Respiratory Alkalosis

what's up ninja nerds in this video today we're going to be talking about respiratory alkalosis before we get started though down in the description box we'll have links to comprehensive notes and illustrations that you can utilize to enhance your learning experience and follow along through the process of this lecture if you guys love this lecture you benefit from it it helps you please to continue to support us by hitting that like button commenting down in the comment section and most importantly subscribing all right engineers let's get right into it alright so when we talk about respiratory alkalosis what is this well we know that if we were to get an abg on a patient right we had a patient who we got an abg and came back into the computer system and got alerted okay i got to take a look at this abg see what's going on with this patient i look here at the abg and i see okay ph is 7.48 what's a normal ph 7.35 to 7.45 that is greater than 7.45 so that's abnormal and it's on the alkaline end so there's alkalemia in this case so i'm going to put an up arrow here to indicate that there is a high ph or there's alkalinia okay next thing i go down to my co2 my co2 is 28. normal is going to be anywhere from 35 to 45. that's way less than 35 so we're going to draw a down arrow in this case so down arrow that means that there is low co2 within the blood or hypocapno hypocarbia in this case the next one is you move on to the bicarb bicarb is usually supposed to be within what 22 to 26 is generally going to be the nice sweet range we're a little lower on that let's write down it is lower but let's try to figure out what the overall issue is here and we will in just a second and the next thing is we look at the po2 okay this is basically the concentration or the partial pressure of oxygen within the blood more specifically so the partial pressure of oxygen within the blood and in this case it is 45 millimeters mercury that's really low normally we want 80 to 100 okay that's normal amount of oxygen partial pressure if it's between 60 and 80 it's kind of a mild hypoxia if it's between 40 to 60 that's going to be more of a moderate hypoxia and if it's less than 40 that's a severe hypoxia and hypoxia is just low oxygen amount within the blood that's being delivered to the tissues so in this case this is low and so there is definitely some pretty decent hypoxia in this case more along the edges of moderate hypoxia so if we have this abg we know that there is alkalemia right there's an up going ph in this situation now if you guys remember how do we remember what the primary cause is if co2 is going in the opposite direction of the ph it's a respiratory disorder if bicarb is going in the same direction as the ph it is a metabolic disorder we obviously know that this video is respiratory alkalosis so we know the primary problem is respiratory and we can confirm that by saying oh the co2 is going in the opposite direction of the ph so this is a respiratory alkalosis but remember we said that the bicarb is lower okay well what happens is you're probably starting trying to compensate right whenever you have an alkalosis the ph is high if i get rid of some of that bicarb and i kind of retain some more of those protons my ph should start going down so there's some compensation and that's why the bicarb is a little bit lower in this case so in this scenario we know that this person has what's called respiratory alkalosis we can define that based upon the ph and the co2 going in the opposite direction we also know that there is some metabolic compensation but the question is was there full compensation or partial compensation partial compensation means that it didn't go back to a normal ph range full compensation means it did go back to the normal ph range it didn't go back to the normal ph range so it's a partial compensation and the last situation here is we know that this person also has some pretty bad hypoxia so there's some moderate hypoxia because they fall within that around the 40 to 60 uh millimeter mercury range so this is a pretty bad case i'd be a little nervous if i saw this abg okay so what do i have to do well the next thing i have to do is i got to figure out why is this person having a respiratory alkalosis and so we've got to go through our pathophysiology our causes but before we really really do that we have to have a basic understanding of the physiology starting from the respiratory centers within the medulla and going all the way to a breathe out co2 or bring in oxygen so how does that normally work inside of our brain stem you have these medullary respiratory centers right particularly within the medulla you have these respiratory centers so here this is going to be you'd have a midbrain pons medulla spinal cord right here's our medulla on the lower part of that brain stem there's respiratory centers there one is called the vrg and the other one is called the drg whenever someone is getting ready to start initiate the breathing process to having a normal rate of breathing a normal depth of breathing these respiratory centers should fire particularly the vrg will fire and it'll send signals down the spinal cord to activate these motor neurons in our spinal cord when these motor neurons are stimulated or activated they will fire and the fire action potentials that'll move down this axons of what nerves will nerves that are going to be going to particular muscles that are involved in breathing what are those muscles that are involved in breathing well this big sucker right here is going to be your diaphragm this is