 Hello and welcome to Nursing School Explained. Today we'll go over homeostasis in the body and the regulation of pH that really helps us to regulate all of our body systems. We will look into acidosis versus alkalosis. We'll go over the different steps on how to analyze arterial blood gases and then we'll go into different examples on how to really apply this. So first let's look at the pH. A normal pH level is 7.35 to 7.45. So this is a very narrow normal range and it really helps our body to maintain proper functioning and it's really a state of homeostasis. If the pH goes below 7.35, then it's considered an acidotic state. If it goes above 7.45, then it's considered basic or an alkaline state. So these are the very basics that you hopefully remember from physiology class. So now let's see how that applies to our body system. So I've drawn out here an equation that you may remember from chemistry. So we have H2CO3, which is bicarbonic acid. And bicarbonic acid is a byproduct of cellular metabolism that can be broken down in several different ways. First of all, it can be broken down by the respiratory system by breaking H2CO3 up into H2O and CO2. So the respiratory system will break down the bicarbonic acid into water and carbon dioxide. As we know, the respiratory system is in charge of gas exchange, so it'll be in charge of oxygen and carbon dioxide exchange at the alveoli. And we'll go over it in a moment here as to how it does that. Now on the metabolic side, on the renal side here, this bicarbonic acid can be broken down into hydrogen ion and bicarbonate. So H plus and HCO3 minus. Again, we have two Hs and then CO3 right here, so this can be broken down. And the kidney will filter the hydrogen ion and the bicarbonate by either increasing or decreasing their reabsorption to balance out the pH. So now, as you can see, I have color coded here, so everything in red is acid and everything in green represents alkalosis over here. And these two systems work together to balance the pH. So typically when there's something going on with the respiratory system, so let's say the patient has a bad pneumonia, a pulmonary embolism, adelectasis, narcotic overdose, which decreases respiratory rate, there is a need to balance the pH because the respiratory system has now been compromised and so when there's something going on that's based on the respiratory system of disease, then the metabolic, the renal system will kick in to try and balance whatever is going on with the abnormalities of the respiratory system. And it works exactly the same vice versa. So the renal system, if there is something going on with the renal system where now with the metabolic system, where now the pH has got out of balance because let's say the patient is septic, they have a very bad infection, they've had major burns, they have renal failure, they have all that can be all kinds of underlying issues that I'll be discussing in a separate video that can be the cause for metabolic imbalances. So where the renal system somehow has taken an impact and now there's either too much acid or too much base in the system and then the respiratory system will try and compensate by regulating this by increasing or decreasing the respiratory rate to increase or decrease CO2 absorption depending on what's needed at the time. So in an acidotic state when the pH is less than 7.35, the body is going to try to increase the pH level. And the way we do this, it does an acidotic state, the respiratory system will increase CO2 excretion by increasing the respiratory rate. So when we increase CO2 excretion, we get rid of some of those acids and then therefore from an acidotic state we'll go back to hopefully a more normal pH state by increasing the pH level. Now on the renal or metabolic side, the kidneys, if there is an acidotic state with a pH of less than 7.35, the kidneys will compensate and they will increase our bicarbonate absorption because now we have too many acids which really represents the hydrogen ion here in our system. We will increase the absorption of that bicarbonate to balance out the acidotic state and again hopefully bring it back here into the normal. Normal state. Now in an alkaline state, the pH is greater than 7.45 so what we really need to do is decrease the pH to bring it back into the normal range. So what the respiratory system does it decreases CO2 excretion by decreasing the respiratory rate. And therefore from an alkaline state we now reabsorb we now have more CO2 in our system which we know here is more acid so now we go from an alkaline state back towards the normal pH level. Now when we look at it from the renal or metabolic side in an alkaline state which is right here basic, our bicarbonate there is too much of the bicarbonate in the system so now we need to get more towards the acidic side so the renal system will decrease the bicarbonate absorption and therefore increase the hydrogen absorption therefore balancing out this basic to the normal pH state. This really applies to ABG arterial blood gas interpretation and the first thing that we need to do is to look at the normal values. I've written these in a box in red over here and I've written big memorized. So we all know the nursing school is all about application and analysis but there are still certain things that we need to memorize in order to be able to apply the material. So this box is one of those things that you will just have to memorize. First of all pH, normal value 7.35 to 7.45 as we've just discussed over here if it's lower than 7.35 it's an acidotic state. If it's higher it's an alkaline state. PCO2 I just like to remember is the same numbers but without the 7 as the pH so it's 35 to 45 but it goes the opposite way so if it's increased if it's higher then 45 if it's acidotic if it's lower it's alkaline. Bicarbonate normal values are 22 through 26 if it's lower it's acidotic and if it's increased it's alkaline. So the pH and bicarbonate move in the