greetings guys Mark Boswell Boswell emergency medical education technology coming at you with a short little video here to help get you ready for some of your C preparations um I want to talk about preload and afterload and I'm doing this as a separate little video you all can watch before the cardiac lecture because I feel we really don't have a lot of time to go through this and in depth as much as I'd like to during the cardiac lecture when we do it I'm still going to go through it when we do a cardiac lecture however I want to talk about it a little bit separate here in that way especially like if if you go to the shock lecture uh it jumps right into pre-load and afterload pretty quick and if you not had the benefit of seeing the cardiac lecture to hear it you might be a little at a loss for things so we're going to go over that here for the next few minutes and talk about this and one of the reasons we go through this is because again teaching these classes my goal is to get you as prepared as you can be understanding concepts that way you can apply them in different scenarios so not just teaching um exam questions not just teaching you know specific diseases and signs and symptoms but understand the concepts and important to a lot of our cardiac issues and some of our shock issues as well too is understanding pre-load and afterload one of the things I did and researching this because I'm no ICU nurse you know I'm just an ER guy we just need to keep it simple right one of the things I found is there's a lot of inconsistencies in how people are explaining pre-load and afterload I've pulled some videos on YouTube some other Educators materials and I still was really kind of confused I even looked at some the ENA materials like the shees emergency Manual of nursing as well as uh the emergency nursing Core Curriculum it was still kind of vague and not really clear what we're looking for there and I really felt it could be made a lot more simple to understand so this is what I'm going to give you the simple version the down and dirty what you need to know we're not shooting wedge pressures in ER we're not inserting swans we're not checking PA pressures things like that we don't need that we need to understand how the heart as a pump works and how we can adjust it or boost it depending on what the pathology or what the problem with the heart is and where it's pump is having an issue okay so let's talk about pre-load and afterload there's only one slide for this show so there's not a lot for this and this is a slide feel free to screenshot this if you want and save it for your study files or whatever but it's got all the Talking Points I want to talk about with pre-load and afterload and I'm going to really dumb this down to make it really easy to understand you notice there's not a single number on this screen we're not wor about a single normal pressure okay we can know what's going on with the heart what its problem is just by knowing what the condition is um whether it's more something that we need to manage the preload or something we need to manage the afterload because that's what we're looking at clinically is what do we need to do clinically to boost the cardiac output depending on what their disease or their injury or their condition is all right so let's start with preload over on the right side now preload is defined as the amount of stretch of the ventricles at the end of the diast so preload is a pressure I'm sorry yes preload is a I'm sorry preload is a volume because it's a volume of stretch as the right ventricle or the left as it fills the blood in this case from the vnea right ventricle or the left ventricle coming in from the um pulmonary vein I'm sorry coming in from the left Atria as it fills there's a amount of stretch like a balloon on the ventrical walls and that filling or that stretch is the preload okay that's it's it's an amount of stretch and the more stretch the ventrical has the better its output is in any disease state where that stretch is not enough and there's less output and that's would be too little preload oops I spelled that wrong preol load so too little preload is when there's not enough volume filling up the ventricles and so therefore the ejection or the amount out is inadequate one of the big ones we talk about is the right ventricle if you have a right ventricular mild cardial infarction part of that right ventricle wall is damaged from the infar and so as the blood comes in here and fills it it's not able to it can stretch the blood comes in but the damaged part of the wall is not able to contract to get the blood out so they are low on on their preload okay because they don't they can't get enough tension to generate that pressure now a person who's also hypovolemic from fluid loss also has a low preload because they don't have enough blood in their system to come in through the vnea and Into The ventricle to stretch it okay so too little preload has to do with how much volume or how much fluid is coming in to The ventricle how do we fix that well it's a volume problem you give fluids so and that's why we talk about in class our right side Mis or our right ventrical Mis if they're hypotensive the treatment is not to put them on a presser the treatment because it's it's a preload problem the right ventricle is damaged is to give some fluids small boluses we give these small 200 250 CC boluses or maybe even less forcing a little extra fluid in the system to help stretch that ventricle a bit more which gives it a better ejection okay so that's too little preload that's when is preload deficient it's either due to a right side Mi usually or to a volume problem they're they're hypovolemic maybe they've lost a bunch of blood maybe it's a trauma patient okay