a really really important one it's one of the primary muscles that are involved in inspiration the other one are these little muscles here that are which are located between the ribs and these are called your intercostals and there's two types the external intercostals are the primary ones that are involved in inspiration whereas the internal are enforced expiration so these are the two muscles and we're going to have these nerves going to stimulate this muscle to contract and these muscles to contract and when they contract they cause the diaphragm to go down they cause the actual ribs to kind of go forward and upward increasing the space within the thoracic cavity for you to pull air in and then if you have healthy lungs you should expire the co2 out so in healthy individuals they should bring oxygen in and then push co2 out so that's kind of the normal process of how this breathing should occur now in pathophysiological scenarios like in someone who's respiratory alkalosis what's the problem well the problem is that they are just breathing off a lot of their co2 and so their co2 levels within the blood are going to be lower why is that a problem think about that if your co2 levels right for example your co2 levels in the blood are lower what happens what's that reaction co2 plus water yields what's called carbonic acid carbonic acid is a weak acid that disassociates into protons and it's a bicarb if there's less co2 because you're breathing a lot of that co2 off what does le chatelier's principle say the reaction should shift to the side where there's less amounts of that molecule in this case it should shift to the left if you shift to the left what happens to the amount of protons which are going to be present within the blood the amount of protons because you're shifting it to this side should start to decrease so in this case there should be less protons that are going to be present within the blood if there's less protons what does that mean for the ph remember it's an inverse or logarithmic relationship so in that case the ph should increase and that's where we get that alkalosis now we understand now that the problem is that they're breathing off a lot of their co2 less co2 within the blood they're having the reaction shift to the left that means that the protons are decreased and causing the ph to increase the question is is what is causing this co2 loss why are they losing too much co2 so let's think about this let's start from the center and then kind of work our way out to the lungs and just figure out causes along the way so if you think about this what if i just increase the activity of my medullary respiratory centers so i just drive up the activity of these respiratory centers and i'm having these guys fire more frequently sending more signals down causing more contraction and breathing off more co2 and causing less co2 within the blood what could be reasons that i'm hyper stimulating or really really agitating that medullary respiratory center a big one is drugs believe it or not so drugs are going to be a very very strong stimulus and what type of drugs should we be considering well one of them is going to be particularly things like salicylates so salicylates are going to be things like aspirin right so if someone is taking too much aspirin like an overdose of aspirin what that can do is that these drugs can actually hyperstimulate the activity of these medullary respiratory centers cause increased firing increase contraction of those muscles and then you're blowing off more co2 lowering the co2 within the blood other things could be things like methylxanthine sometimes there can be drugs like methylxanthine and another one so this could be salicylates methylxanthine and another one is nicotine nicotine is also another one that can also cause a lot of hyperstimulation of that medullary respiratory centers so these are three particular drugs that we would want to be thinking about that could be hyperstimulating this medullary respiratory center the next one is infections you know particularly like gram-negative sepsis when someone has particular bacterial infections and you know what type of bacteria or the really really nasty one it's when you have the gram-negative bacteria so gram-negative bacteria particularly in what's called sepsis so if someone has sepsis secondary to gram-negative bacteria what happens is some of the toxins and the lipopolysaccharides and things like that can actually cause hyperstimulation of those medullary respiratory centers causing them to fire more often causing more contraction of your respiratory muscles causing you to blow off more of that co2 should make sense right so sepsis would be another reason particularly gram-negative sepsis the next one is interesting very very interesting so you know whenever the liver is functioning normally it can actually metabolize uh certain substances and like particularly breaking down ammonia making it into urea whenever there's liver failure so let's say that someone has liver failure particularly to the point to where that liver failure has become so so bad where the liver isn't able to deal with that ammonia so much and it causes some problems with the central nervous system and because it's causing problems with the central nervous system the primary thing is called encephalopathy secondary to a hepatic cause so apatic encephalopathy so what happens is normally the liver should be able to utilize ammonia right and convert this into urea but if the liver is damaged it's not able to perform that task and so instead this activity doesn't occur and