Fluid and Electrolyte Management in Surgery

how do you manage fluid and electrolytes how do you manage hyponatremia what electrolytes are important in this surgery tutorial we're going to cover all of those questions and everything else about fluid and electrolytes so let's do it welcome back my name is dr. Eric Pearson and I'm so pumped that you're joining us for another video I hope that you've enjoyed the first few on the metabolic response to injury the surgical nutrition videos if you haven't actually seen those yet go ahead hit the cards up here if you haven't had a chance to subscribe go ahead subscribe then you'll know when all these videos are coming out you know in this Kovan 19 pandemic crisis I figured I loved educating and that this was one of the best ways to scale surgical education I've always wanted a resource that I could go to and quickly get some knowledge that I can harness between cases or on the walk in from the car so I'm making these videos 15 and 25 minutes covering the core subjects of surgery so whether you're a medical student or you're a resident a fellow a surgeon resetting their board exams I'm hoping getting through these basics is really providing you with a good foundation in general surgery so in this surgery tutorial on fluid and electrolytes we're gonna cover that chapter that I'm sure you've skipped a few times I probably didn't read it until I was a third-year resident going into the ICU again and I knew that I just had to know all of these values and why they were important so today we're gonna go over the fluid and electrolyte the obligatory losses and the needs we're also gonna go through hyper hyponatremia hyper hypokalemia the calcium's Matic Foss all those really important values so when you get that BMP you're gonna know how to interpret it you're gonna have a good reason for getting it and to know what you're gonna do with the results so without further ado let's jump into the video for today as always we want to review the question that we ended with and so on part three surgical nutrition if you didn't see that go ahead hit the card up there part three was on TPN indications in design where we covered all at EPN and how to order it design a basic formula for TPN which is you should know that for your board exams how to at least get started and also for taking care of patients and understanding all those nutritional aspects of the ICU care and even in that post-op care on your patients on the floor so well let's go to that question so this is a 25 year old 85 kilo male admitted to the surgical ICU with an open abdomen damage control surgery he sustained a solid organ injury of most multiple segments of his small bowel mesentery required resection he's now in multiple discontinuity and what I asked was to write up a basic TPN solution for this patient and what are some of the major considerations of his ongoing TPN needs all right so to answer this question definitely check out that video we're not gonna go to all the numbers here but the first thing I wanted you to think about is is this guy have a good indication for TPM well yeah Valon discontinuity you know he's gonna be NPO for at least five to seven days we knew that he was pretty basically healthy but still he's gonna definitely hit that threshold for needing parenteral nutrition secondly think in terms of fluid in energy so when we're designing TPN we think of fluid first so in this guy we're gonna do the four to one rule that's gonna give us our fluid needs I'll let you calculate on your own okay and then when we go in the energy we're gonna say okay critically injured guy we're getting probably previously healthy 30 kilocalories and then once we determine that total caloric need we're gonna need to give about 60% of carbohydrates and we'll do that by calculating our percentage d'être dextrose solution we want to give 30% lipid we're gonna want to increase the amount of those omega-3 of those anti-inflammatory fatty acids and the lipid component and then when we go to the protein we're gonna want to be about 1 to 1.5 grams per kilo now when you do all those calculations you'll have a good simple design of your TPM to that we're gonna maybe add some daily vitamins we're gonna want to add your micronutrients we might want to add an inch to antagonist might want to add some insulin if he's had hyperglycemia and then we're gonna want to have a really good understanding of how we follow this going forward and that gets to the second question so what are the major considerations one major consideration is sky as an open admin he's in discontinuity he has a vac that's gonna be draining fluid he has probably needs a gastric tube which is draining fluid so we're gonna want to really closely monitor what his blood pressure heart rate urine output are and how his you know overall fluid status is to determine those fluid needs you know secondly is as we get further along in the ICU course we're gonna probably want to do some indirect calorimetry we're gonna want to calculate as RQ find out are we over/under feeding it is he gonna need more calories per kilo is he going to be in one of those critically injured patients that's up at 35 or 40 Killick house grand per day and we're not going to know that unless we do in our queue so if you need to go back to that video again go ahead hit that card you get back up into the fluid and energy we talked about how to calculate the RQ what it means why when you burn glucose it's a RQ equals one and while you burn the fat like palmitate the RQ is 0.7 so if you go watch that video you'll totally crush it and now let's get on to the TOC fluid and electrolytes let's do it all right so fluid and electrolytes this is what I like to refer to as the basics of the basics this is something that you do in every single patient every single day so you gotta know what's