now on the other side of the coin who has too much preload preloads of volume who has too much volume that's typically our CHF patient so if it's a volume Surplus how do I get rid of the volume well our main state of therapy is give them some lasx froide how does that give rid this Surplus plus volume it takes away some of the excess circulating fluid in the vascular system it reduces the volume other things we can do Morphine now morphine is a pain medicine it's an opiate if someone's an acute CHF it kind of works well as far as having some um it reduces some stress and some anxiety and maybe they having some chest pain works with that but morphine also has a principle which it's kind of still being debated and there's not conclusive evidence but morphine has been for a long time considered a bit of a Venus dilator and if you dilate the Venus system some that makes that tank of the V the Venus system is like a tank it's holding all your blood it makes it bigger so blood pressure goes down so you're kind of decreasing that volume or that pressure so morphine is a Veno dilator nitroglycerin also at certain dosages is a Veno dilator and it also reduces that preload so too much preload means too much volume how we going to fix that we're going to reduce the preload Lasix morphine Nitro those are your three standard simple go-to agents all right let's look at the afterload so the afterload is the amount of pressure The ventricle has to generate to force the valve open and the blood out to the periphery okay that's so that's the beginning of syst and this is closely related to the systemic Venus resistance or I'm sorry systemic vascular resistance and the mean arterial pressure is basically the resistance okay how much does this ventrical have to squeeze what pressure does it need to open the valve and get the blood out all right so a person who has too much after load there's too much resistance to get the blood out and get it functionally circulating to the body so that's a high blood pressure this is your person who's having a hypertensive issue a hypertensive crisis or emergency so how do we reduce that svr or that map a vasodilator any of our antihypertensive agents will reduce that and so therefore the heart does not have to generate as much pressure to get the blood out all right so who has too little afterload so that's a person who has a very low resistance out there this person's hypotensive okay these are commonly our states like our distributive shocks which we'll talk about in the shock lecture distributive shocks are those where something is causing the vascular system to dilate and when the vascular system dilates the pressure goes down we've got three main compon three main members of the distributive shock family our septic shock our anaphylactic shock and our give me a second I'm gonna think of the third one in just a minute I'm doing this video right on the fly right now so I'm sorry I don't have any notes in front of me I'm doing this all from the top of my head but anyways these these oh I'm sorry neurogenic shock neurogenic septic and and um anaphylactic all three of those cause a massive vasod dilation and so therefore the blood pressure goes down the mean arterial pressure how do we fix those we put them on a vasopressor we tighten up those blood vessels we get those blood vessels out here nice and tight we get them back down to their normal size the pressure goes up it can allow the heart to profuse itself especially through the coronaries as well as the the end organs okay so summary excuse me preload is a volume has to do with how much stretch at the end of diast when the ventricles are full how much stretch how expansion is on that ventrical wall and that stretch helps augment the cardiac output if you've got too much pre-load you have too much stress that's a volume problem that's your CHF person get rid of the volume give a preload reducer like Lasix morphine Nitro if you don't have enough preload means you don't have enough stretch preloads a volume how do I give more volume I give some small frequent IV Bolis Ivy fluid bises after load think of it as the resistance to the ventricles it's a it's a pressure reading okay too much afterload too much pressure too much blood pressure hypertension give a vasodilator to little afterload like a Distributive type of shock with all this Vaso dilation we put them on a Vaso presser to tighten those vessels up to increase that pressure to allow for a good coronary perfusion as well as our end organ perfusion all right guys that's your pre-load and afterload in a nutshell there are no numbers here there are no numbers on the ceen exam I promise you that all the questions Cen would talk about here's some type of cardiogenic shock or right side Mi how would you help Inc encourage cardiac output without compromising it where are you need do you need to treat the preload or the afterload how do you boost preload and how do you reduce preload how do you boost after load how do you reduce after load it's really that simple guys you notice there's only there's only four boxes here you have too much or not enough too much or not enough all right I hope this is helpful to you if you attend one of the classes we do one of the classes I do you're going to hear this again especially under the cardiac lecture and under the shock lecture and if you are listening to this before then you'll be able to tie these pieces together better when we get there all right Mark bosel I'm going to sign off here I'm gonna post this this soon as I can for you guys let me know what you think uh let me know if this kind of made some sense to you kind of help tie the pieces together maybe made it simple for you I hope all right until then y'all stay safe and be well