so you build up a lot of ammonia and ammonium ions well these when they travel to your central nervous system are very strong stimulants of that respiratory center within the medulla causing increased firing blowing off more of that co2 so that could be another reason which would be liver failure particularly hepatic encephalopathy where they're not able to clear the ammonia into urea the next one that you want to be thinking about this one's actually very interesting but it's it's more again increasing the activity of those neurons and how it does this is a condition called hyperthyroidism so when someone who has hyperthyroidism and they're producing a lot of t3 and a lot of t4 right in this situation what does this do these increase the basal metabolic rate of multiple different types of tissues as you increase the metabolic rate of multiple different types of tissues what can that do that can increase the action potentials the excitability of these cells and so if you have an increased basal metabolic rate what that should do is increase the activities of these medullary respiratory centers and cause them to fire more frequently so that could be another reason and someone who has what's called hyper thyroidism particularly a very severe type of it where there's a crisis or very bad sometimes we call this thyrotoxicosis so more in the very severe forms of hyperthyroidism like thyrotoxicosis could you see this type of effect there's one more thing that i actually don't want you guys to forget as well and that is in pregnancy sometimes in females whenever they're pregnant their body obviously is dealing with a lot of different types of hormones and one of those hormones that has a very profound effect on the the actual regular respiratory centers is progesterone so sometimes in pregnancy when there is some type of pregnancy here there can be large amounts of progesterone that's being released so sometimes very very large amounts of progesterone in pregnancy can also be a very strong stimulus for those respiratory centers and lead to that increased firing of these nerves and causing you to blow off more of that co2 so that could be another one to also think about whenever there's high levels of progesterone secondary to what most commonly you want to think about pregnancy okay so those are some things that are very very strong respiratory stimulants what else though well there could be other areas of the brain that are stimulating these respiratory centers you know your hypothalamus your hypothalamus has a pretty good influence on these medullary respiratory centers hypothalamus is a part of your limbic system right so whenever there's some type of like pain um anxiety fearful types of responses that your body is being exposed to that can activate that hypothalamus and that hypothalamus can come down and send signals to those medullary respiratory centers saying hey i need you to fire more frequently because what i want you to do is breathe quicker so you can blow off that co2 bring more oxygen in so you can get a lot of oxygen to those muscles so that you can run away from whatever whatever that scenario is so in these situations i want you guys to also really remember that hypothalamus has a very big effect and so things that can really affect the hypothalamus is kind of anxiety so if there's a lot of types of anxiety pain fear these are limbic types of things that can stimulate the activity of the hypothalamus if the hypothalamus is very active it's also going to stimulate that medullary respiratory center and cause increased firing as well so again don't forget about that good old hypothalamus one more thing just like hyperthyroidism right you're increasing the basal metabolic activities you're causing more firing of these neurons what if someone has a fever they're pyrectic right they're having pyrexia so they're having a good fever you're popping a fever greater than 100.4 100 so greater than 100.4 degrees fahrenheit is technically what we consider to be fibril if someone is having a fever fevers can also increase your basal metabolic activity also there can be some again more stimulation of the hypothalamus as well but what happens is this increase in basal metabolic rate and this fever situation can cause both double simultaneous stimulation of hypothalamus as well as maybe increasing the activity of those neurons within the medulla so as you guys can see what's kind of like the big central area where a lot of these problems are coming it's at that medullary respiratory center so a lot of this is cns issues where there's hyperstimulation whether it be due to drugs gram-negative sepsis hepatic encephalopathy hyperthyroidism fever or some limbic situations like fear anxiety pain regulated by the hypothalamus or even in situations like pregnancy where there's lots of progesterone production okay the only other one which is kind of controversial here is that sometimes if people have mid-brain tumors that can also lead to this type of hyperventilation response we're not going to get too much about it but just realize that could be another potential cause so there's one more scenario that i also want us to really think about it's a very interesting one and it's actually sometimes we want to actually cause an alkalotic kind of a reaction in people who have what's called high intracranial pressure so sometimes when someone has for whatever reason elevated intracranial pressure this can sometimes be very very very scary so high icps intracranial pressure for whatever reason maybe there's a tumor maybe there's a bleed maybe there was an