Latest / Banter At The Bedside / IV Fluids Explained, Part 1: Starling Forces, CVP & Maintenance Fluids

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IV Fluids Explained, Part 1: Starling Forces, CVP & Maintenance Fluids · Banter At The Bedside

0:00
SPEAKER_01: Not for not for these two girls.
0:02
SPEAKER_01: No.
0:03
SPEAKER_01: I needed a trigger warning.
0:04
SPEAKER_01: We need a trigger warning for this episode.
0:06
SPEAKER_01: I will put a trigger warning in.
0:08
SPEAKER_02: Dog deaths will be talked about.
0:17
SPEAKER_01: Hey everybody, this is Kaylee.
0:19
SPEAKER_01: Welcome back to Banter at the Bedside.
0:21
SPEAKER_01: We're back again with Dr.
0:22
SPEAKER_01: Michael for another one of our educational episodes.
0:25
SPEAKER_01: Before we get started, we're going to go through our disclaimers.
0:28
SPEAKER_01: This is for entertainment purposes only.
0:30
SPEAKER_01: This is not medical advice.
0:33
SPEAKER_01: If you have any questions, you should seek the care of your own medical provider.
0:36
SPEAKER_01: We are not being compensated in any way.
0:39
SPEAKER_01: These are our opinions.
0:40
SPEAKER_01: We do not represent any entity or organization.
0:43
SPEAKER_01: And we are filming from the comfort of our own homes off the clock.
0:48
SPEAKER_01: Now that that's out of the way, I'm sure you guys, if you're coming back, as you know, I'm Kaylee.
0:54
SPEAKER_01: I am a nurse of 18 years, and we have our other main co-host, Abby.
0:59
SPEAKER_01: Hey guys.
0:59
SPEAKER_01: She is an APP.
1:01
SPEAKER_01: She has worked in ICU for eight years, but she's been in healthcare for over 17.
1:05
SPEAKER_01: And we have Dr.
1:06
SPEAKER_01: Michael back again.
1:07
SPEAKER_01: He is a physician of 17 years, 10 of those as an intensivist.
1:12
SPEAKER_05: Thank you.
1:13
SPEAKER_05: Thank you for having me.
1:14
SPEAKER_05: Excited to be back.
1:15
SPEAKER_01: So today we have a divisive topic, a hot topic, a highly debated topic.
1:20
SPEAKER_01: Fluids.
1:22
SPEAKER_01: Fluids, Ivy fluids, guys.
1:23
SPEAKER_01: We're going to do it.
1:24
SPEAKER_01: This is a hard-hitting one.
1:25
SPEAKER_01: And we have Dr.
1:26
SPEAKER_01: Michael to tell us all about what you should give, why you should give, or what maybe what you shouldn't give.
1:32
SPEAKER_01: So I'm going to turn it over to him.
1:35
SPEAKER_05: Okay.
1:35
SPEAKER_05: I uh I'll see if I can do this justice.
1:38
SPEAKER_05: Uh, it's something that I I am passionate about, and I feel like people learned things a certain way and like really stick with it.
1:47
SPEAKER_05: So I can get not frustrated, but it is like you hear these things that just get perpetuated over and over again, like, oh, we have to do this or we have to do that.
1:55
SPEAKER_05: Uh, but the more I looked into fluids, it is it's more complicated than you think.
2:02
SPEAKER_05: So hopefully I can take you on this.
2:06
SPEAKER_05: That's not going to be too much in the weeds on stuff.
2:09
SPEAKER_05: We're going to first start out with just fluids in the body, because I want you to get an idea of like how fluids work before we can get into like what kind of fluids to give or how you want to do with it.
2:22
SPEAKER_05: And so the first thing is just how much fluid is in our body.
2:26
SPEAKER_05: And on average, it's about 42 liters of water.
2:33
SPEAKER_05: So if you think about that, and then you're gonna put if you drink water.
2:38
SPEAKER_05: Sure, if you drink water.
2:42
SPEAKER_05: Oh boy.
2:45
SPEAKER_05: Two two-thirds of that is going to be intracellular, which we don't like do a whole lot with, which gives us about one-third extracellular.
2:57
SPEAKER_05: So 14 liters, if you want to do the math on that.
3:01
SPEAKER_05: You take that, 14 liters, and around a quarter of it is intravascular, and the rest of it is interstitial.
3:12
SPEAKER_05: So you're looking at three to four liters being intravascular, and then the other 10, 11 liters being interstitial.
3:20
SPEAKER_05: So if you really look at it and you're looking at just our circulatory system, you can say on average, let's say four liters of blood, like as you go with it on the thing.
3:33
SPEAKER_05: It's if you, you know, it's going to be talking about plasma and stuff.
3:37
SPEAKER_05: That's not that much.
3:38
SPEAKER_05: You know, uh, how many of us have given four, five, six liters of fluid to somebody?
3:43
SPEAKER_05: I mean, you're basically doubling their entire intervascular volume if you give it over a certain amount of time, with obviously a lot uh going into the interstitial space.
3:53
SPEAKER_05: So that's the first part that I wanted to talk about with it.
3:58
SPEAKER_05: The next thing I wanted to talk about is just kind of how that fluid stays in the intervascular part.