going on with fluid and electrolytes so first we're gonna talk about the body's fluid in its compartments second you're gonna be confident in understanding all of the electrolyte disturbances hyponatremia hypernatremia hypokalemia hyperkalemia hypocalcemia hypercalcemia we're gonna go through magnum phosphate will acid-base we're gonna get it all in and third is you're gonna want to know how to fix these electrolyte disturbances and we're going to focus on a couple you know sodium is one of those really difficult ones where you have hyperosmolar or hyperbole or hypo and hyper nutri mia and we're gonna get through all that so I hope you've joined with me the whole time and towards the end we're gonna put it all together and I think you're really gonna get a lot out of this video all right like every video we like to ask why so why is important to learn this it's important to learn this because it's something we do every day you can't just click that d5 half an S with 28 K it's 75 milliliters per hour and just hope it's gonna work you got to know that when you get that BMP and all of a sudden the sodium is 125 where the sodium is 117 and that elderly patient who had a fall and came in with the TBI how are you gonna replace that how are you gonna fix it you know when you have that patient who comes in with a potassium of 6 what does that mean how are you gonna fix that when you have the patient who's hi pal Kelsey make what does that mean hypomagnesemia or low phosphate what does that mean how are you gonna fix it so understanding the fluid compartments the body and the fluid that you give how that's distributed as well as the electrolytes or something as surgeons that we need to know how to do every day you can't just look and hope that the number turns red in epic or whatever a lot of electronic health record you use you got to know the numbers you got to know the why all right so let's go for the references the major reference for today is Norton's surgery I think that for the basic chapters Norton's is probably the best reference so if you're going to get a textbook and you're going to use it as a reference to study the basic science of these core surgical medical knowledge topics I think Norton's is the way to go when we get into the clinical topics I'll be referring to sabatons I'll be referring to top knife I'll be referring to a few of the other textbooks and reference books things the ones that I love and but for this one go back to Norton's these chapters they're dense but they really have what you need to know to be confident in understanding these basic building blocks of surgery all right to kick it off we're gonna look at the compartments of the body now this is important why is it important it's important because as we'll talk about the fluid that you give whether it's d5 water or normal saline or 5% albumin or blood that fluid that we give distributes to different compartments and so if you don't know what compart the compartments are what percentage they are in the body and where that fluid goes you're not going to know what to do in what situation so you have that patient comes in with one liter blood loss right how do you replace one liter and how much volume do you have to give all right well you're gonna know in 10 minutes from now you're gonna know that answer okay so when we look at total body water it can change with age and it can also change or gender but look at it is about 60 percent of total body weight is water now that changes a little bit so when we look at newborn so I take care of newborns as a pediatric surgeon and about 75 to 80 percent of their body weight is water and this decreases with age once you get to one-year-old it's about 65 percent of weight is totally bonded water and then once you get up to adulthood or late adolescence it's 60 percent of total body weight is water for males and then about 50 percent for females when we take that sixty percent that sixty percent of total body water is divided into two basic compartments you have your intracellular which is the majority that's gonna be 40 of the 60 okay and then you have the extracellular which is 20% and so those two together make up total body water forty percent for intracellular 20% for extracellular and each of those compartments have different electrolyte distributions when we look at the intracellular component so that's the majority the major cation is potassium now this is the opposite when you get to the extracellular compartment which makes up that 20% and that's where the major extracellular cation is sodium and the potassium level is very low and you can see that right here now when we divide the extracellular compartment up we get into the plasma volume which is five percent of that total twenty and then you get into the interstitial volume and that's 15 percent in the constituent acheived of each of those that's important is not so much an electrolyte but it's albumin so in the plasma where we measure albumin we know that it's concentration is about four milligrams per deciliter when we look at the interstitial volume we know that it's much less than that it's about one milligram per deciliter all right so those are the those are the percentages so total body water sixty percent that sixty is broken down and a 40 percent intracellular 20 percent extracellular that exercise is broken down into 15 percent interstitial five percent different fluids have a different volume of distribution so when you give a particular fluid it is going to spread out into a particular volume okay now let's take total body water so that's 60% of our total weight what fluid distributes across that entire space so that's d5 water so if you give d5 water that's going to distribute over the total body water compartment and so let's take the next volume so that would be our extracellular volume that's 