infarction there that caused a lot of cytotoxic edema around it but regardless there's high endocrine pressure and the fear with this is that whenever there's high icps it can cause the brain to herniate out right they can cause compression of the brain stem you lose function of your respiratory activity your cardiovascular centers and then the patient can die so what we want to do is is reduce the icp and one of the ways that we reduce icp is you have to think about the brain it's it has a skull right and then inside is brain tissue cerebrospinal fluid and blood the only way i can reduce the intracranial pressure is by reducing one of those three things i can reduce the amount of cerebrospinal fluid by putting in a shunt i can reduce some of that actual cerebral edema by certain hyperosmolar agents or i can reduce the amount of blood flow that's going to the brain and that can also reduce the icp so sometimes in people who have high intracranial pressure what we will do is we will actually hyperventilate them kind of temporarily we don't want to do this too long but we'll hyperventilate them and have them blow off more of their co2 why this is important is when you hyperventilate a patient what does it do to the co2 levels within the blood it lowers those co2 levels in the blood you know what that does to the actual cerebral vasculature in the brain what it does is it actually causes the cerebral vessels to constrict so it causes cerebral vasculature vasoconstriction and by doing that you try to reduce the amount of cerebral blood flow if you reduce cerebral blood flow you know what the purpose of that is it's to reduce the icp but you only do this temporarily you don't want to do it too long because if you reduce the cerebral blood flow for a long time what could you do you could cause a stroke so again the reason why we would do this is that someone is having an icp crisis and we're actually trying to hyperventilate them iatrogenically so that could be one particular reason we call this kind of like iatrogenic hyperventilation and we're actually doing this because we want to blow co2 off to cause cerebral vasoconstriction and then reduce that icp another thing that could be iatrogenic hyperventilation is that you actually have someone on the ventilator and you're increasing the respiratory rate right you have the ventilator settings wrong and they're breathing too fast maybe on the ventilator this could be one reason high icps and you're trying to do this on purpose the second reason is that they're on the ventilator and when you have them on the ventilator you're actually having the settings wrong and so maybe you set their respiratory rate to be high because you want to blow off more co2 and bring in lots of volume but when you do that you blow off too much of their co2 and so their co2 levels in the blood drop and then that can cause that respiratory alkalosis so there could be two ways that we can iatrogenically hyperventilate a person one is we're doing it as an intervention and the other one is we just didn't set the ventilator settings properly and we're having them breathe too fast blowing off their co2 so those are two other reasons there to think about for someone having respiratory alkalosis the last one that i really really want you guys to remember because these are the scary ones and more likely what's going on with our patient who has this hypoxia so far all we've been talking about is the reasons of why this patient has lower co2 within the blood but we didn't mention why this patient is having low oxygen in the blood and that's scary let's think about why think about the lungs at this point you know whenever someone has what's called pulmonary edema they have lots and lots and lots of fluid that may be kind of sitting between the alveoli so let's say here i kind of expand and draw like a little alveoli here i'm going to draw a little alveoli and then here you have the alveoli and the blood vessel the pulmonary capillary in this case if someone has a lot of edema right a lot of fluid which is accumulating between this space and that interstitial space what's that going to do to the actual movement of co2 so co2 won't be able to cross as much right and what else oxygen won't be able to cross as much and so because of that what will happen to the amount of oxygen that's going to be present within the blood the oxygen level in the blood will drop so that's one particular reason what is this reason here called again this one where there's lots of fluid could be in situations like pulmonary edema and you see these a lot whenever you're just giving too much fluids to someone or they have heart failure the other situation is what if their actual lungs have a lot of fluid inside of them so i drew another alveoli let's say i draw another small little alveoli over here that i kind of expand on here's another little guy and i have instead of fluid in the interstitial spaces i have fluid that's actually kind of in the lungs and a little bit inside of the spaces out there and something like some patients who have what's called acute respiratory distress syndrome that could be another reason and again this is altering the movement of oxygen into the blood and so less oxygen is present within the blood what could be a reason for this this could be acute respiratory distress syndrome another thing is what if i have an infection i have an infectious process a lot of pus a lot of white blood cells a lot of material in here that is affecting the movement of oxygen across the uh this respiratory membrane what could that be caused by ammonia