same direction as so if it's higher or lower if it's acid or alkaline and the pH really moves the opposite. Again just memorize these also refer back to your professors and your textbook because values may differ by hospital, by your textbook by your professor but in general these will be much the same everywhere. So I've written out some steps here on how to go about interpreting these APGs. So first of all we're going to look at the pH we're going to look at the pH and determine if it's normal acidotic or alkaline. Number two we're going to look both at the PCO2 and the bicarbonate to see which one of them matches the acidotic or alkaline state pH. Step number three we're going to look at the opposite system so if we've now determined that let's say the the PCO2 matches the pH then we're going to now look at the bicarbonate. So that's the opposite system that's trying to compensate to try and bring the pH back into normal range. So there are three different things that can happen here. The opposite system or the EBG can be uncompensated. In that case we would have an abnormal pH and the opposite system has not responded meaning that it will be in normal range. For partial compensation the pH will still be abnormal but both bicarbonate and PCO2 will be abnormal. Meaning that now we have an abnormal pH is somewhere out of range but they're both trying so one of them is exotic, one of them is alkaline they're both trying to bring the pH back into normal. If it's fully compensated that means that the compensatory system whether it's Reno or Respiratory has kicked in and the pH is now normal but both the bicarb and the CO2 will still be abnormal. Meaning that now the pH is normalized but one of them will be over here but together they work together to bring the pH back into our normal range. So let's look into some examples to really apply this information. I highly recommend memorizing these numbers and then also memorizing these steps because then you have no problem analyzing ABG. So first example over here our pH 7.29 means that it's acidotic pH 2.54 is acidotic as well bicarbonate is 30 which means that it's alkaline. So first thing we label our pH we say it's acidotic and then we see which one of the two bicarbonate or PCO2 matches it. So in this case the PCO2 is acidic so we know that the primary offender here is a Respiratory Acidosis. These two match Acidosis and PCO2 represents the Respiratory system. Now we need to look at our compensation. So step number three the pH is abnormal and both of these are abnormal we have one acid and one alkaline. So we have an abnormal pH with both bicarbonate and PCO2 being abnormal so in this case we have a partially compensated partially compensated Respiratory Acidosis. Let's look at example number two. pH 7.49 which is alkaline PCO2 is 30 which is alkaline as well and then our bicarbonate is 24 which is actually normal. So now looking at the pH again it's alkaline what matches is the PCO2 so we know that we have a Respiratory Acidosis and now the pH bicarbonate is normal so the opposite system has not responded so there's basically the renal system has done nothing to help us decreases pH therefore it is an uncompensated Respiratory Acidosis. Example number three. pH 7.25 means Acidotic. PCO2 is 30 meaning alkaline bicarbonate is 17 meaning Acidotic. Again I determined my pH is acidic so is my bicarbonate so I know my primary offender is metabolic it's the renal system so metabolic acidosis and my PCO2 is alkaline so that means the Respiratory system is kicking in pH up so looking at my rules over here I have an abnormal pH and both of them are abnormal as well so I have an abnormal pH with both bicarbonate and PCO2 being abnormal therefore I have partially compensated metabolic acidosis Example number four. pH is 7.45 which is normal PCO2 is 31 and bicarbonate is 20 which is acidic now over here when the pH is normal it tells us that the only time that the pH is normal that means that it's fully compensated so but now how do we determine whether we were alkaline or acidotic before so if you look at this pH it's really on the alkaline side of the pH knowing that the pH goes from 7.35 to 7.45 the 7.45 is more on the alkaline side of the normal and then we look at again the PCO2 31 alkaline and bicarbonate acid so in this case because these two match although the pH is normal but it's more towards the alkaline side so we have a Respiratory alkalosis and because the bicarbonate is abnormal as well it is fully compensated so basically if you look at this back over here the pH is normal the PCO2 is alkaline and the bicarbonate is over here so those two have balanced each other out to help the system get back into normal range and then our last example over here the pH is 7.12 so it's acidotic PCO2 is 41 which is normal and then bicarbonate is 18 which is also acidotic so now we know we have to determine our pH which is acidotic bicarbonate is acidotic so we know we have a metabolic acidosis and the PCO2 is normal so the Respiratory system has done nothing to compensate so by our rules over here pH is abnormal opposite system has not responded means it's an uncompensated metabolic acidosis I highly encourage you to look at more examples either in one of your books, textbooks workbooks online to really apply this information if you know the basics of how this applies to breaking down the carbonic acid and memorize these numbers as well as these steps you really should be able to interpret any blood gas that is maybe on a quiz or that you want to practice with I am also going to have another video that explains the different causes and reasons and nursing interventions for the different arterial blood gas abnormalities and abnormalities in pH and what we can do to resolve those please leave any comments down below I appreciate those and also let me know if you would like me to review and for now, thank you very much for nursing watching and nursing school explained