20% of our total body weight and what fluid distributes over that and so that's gonna be normal saline so normal saline is isotonic to our extracellular volume so it's going to distribute over that compartment and lastly let's take our plasma volume so what's going to distribute over our plasma volume so that's going to be 5% albumin so when you give 5% albumin instead of distributing over all of total body water it's gonna stay within our plasma volume or 5% of our total body weight and this is going to give you an idea we're gonna do a clinical scenario where when a patient comes in with blood loss and you choose a particular fluid to give that patient how much fluid are you gonna have to give to replace that blood loss so let's get into that so let's say that you have a 60 year old male large volume hematemesis in a history of esophageal varices you're estimating that he's lost about a liter of blood as he's in stage 2 shock so to replace this blood loss how much D 5 water would you have to give versus normal saline versus 5% albumin so put the pause button on go ahead see if you can calculate this out and think about how much of each of these fluids they're gonna need to replace that one liter of blood okay so in order to find out the volume that you have to give we can do a pretty simple calculation so that's the volume and fuse is equal to the expected compartment increment divided by the normal compartment volume multiplied by the volume of distribution for that particular fluid and so we can go through this for each of them and then you'll have a really good idea of how this works with the flue that you're giving in the resuscitation Bay so how about for d5w so our expected compartment volume increment is one liter we lost the liter of blood and we want to give a liter okay so we want that to increase by a leader we divide that by the normal compartment volume so the normal compartment volume of plasma is five percent of seventy kilo so that's going to be 3.5 liters so that's 3.5 then you multiply that by the volume and distribution of that fluid or 42 liters so if you want to replace this 1 liter of blood with d5w you're gonna have to give 12 liters then you don't want to do that why do you not want to do that it's gonna spread over the whole total body water compartment and so you're gonna put a ton in the interstitial volume and your that person's gonna be the Michelin Man all right so let's go to the next one how about normal saline so let's go to the next one how about normal saline when we do normal saline our expected volume increment is again 1 we divide this by the normal compartment volume so 3.5 again five percent of 70 kilos we multiply that by the volume of distribution for normal saline which is the extracellular volume so that's 14 liters and we get 4 liters so that means if you want a one liter increase in your plasma volume your blood volume you're going to want to have to give 4 liters of normal saline and so you can say well where does that additional three liters go that it's gonna go to the interstitial fluid okay and that's why all those wrinkles go away when you resuscitate somebody with a ton of normal saline all right so now let's look at colloid so if we take 5 percent human what's gonna happen so you get one liter divided by 3.5 liters which is our compartment volume again you multiply that by the volume of distribution for albumin 5% and what do you get you get one liter alright so now there's a whole discussion about what's better for trauma resuscitation colloids versus crystalloids we're not going to get that into that right now we'll get into that and maybe another talk but for your understanding this is how you can determine what volume you need to infuse of what fluid and where that fluid is gonna go I'm gonna pop over here for a second and now we can talk about what our obligatory fluid losses so if you don't do anything how much fluid II just gonna lose and how much fluid you're gonna have to replace so this is your daily need of fluid and electrolytes so first you gotta make urine no no matter what you're still gonna pee and your normal you're in production is gonna be about a half a mil per kilo per hour to a mil four kilo per hour now if we look at our GI losses and we'll go into each of these organs and how much fluid they're actually producing but the majority of gastrointestinal secretions are reabsorbed and so you're really only losing about 100 to 200 milliliters of fluid for our gi losses and then we have our n sensible losses and so that's 8 to 12 mils per kilo per day and this is gonna change so it's going to change based on temperature so as our temperature goes up our insensible losses are gonna go up in addition when we shortened the airway so if we're in state and say if we put a tracheostomy in we're gonna have more insensible fluid loss because we're losing some surface area of reabsorption and so now if we want to replace fluid how do we do that now in the fluid and energy video go ahead check that out click up there we talked about maintenance fluid requirements and the four to one rule so that's 4 mils per kilo per hour for the first 10 kilos 2 mils per kilo per hour for the second time kilos 1 mil per kilo per hour for every kilo after that you can also take this and go 4 mils per kilo per day if you think about 24-hour period and that would be a hundred mils per kilo for the first 10 50 mils per kilo for the second 10 and then 20 mils per kilo for every kilo after that and so if we wanted to kind of put together these estimates so why does maintenance fluid why does the four to one rule work well let's just take an example and if we take some average numbers here so let's take our urine losses so let's say we have 0.75 mils per kilo that's gonna be 1260 mils if we take our gastrointestinal law says that's going to be 200 