so if someone maybe has a pneumonia as well this could be another potential reason so a pneumonia may alter that exchange of the movement of oxygen from the alveoli into the blood okay and the last one here is what if i have like a clot so let's say that i take this blood vessel here for the sake of it and expand it a little bit so we have one more area here as a potential cause and i put a little clot in that blood vessel right here okay and here's the alveoli that i want that blood to go to i wanted to go up to this little alveoli pocket here but i can't and why why can't i get blood to this area well the reason why i can't get blood to this area is because there's an emboli that's blocking the blood flow from getting there so now blood isn't actually moving into this area and so now oxygen even though it's moving over it's not getting picked up by red blood cells because the red blood cells are stopping proximal to that embolus and that also is going to be a problem here so pulmonary embolus could be another potential reason of what for what what is the whole purpose of all of this stuff that we just said whether it's fluid whether it's an infection or whether it's actually a clot all of these things affect the movement of oxygen from the lungs to the blood and so the overall effect of all of this stuff is hypoxia hypoxia is a bad bad man why because you know what hypoxia does especially when we get it to like less than 60 millimeters of mercury remember we said that usually we want it like 80 to 100 but if it's less than 80 between 60 to 80 is really where it's kind of mild if we start getting less than 60 we're getting to the moderate sites of hypoxia what this does is hypoxia is actually a relatively strong respiratory stimulant on these little receptors you know there's little chemoreceptors that are located near your carotids you know you have what's called the carotid sinuses and then you have the carotid bodies well the carotid bodies and the aortic bodies there's also two of them there's carotid bodies and aortic bodies they have little chemoreceptors in them and they pick up on low concentrations of oxygen in the blood due to pulmonary embolisms ards pulmonary edema or even pneumonia in these situations what happens is they stimulate these peripheral chemoreceptors what are these things here called these are called your peripheral chemoreceptors and these are located where just so that we're clear here they can be located in the aortic bodies and they can also be located in what's called the carotid bodies and when these are stimulated by low oxygen a particular concentration in the blood guess what this does this sends messages via particular nerves the glossopharyngeal nerve and the vagus nerve comes to your medulla and guess what it says to the medulla hey there's low oxygen in the blood that means that you're not ventilating properly i need you to breathe faster and deeper so that you can pull more oxygen in so what does it do as a result of that stimulates your medulla you fire more you cause more contraction of the diaphragm and the external intercostals you breathe more of your co2 off but if you haven't resolved the pulmonary edema you haven't resolved the arts you haven't resolved the pulmonary embolism or pneumonia guess what you're still not going to be getting oxygen into the blood so you're going to stay hypoxic and that's the problem here so as a result of this hypoxia it causes a kind of reflex respiratory alkalosis in this situation because they're blowing off co2 because the hopes is as they breathe faster and deeper blowing off co2 they'll bring in oxygen but if you don't fix the issue it's not going to change this would be our pretty much our pathophysiology our causes truly understanding what respiratory alkalosis can be due to how do we diagnose all of these again we can utilize our abg and then use our entire pathophysiological approach that we just took here trying to figure out what the problem is now that we've done that what do we got to do i got to treat this person i got to figure out what do i have to do for them so how do i treat this person let's think about this first things first let's go to what we started with central problems there's something centrally going on some of these we can fix not all of them but some of them the first one that i'd like to fix is what about drugs you know there's this is a common exam question that they love to ask whenever there's a salicylate overdose especially aspirin particularly in aspirin what is the the antidote that you actually give to reverse this you can give this an iv po generally this is kind of that classic question that they'll bring up on your board exams of the particular antidote that you can give them methylxanthines nicotine not really too worried about that what if they have sepsis what if they have gram-negative sepsis antibiotics right not too hard to think about that so if they have gram negative sepsis you're going to treat them with antibiotics as well as stabilize their hemodynamics obviously okay but if you treat the underlying issue that should help to resolve some of these problems hepatic encephalopathy what do we do for that one hepatic encephalopathy you know you can try to reverse that but you have to decrease the amount of ammonia so what do we do for that usually in someone who has like high levels of ammonia secondary to that hepatic encephalopathy we can give them drugs called lactulose or we can also give drugs like rifaximin okay the next thing what if someone has hyperthyroidism not too hard to think about you give