumin. Here we go again albumin. So we're talking about albumin again. So these chemical buffers they they're always there. They're always ready. They're you know like the sixth player on a basketball team. They're always ready to be put in to help out okay. But the thing is is they can't last for very long. So they get in quick. They get done what they're supposed to, and then they're done. The second, um, regulatory mechanism is going to be the respiratory action. And I kind of alluded to that a little bit ago. So when the buffers alone cannot compensate, then the respiratory drive, the respiratory status kicks in to help regulate this. So again carbon dioxide is exhaled by the lungs during breathing. So if breathing is going to control the amount of free I free hydrogen by controlling the amount of carbon dioxide. So again as the carbon dioxide levels increase. The respiratory rate and depth increases to blow off this carbon dioxide. Okay. Conversely, if the carbon dioxide level is low, not enough acid, then the respiratory rate in depth is going to decrease to retain that carbon dioxide. So think about your patients. Maybe you have somebody in DKA and they're doing those small respirations. So they're doing that really really rapid breathing. They're trying to blow off their carbon dioxide okay. Because they want to decrease the amount of acid to increase their level. Um, and again, some of the most common causes that we're going to see where, um, the patient is and. Excuse me.

Sorry about that awkward pause. I'm getting a tickle in my throat, and I didn't want to cough right into the middle of this lecture. So what I was saying is that if the carbon dioxide level is low, then the respiratory rate and depth, it's going to decrease because we're going to try and hold on to some of that. You know, this gets confusing. Make sure you're reading your chapter in your book. And like I said, find someplace quiet and let your mind be quiet for a minute and let this sink in. And then the last, um, regulatory mechanism we're going to talk about is the renal regulation. And again, kidneys are going to be a huge part of our content in this course. So um, I just had to talk about them. So the kidneys are going to be the third line of defense okay. They are the most powerful defense. But the thing with the kidneys is sometimes it can take up to 48 hours for them to fully respond. That's why we need the chemical guys out there really quickly trying to get things taken care of. And then our respiratory team is just sitting there waiting to help out, and they are going to try between the two of them and hold things over until the kidneys can get involved and really change the game. So the kidneys are going to control the bicarbonate level. All right. So the bicarbonate level again is a base. So they can either increase bicarb excretion or they can decrease bicarb excretion whatever they need to do to help compensate. And they also control the hydrogen which is the acid. So they can either reabsorb the hydrogen to decrease the pH making it more acidic, or they can excrete the hydrogen and do the urine to increase the pH, making it into a more alkaline state. So when these regulatory mechanisms fail, is when your patient is going to be left with an acid base imbalance. So again below 7.35 is going to be acidosis. Above 7.4 or 5 is going to be alkalosis.

So just some key points to think about guys. Acidosis and alkalosis in and of themselves. They are not a disease okay. Whether it be respiratory, whether it be metabolic it doesn't matter. The state of acidosis is not a disease. A state of alkalosis is not a disease. They are a symptom of an underlying disease process or illness going on. Okay. So remember if you have patients that are acidic or alkaline, you have to take a step back and look and try and figure out what is going on with your patient. Um, but how this is going to tie in now with our, um, electrolytes lecture is acidosis can be accompanied by high bur Kaitlyn. Mia.

So if you remember from our electrolyte talk. Potassium is a positively charged.

Iron, okay. Hydrogen is also positively charged. So when the body has too much hydrogen in your bloodstream. It will try to trade out a potassium, so it'll take a potassium from the cell and put a hydrogen in the cell to try and reduce the circulating hydrogen. Kind of like I'm going to date myself here, but the kids games, um, when you know, you have two teens and you stand and each team stands in a line and holds hands, and you play red rover. So red rover, red rover, send potassium right over. So they send a potassium over. And then the other team, you know, will get a hydrogen in return. So because they're always flexing these back and forth, if your patient has too much hydrogen the body tries to compensate by trading out a hydrogen for potassium. This can result in too much potassium circulating in your bloodstream or hyperkalemia on the inverse side, if you are alkali stick, then they're going to be swapping it back the other way. So they're going to be sending potassium to the cell and taking the hydrogen back out. So you can end up with too low of a level of potassium in your bloodstream. So I know. Gosh, I wish I could make this an easier lecture. I'm really not for sure how though. Um, just go ahead and make sure that you're reading it in the book. Think about the key points that we talked about. Okay. Um, the way the body tries to compensate the kidneys. Pardon it, the respiratory drive in it, um, that it's not a disease in and of itself. It is a symptom of something else deeper and more insidious happening someplace. You're going to have electrolyte shifts, you're going to have some fluid shifts and things like that. As of right now in this course, I will not be asking you to interpret, um, ABG results. So the blood gas results or anything like that. I just wanted to give you some of the high points and some of the key points to think about, because it really does fit in with our content. And I don't know how you can talk about kidneys without understanding this. And I don't know how you can talk about, um, electrolytes without understanding the relationship