add to this sum in sensible losses let's say that's it's hot outside we're in Las Vegas here 12 mils per kilo per day that puts us right about 2300 milliliters and so if you do the 4 to 1 rule for a 70 kilo person that's 24 40s so you can see that it basically will approximate your obligatory fluid losses and this is why this works for determine our maintenance fluid requirement another thing we want to ask ourselves is how about electrolyte losses and so we have some obligatory electrolyte losses and for sodium that's about a hundred to 250 millions per day and for potassium is about 15 to 20 milliequivalents per day then just to throw up here when you're looking at the amount needed of different electrolytes we can say that sodium and we talked about this in the TPN lecture it's about 1 to 2 milli equivalents per kilo per day and then potassium is 0.5 to 1 millions per kilo per day for the other electrolytes while their replacement is important when you're thinking about TPN usually we don't have to think about replacing those but we do want to keep an eye on both sodium and potassium and so what maintenance fluid do you choose we got a few to pick from and I put on a table up here and this is out of Norton's you can review it but it's really important to understand which fluids have how much what electrolytes and I always like to ask the residents medical students oh you wanted to give lactated ringers why don't you want to give that you know so how much sodium is in that and why is that important well it's important because let's say you're in the trauma Bay and you're dealing with the TBI patient and you're gonna give bolus them LR well you don't want to do that because your bulla seing them with fluid that's low in sodium and that may worsen their cerebral edema so you want to stay away from those you know relatively hyponatremic fluids you when you're resuscitating a trauma patient with a TBI so you have to know these fluids and what's in them and I put all the those numbers up here this will also give you some good like knowledge armamentarium so that if you have an NG tube in and we're going to talk about it and you're sucking out gastric fluid what do you replace that with if you have an ostomy and you're dumping out you know small bowel effluent what do you replace that one if you have a patient with a lot of diarrhea what do you replace that with how about a pancreatic fistula what do you replace that with and so we'll go through each of those kind of organ contents but knowing what your fluids are and what their electrolyte compositions are getting give you an idea of what fluid you can replace those losses with another important thing to think about is we think about our maintenance fluid but you also when you're doing perioperative fluid replacement there are other things to take in consideration in our anesthesia College do an awesome job at this but it's important to consider blood loss you also are going to have extra vascular fluid sequestration so in when you're doing an open hernia repair this is going to be low maybe four mils per kilo per hour but when you're doing an AP and open air order it's gonna be double that okay so that that edema is really going to be increasing those bigger operations you also got to think about the drains that you're placing as well as Gi losses so that could be both from nasogastric output or ostomy loss finally up here I just wanted to put in the different volume secreted by the different organs in the GI tract you know the stomach has a great range a thousand of 4,200 milliliters and you can see that if we didn't reabsorb this we would turn into a prune in like hours but fortunately reabsorb we reabsorb most of this content and so that's why our Gi losses are so low in each of these if you look at what is gonna be the best replacement fluid for a particular organ so let's say that we have a nasal gastric tube in and we're sucking out stomach fluid well it's high in sodium and its high in chloride and you're gonna want to replace this with you know normal saline all right now if you take another fluid loss that is much lower in in chloride so let's say you have a pancreatic fistula you know this is going to probably be best replaced with something closer to lactated ringers but you can look at each of these and think about okay this is the loss that I have how do I replace it this could be a good reference for you again out of Norton's all right so I hope that was a good review of the different fluid compartments the different fluids that we utilize in the perioperative period how you give those how much to give and what their electrolyte composition is and now we're going to jump into specific electrolyte disturbances dense topic a lot of information but you can watch this you can review it again I'm also gonna have a review sheet available you can check that out at citizen surgeon comm there's a lot of good resources there totally freely available so check that out if you haven't had a chance to subscribe hit the subscribe button also engage leave some questions and comments what are some topics that you want to hear and then I will totally get back to you so as we close definitely check out the videos on surgical nutrition and definitely subscribe to citizen surgeon YouTube videos you'll know when each of these videos are coming out alright peace out thanks so much for joining us