them anti-hyperthyroid medication so if someone has hyperthyroidism you're going to do what you're going to give them drugs like propothyluracyl or methimazole okay we're just going to put anti-thyroid medications but you guys know because you're ninja nerds that this would be things like methimazole this would be things like prothyurasil a lot of other different stuff right iodine solutions particularly that help with ablating those thyroid follicular cells nothing that you can really do with pregnancy that's just a part of the process fever if they have a fever what can you do with a fever you give them tylenol right so if they're febrile you can give them tylenol that can just treat them empirically but you have to figure out why are they having a fever is this just a central nervous system reaction or is this an infection i can treat them with tylenol i can try to give them things to cool them down but if it's an infection i got to treat the underlying infection with pain anxiety fear again sometimes it's just telling the patient hey let's calm down don't get too anxious sometimes to have them breathe into a paper bag to help to retain their own co2 sometimes you have to give a little bit of an anxiety kind of medication to calm them down if you need to as well so those are things that you want to be thinking about um the next thing is what if they're on the ventilator and you're just breathing too much for them decrease the rate on the ventilator not too hard to think about right don't have them breathe as much of that off what can i do about this icp it's kind of something i have to do temporarily so they don't herniate so again nothing i'm really going to do there now these guys this is stuff that i can try to fix because this is going to eventually cause problems because again they're going to start breathing really really fast really really heavy to try to blow off co2 and bring in oxygen but the muscles are going to get weak they're going to fail and then they're going to go into respiratory failure because they can't actually utilize those muscles because they're exhausted so how do i fix these very very simple pulmonary embolism you get rid of the clot how do you get rid of a clot with a pulmonary embolus well it depends right you can give them things like heparin heparin is one option sometimes they even offer tpa tissue plasminogen activator to bust up that clot and the other one is sometimes they can do what's called a imbilectomy where they actually mechanically go in and remove that embolus pretty straightforward right ards what do you do for them you just have to properly ventilate them so ours is more of kind of a disease where you just have to maintain their actual mechanical ventilator for like maintaining their activity on the mechanical ventilator so sometimes this is just proper ventilation okay allowing those lungs some time to heal as well as figuring out the underlying cause for their arts pulmonary edema this is a big one you see this one a lot okay pulmonary edema is a lot of fluid in that interstitial space if i give a drug that can pull some of the fluid out of there that may reduce some of that edema and help me to get some more oxygen across those lungs so what could that be good for absolutely no no i'm just kidding it'd be good for something like diuretics lasiks right things like that could actually pull some of that fluid out of that interstitial space so things like loop diuretics could be helpful in this scenario and then the last thing here is if they have pneumonia it's pretty straightforward you give them what you give antibiotics okay so it's relatively straightforward relatively simple to help in this scenario now there's one other thing that you can do if you have someone on a ventilator and maybe they just have this increased kind of respiratory drive where they're just they feel like they have to keep breathing because they need this respiratory drive to continue to keep trying to take and breathe over the ventilator sometimes what you can do as the last thing that i want to write down here is that sometimes if a person is on the ventilator and maybe you're not hyperventilating but maybe you're they're actually requiring more breathing and they're having to breathe over the vent they're having to breathe really really fast and they're blowing off lots of their co2 sometimes what we can do is we can give them drugs to kind of shut down their respiratory center and say hey respiratory center stop firing for a little bit and let the ventilator do the work let the lungs rest so sometimes if a patient is breathing over the ventilator so they're over breathing the ventilator maybe it's not you who's actually causing them to have a higher respiratory rate maybe they're breathing over the ventilator over breathing the ventilator then maybe what you have to do is give them some medications to decrease their respiratory drive and what could that be opioids and sedatives okay so you can give them things like sedatives propofol ver said or you can give them opioids analgesics okay things like fentanyl and that may suppress the respiratory center and cause them to not breathe as hard and as fast so that would conclude our understanding of respiratory alkalosis all right ninja nerds so in this video we talk about respiratory alkalosis i hope it made sense i hope that you guys enjoyed it and hope you learned a lot as always ninja nerds until next time [Music] you

Channel: Ninja Nerd Lectures

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Length: 32min 58sec (1978 seconds)

Published: Wed May 19 2021