how do you manage fluid and electrolytes how do you manage hyponatremia what electrolytes are important in this surgery tutorial we&#39;re going to cover all of those questions and everything else about fluid and electrolytes so let&#39;s do it welcome back my name is dr. Eric Pearson and I&#39;m so pumped that you&#39;re joining us for another video I hope that you&#39;ve enjoyed the first few on the metabolic response to injury the surgical nutrition videos if you haven&#39;t actually seen those yet go ahead hit the cards up here if you haven&#39;t had a chance to subscribe go ahead subscribe then you&#39;ll know when all these videos are coming out you know in this Kovan 19 pandemic crisis I figured I loved educating and that this was one of the best ways to scale surgical education I&#39;ve always wanted a resource that I could go to and quickly get some knowledge that I can harness between cases or on the walk in from the car so I&#39;m making these videos 15 and 25 minutes covering the core subjects of surgery so whether you&#39;re a medical student or you&#39;re a resident a fellow a surgeon resetting their board exams I&#39;m hoping getting through these basics is really providing you with a good foundation in general surgery so in this surgery tutorial on fluid and electrolytes we&#39;re gonna cover that chapter that I&#39;m sure you&#39;ve skipped a few times I probably didn&#39;t read it until I was a third-year resident going into the ICU again and I knew that I just had to know all of these values and why they were important so today we&#39;re gonna go over the fluid and electrolyte the obligatory losses and the needs we&#39;re also gonna go through hyper hyponatremia hyper hypokalemia the calcium&#39;s Matic Foss all those really important values so when you get that BMP you&#39;re gonna know how to interpret it you&#39;re gonna have a good reason for getting it and to know what you&#39;re gonna do with the results so without further ado let&#39;s jump into the video for today as always we want to review the question that we ended with and so on part three surgical nutrition if you didn&#39;t see that go ahead hit the card up there part three was on TPN indications in design where we covered all at EPN and how to order it design a basic formula for TPN which is you should know that for your board exams how to at least get started and also for taking care of patients and understanding all those nutritional aspects of the ICU care and even in that post-op care on your patients on the floor so well let&#39;s go to that question so this is a 25 year old 85 kilo male admitted to the surgical ICU with an open abdomen damage control surgery he sustained a solid organ injury of most multiple segments of his small bowel mesentery required resection he&#39;s now in multiple discontinuity and what I asked was to write up a basic TPN solution for this patient and what are some of the major considerations of his ongoing TPN needs all right so to answer this question definitely check out that video we&#39;re not gonna go to all the numbers here but the first thing I wanted you to think about is is this guy have a good indication for TPM well yeah Valon discontinuity you know he&#39;s gonna be NPO for at least five to seven days we knew that he was pretty basically healthy but still he&#39;s gonna definitely hit that threshold for needing parenteral nutrition secondly think in terms of fluid in energy so when we&#39;re designing TPN we think of fluid first so in this guy we&#39;re gonna do the four to one rule that&#39;s gonna give us our fluid needs I&#39;ll let you calculate on your own okay and then when we go in the energy we&#39;re gonna say okay critically injured guy we&#39;re getting probably previously healthy 30 kilocalories and then once we determine that total caloric need we&#39;re gonna need to give about 60% of carbohydrates and we&#39;ll do that by calculating our percentage d&#39;être dextrose solution we want to give 30% lipid we&#39;re gonna want to increase the amount of those omega-3 of those anti-inflammatory fatty acids and the lipid component and then when we go to the protein we&#39;re gonna want to be about 1 to 1.5 grams per kilo now when you do all those calculations you&#39;ll have a good simple design of your TPM to that we&#39;re gonna maybe add some daily vitamins we&#39;re gonna want to add your micronutrients we might want to add an inch to antagonist might want to add some insulin if he&#39;s had hyperglycemia and then we&#39;re gonna want to have a really good understanding of how we follow this going forward and that gets to the second question so what are the major considerations one major consideration is sky as an open admin he&#39;s in discontinuity he has a vac that&#39;s gonna be draining fluid he has probably needs a gastric tube which is draining fluid so we&#39;re gonna want to really closely monitor what his blood pressure heart rate urine output are and how his you know overall fluid status is to determine those fluid needs you know secondly is as we get further along in the ICU course we&#39;re gonna probably want to do some indirect calorimetry we&#39;re gonna want to calculate as RQ find out are we over/under feeding it is he gonna need more calories per kilo is he going to be in one of those critically injured patients that&#39;s up at 35 or 40 Killick house grand per day and we&#39;re not going to know that unless we do in our queue so if you need to go back to that video again go ahead hit that card you get back up into the fluid and energy we talked about how to calculate the RQ what it means why when you burn glucose it&#39;s a RQ equals one and while you burn the fat like palmitate the RQ is 0.7 so if you go watch that video you&#39;ll totally crush it and now let&#39;s get on to the TOC fluid and electrolytes let&#39;s do it all right so fluid and electrolytes this is what I like to refer to as the basics of the basics this is something that you do in every single patient every single day so you gotta know what&#39;s going on with fluid and electrolytes so first we&#39;re gonna talk about the body&#39;s fluid in its compartments second you&#39;re gonna be confident in understanding all of the electrolyte disturbances hyponatremia hypernatremia hypokalemia hyperkalemia hypocalcemia hypercalcemia we&#39;re gonna go through magnum phosphate will acid-base we&#39;re gonna get it all in and third is you&#39;re gonna want to know how to fix these electrolyte disturbances and we&#39;re going to focus on a couple you know sodium is one of those really difficult ones where you have hyperosmolar or hyperbole or hypo and hyper nutri mia and we&#39;re gonna get through all that so I hope you&#39;ve joined with me the whole time and towards the end we&#39;re gonna put it all together and I think you&#39;re really gonna get a lot out of this video all right like every video we like to ask why so why is important to learn this it&#39;s important to learn this because it&#39;s something we do every day you can&#39;t just click that d5 half an S with 28 K it&#39;s 75 milliliters per hour and just hope it&#39;s gonna work you got to know that when you get that BMP and all of a sudden the sodium is 125 where the sodium is 117 and that elderly patient who had a fall and came in with the TBI how are you gonna replace that how are you gonna fix it you know when you have that patient who comes in with a potassium of 6 what does that mean how are you gonna fix that when you have the patient who&#39;s hi pal Kelsey make what does that mean hypomagnesemia or low phosphate what does that mean how are you gonna fix it so understanding the fluid compartments the body and the fluid that you give how that&#39;s distributed as well as the electrolytes or something as surgeons that we need to know how to do every day you can&#39;t just look and hope that the number turns red in epic or whatever a lot of electronic health record you use you got to know the numbers you got to know the why all right so let&#39;s go for the references the major reference for today is Norton&#39;s surgery I think that for the basic chapters Norton&#39;s is probably the best reference so if you&#39;re going to get a textbook and you&#39;re going to use it as a reference to study the basic science of these core surgical medical knowledge topics I think Norton&#39;s is the way to go when we get into the clinical topics I&#39;ll be referring to sabatons I&#39;ll be referring to top knife I&#39;ll be referring to a few of the other textbooks and reference books things the ones that I love and but for this one go back to Norton&#39;s these chapters they&#39;re dense but they really have what you need to know to be confident in understanding these basic building blocks of surgery all right to kick it off we&#39;re gonna look at the compartments of the body now this is important why is it important it&#39;s important because as we&#39;ll talk about the fluid that you give whether it&#39;s d5 water or normal saline or 5% albumin or blood that fluid that we give distributes to different compartments and so if you don&#39;t know what compart the compartments are what percentage they are in the body and where that fluid goes you&#39;re not going to know what to do in what situation so you have that patient comes in with one liter blood loss right how do you replace one liter and how much volume do you have to give all right well you&#39;re gonna know in 10 minutes from now you&#39;re gonna know that answer okay so when we look at total body water it can change with age and it can also change or gender but look at it is about 60 percent of total body weight is water now that changes a little bit so when we look at newborn so I take care of newborns as a pediatric surgeon and about 75 to 80 percent of their body weight is water and this decreases with age once you get to one-year-old it&#39;s about 65 percent of weight is totally bonded water and then once you get up to adulthood or late adolescence it&#39;s 60 percent of total body weight is water for males and then about 50 percent for females when we take that sixty percent that sixty percent of total body water is divided into two basic compartments you have your intracellular which is the majority that&#39;s gonna be 40 of the 60 okay and then you have the extracellular which is 20% and so those two together make up total body water forty percent for intracellular 20% for extracellular and each of those compartments have different electrolyte distributions when we look at the intracellular component so that&#39;s the majority the major cation is potassium now this is the opposite when you get to the extracellular compartment which makes up that 20% and that&#39;s where the major extracellular cation is sodium and the potassium level is very low and you can see that right here now when we divide the extracellular compartment up we get into the plasma volume which is five percent of that total twenty and then you get into the interstitial volume and that&#39;s 15 percent in the constituent acheived of each of those that&#39;s important is not so much an electrolyte but it&#39;s albumin so in the plasma where we measure albumin we know that it&#39;s concentration is about four milligrams per deciliter when we look at the interstitial volume we know that it&#39;s much less than that it&#39;s about one milligram per deciliter all right so those are the those are the percentages so total body water sixty percent that sixty is broken down and a 40 percent intracellular 20 percent extracellular that exercise is broken down into 15 percent interstitial five percent different fluids have a different volume of distribution so when you give a particular fluid it is going to spread out into a particular volume okay now let&#39;s take total body water so that&#39;s 60% of our total weight what fluid distributes across that entire space so that&#39;s d5 water so if you give d5 water that&#39;s going to distribute over the total body water compartment and so let&#39;s take the next volume so that would be our extracellular volume that&#39;s 20% of our total body weight and what fluid distributes over that and so that&#39;s gonna be normal saline so normal saline is isotonic to our extracellular volume so it&#39;s going to distribute over that compartment and lastly let&#39;s take our plasma volume so what&#39;s going to distribute over our plasma volume so that&#39;s going to be 5% albumin so when you give 5% albumin instead of distributing over all of total body water it&#39;s gonna stay within our plasma volume or 5% of our total body weight and this is going to give you an idea we&#39;re gonna do a clinical scenario where when a patient comes in with blood loss and you choose a particular fluid to give that patient how much fluid are you gonna have to give to replace that blood loss so let&#39;s get into that so let&#39;s say that you have a 60 year old male large volume hematemesis in a history of esophageal varices you&#39;re estimating that he&#39;s lost about a liter of blood as he&#39;s in stage 2 shock so to replace this blood loss how much D 5 water would you have to give versus normal saline versus 5% albumin so put the pause button on go ahead see if you can calculate this out and think about how much of each of these fluids they&#39;re gonna need to replace that one liter of blood okay so in order to find out the volume that you have to give we can do a pretty simple calculation so that&#39;s the volume and fuse is equal to the expected compartment increment divided by the normal compartment volume multiplied by the volume of distribution for that particular fluid and so we can go through this for each of them and then you&#39;ll have a really good idea of how this works with the flue that you&#39;re giving in the resuscitation Bay so how about for d5w so our expected compartment volume increment is one liter we lost the liter of blood and we want to give a liter okay so we want that to increase by a leader we divide that by the normal compartment volume so the normal compartment volume of plasma is five percent of seventy kilo so that&#39;s going to be 3.5 liters so that&#39;s 3.5 then you multiply that by the volume and distribution of that fluid or 42 liters so if you want to replace this 1 liter of blood with d5w you&#39;re gonna have to give 12 liters then you don&#39;t want to do that why do you not want to do that it&#39;s gonna spread over the whole total body water compartment and so you&#39;re gonna put a ton in the interstitial volume and your that person&#39;s gonna be the Michelin Man all right so let&#39;s go to the next one how about normal saline so let&#39;s go to the next one how about normal saline when we do normal saline our expected volume increment is again 1 we divide this by the normal compartment volume so 3.5 again five percent of 70 kilos we multiply that by the volume of distribution for normal saline which is the extracellular volume so that&#39;s 14 liters and we get 4 liters so that means if you want a one liter increase in your plasma volume your blood volume you&#39;re going to want to have to give 4 liters of normal saline and so you can say well where does that additional three liters go that it&#39;s gonna go to the interstitial fluid okay and that&#39;s why all those wrinkles go away when you resuscitate somebody with a ton of normal saline all right so now let&#39;s look at colloid so if we take 5 percent human what&#39;s gonna happen so you get one liter divided by 3.5 liters which is our compartment volume again you multiply that by the volume of distribution for albumin 5% and what do you get you get one liter alright so now there&#39;s a whole discussion about what&#39;s better for trauma resuscitation colloids versus crystalloids we&#39;re not going to get that into that right now we&#39;ll get into that and maybe another talk but for your understanding this is how you can determine what volume you need to infuse of what fluid and where that fluid is gonna go I&#39;m gonna pop over here for a second and now we can talk about what our obligatory fluid losses so if you don&#39;t do anything how much fluid II just gonna lose and how much fluid you&#39;re gonna have to replace so this is your daily need of fluid and electrolytes so first you gotta make urine no no matter what you&#39;re still gonna pee and your normal you&#39;re in production is gonna be about a half a mil per kilo per hour to a mil four kilo per hour now if we look at our GI losses and we&#39;ll go into each of these organs and how much fluid they&#39;re actually producing but the majority of gastrointestinal secretions are reabsorbed and so you&#39;re really only losing about 100 to 200 milliliters of fluid for our gi losses and then we have our n sensible losses and so that&#39;s 8 to 12 mils per kilo per day and this is gonna change so it&#39;s going to change based on temperature so as our temperature goes up our insensible losses are gonna go up in addition when we shortened the airway so if we&#39;re in state and say if we put a tracheostomy in we&#39;re gonna have more insensible fluid loss because we&#39;re losing some surface area of reabsorption and so now if we want to replace fluid how do we do that now in the fluid and energy video go ahead check that out click up there we talked about maintenance fluid requirements and the four to one rule so that&#39;s 4 mils per kilo per hour for the first 10 kilos 2 mils per kilo per hour for the second time kilos 1 mil per kilo per hour for every kilo after that you can also take this and go 4 mils per kilo per day if you think about 24-hour period and that would be a hundred mils per kilo for the first 10 50 mils per kilo for the second 10 and then 20 mils per kilo for every kilo after that and so if we wanted to kind of put together these estimates so why does maintenance fluid why does the four to one rule work well let&#39;s just take an example and if we take some average numbers here so let&#39;s take our urine losses so let&#39;s say we have 0.75 mils per kilo that&#39;s gonna be 1260 mils if we take our gastrointestinal law says that&#39;s going to be 200 add to this sum in sensible losses let&#39;s say that&#39;s it&#39;s hot outside we&#39;re in Las Vegas here 12 mils per kilo per day that puts us right about 2300 milliliters and so if you do the 4 to 1 rule for a 70 kilo person that&#39;s 24 40s so you can see that it basically will approximate your obligatory fluid losses and this is why this works for determine our maintenance fluid requirement another thing we want to ask ourselves is how about electrolyte losses and so we have some obligatory electrolyte losses and for sodium that&#39;s about a hundred to 250 millions per day and for potassium is about 15 to 20 milliequivalents per day then just to throw up here when you&#39;re looking at the amount needed of different electrolytes we can say that sodium and we talked about this in the TPN lecture it&#39;s about 1 to 2 milli equivalents per kilo per day and then potassium is 0.5 to 1 millions per kilo per day for the other electrolytes while their replacement is important when you&#39;re thinking about TPN usually we don&#39;t have to think about replacing those but we do want to keep an eye on both sodium and potassium and so what maintenance fluid do you choose we got a few to pick from and I put on a table up here and this is out of Norton&#39;s you can review it but it&#39;s really important to understand which fluids have how much what electrolytes and I always like to ask the residents medical students oh you wanted to give lactated ringers why don&#39;t you want to give that you know so how much sodium is in that and why is that important well it&#39;s important because let&#39;s say you&#39;re in the trauma Bay and you&#39;re dealing with the TBI patient and you&#39;re gonna give bolus them LR well you don&#39;t want to do that because your bulla seing them with fluid that&#39;s low in sodium and that may worsen their cerebral edema so you want to stay away from those you know relatively hyponatremic fluids you when you&#39;re resuscitating a trauma patient with a TBI so you have to know these fluids and what&#39;s in them and I put all the those numbers up here this will also give you some good like knowledge armamentarium so that if you have an NG tube in and we&#39;re going to talk about it and you&#39;re sucking out gastric fluid what do you replace that with if you have an ostomy and you&#39;re dumping out you know small bowel effluent what do you replace that one if you have a patient with a lot of diarrhea what do you replace that with how about a pancreatic fistula what do you replace that with and so we&#39;ll go through each of those kind of organ contents but knowing what your fluids are and what their electrolyte compositions are getting give you an idea of what fluid you can replace those losses with another important thing to think about is we think about our maintenance fluid but you also when you&#39;re doing perioperative fluid replacement there are other things to take in consideration in our anesthesia College do an awesome job at this but it&#39;s important to consider blood loss you also are going to have extra vascular fluid sequestration so in when you&#39;re doing an open hernia repair this is going to be low maybe four mils per kilo per hour but when you&#39;re doing an AP and open air order it&#39;s gonna be double that okay so that that edema is really going to be increasing those bigger operations you also got to think about the drains that you&#39;re placing as well as Gi losses so that could be both from nasogastric output or ostomy loss finally up here I just wanted to put in the different volume secreted by the different organs in the GI tract you know the stomach has a great range a thousand of 4,200 milliliters and you can see that if we didn&#39;t reabsorb this we would turn into a prune in like hours but fortunately reabsorb we reabsorb most of this content and so that&#39;s why our Gi losses are so low in each of these if you look at what is gonna be the best replacement fluid for a particular organ so let&#39;s say that we have a nasal gastric tube in and we&#39;re sucking out stomach fluid well it&#39;s high in sodium and its high in chloride and you&#39;re gonna want to replace this with you know normal saline all right now if you take another fluid loss that is much lower in in chloride so let&#39;s say you have a pancreatic fistula you know this is going to probably be best replaced with something closer to lactated ringers but you can look at each of these and think about okay this is the loss that I have how do I replace it this could be a good reference for you again out of Norton&#39;s all right so I hope that was a good review of the different fluid compartments the different fluids that we utilize in the perioperative period how you give those how much to give and what their electrolyte composition is and now we&#39;re going to jump into specific electrolyte disturbances dense topic a lot of information but you can watch this you can review it again I&#39;m also gonna have a review sheet available you can check that out at citizen surgeon comm there&#39;s a lot of good resources there totally freely available so check that out if you haven&#39;t had a chance to subscribe hit the subscribe button also engage leave some questions and comments what are some topics that you want to hear and then I will totally get back to you so as we close definitely check out the videos on surgical nutrition and definitely subscribe to citizen surgeon YouTube videos you&#39;ll know when each of these videos are coming out alright peace out thanks so much for joining us

Transcript for:Fluid and Electrolyte Management in Surgery

Transcript for:
Fluid and Electrolyte Management in Surgery