4:06
SPEAKER_05: And then I also wanted to talk about like how it moves so that everyone's just like on the same page.
4:12
SPEAKER_05: So the first thing I'll talk about is how it stays in the intervassular versus the interstitial.
4:20
SPEAKER_05: Everyone knows about the Starlin curve where it talks about like if you give volume, it stretches and it increases cardiac output, and you have that curve that you learn about.
4:30
SPEAKER_05: But there's also a Starlin equation, and it is a much more long in-depth equation that has like cofactors and things and stuff that a lot of like letters that represent numbers.
4:44
SPEAKER_05: But the overall issue of it is the two main forces that keep stuff either in your intervascular space or pushes things out of your intervascular space is your oncotic pressure and your hydrostatic pressure.
4:59
SPEAKER_05: So if your your hydrostatic pressure is just that constant pressure, if you think about someone that is heart failure and their their whole just vascular system, super volume overloaded and just pushing against the sidewalls.
5:12
SPEAKER_05: If you push against the sidewalls, it'll just like leak out and leak out into the interstitium.
5:18
SPEAKER_05: That's your hydrostatic pressure.
5:19
SPEAKER_05: That's the pressure that wants to push that plasma, that fluid out into the interstitium.
5:24
SPEAKER_05: And then the opposite is your oncotic pressure.
5:27
SPEAKER_05: Your oncotic pressure wants to pull that interstitial fluid back into the intravascular space.
5:33
SPEAKER_05: And your oncotic pressure is mainly like your proteins.
5:37
SPEAKER_05: And so it depends on how high your hydrostatic pressure is and what your oncotic pressure is on whether or not fluid will stay intravascular.
5:47
SPEAKER_05: So I already gave the example of someone that's like in heart failure.
5:50
SPEAKER_05: They have a lot of hydrostatic pressure, so they end up with getting a lot of fluid that pushes out, they end up with lower extremity edema.
5:58
SPEAKER_05: The other side of the coin with that is low oncotic pressure.
6:02
SPEAKER_05: So you think about like a cirrhotic who has just like a low albumin, they can't keep the fluid intravascular because they don't have the proteins to draw it in.
6:12
SPEAKER_05: And so they also third space fluids, but they third space it in different areas.
6:17
SPEAKER_05: So if you're a cirrhotic, you end up with ocides, versus if you're have increased hydrostatic pressure, you're more likely to have like pulmonary edema and things, those sort of things.
6:28
SPEAKER_05: The different organs have different sensitivities to hydrostatic pressure.
6:34
SPEAKER_05: So the most sensitive organ to hydrostatic pressure is your lung.
6:38
SPEAKER_05: And that's why whenever you're you have a person that has heart failure, the most common symptom is going to be like shortness of breath, gonna be pulmonary edema, because as soon as you start getting that increased hydrostatic pressure, it's gonna push the fluid out of the vasculature into the lungs.
6:54
SPEAKER_05: You can manipulate how you get fluid in the body by kind of manipulating things.
7:00
SPEAKER_05: If you can lower hydrostatic pressure, if you could increase oncotic pressure, then you're more likely to keep fluid intravascular.
7:07
SPEAKER_05: And so we see this all the time when we do like a paracyntesis.
7:11
SPEAKER_05: When we do a large volume paracentesis, we worry about that fluid shift because all that intravascular volume is just going to start leaking out.
7:17
SPEAKER_05: And so we give albumin to keep that fluid intravascular so you don't have those large fluid shifts.
7:23
SPEAKER_05: And that's because you have to have that oncotic pressure to keep it in.
7:28
SPEAKER_05: Um to go down like a nerdier pathway for that oncotic pressure.
7:34
SPEAKER_05: Um there the question is like, is there an oncotic pressure that is like a breaking point, right?
7:44
SPEAKER_05: That's like you have to have X amount of oncotic pressure.
7:47
SPEAKER_05: Um and the answer is there's something called the Gibbs Donin effect.
7:52
SPEAKER_01: Um we got another another dual name effect.
7:57
SPEAKER_05: Another Gibbs don't gib Gibbs donan.
8:02
SPEAKER_05: The Gibbs donan effect talks about oncotic pressure.
8:07
SPEAKER_05: So 75% of your oncotic pressure is due to albumin.
8:10
SPEAKER_05: It's one of the main proteins that's like in our blood.
8:14
SPEAKER_05: And albumin's negatively charged.
8:17
SPEAKER_05: And so because it's negatively charged, it actually draws other, like positively charged things to it.
8:25
SPEAKER_05: So calcium attaches to it, and sodium and potassium and these and these positively charged ions and attach to it, and it makes the molecule bigger than what it actually is.
8:36
SPEAKER_05: So if you did your study and you said on X amount of pr of albumin, how much should it like affect the pull of fluid into the intravascular space?
8:47
SPEAKER_05: Whatever you think it is, it actually ends up being more than that.
8:51
SPEAKER_05: So it it and that is the Gibbs Donin effect.
8:54
SPEAKER_05: It has a stronger pull because the molecule is bigger than what you think it is because it wants to attach on those cations and then just make the molecule bigger.
9:06
SPEAKER_02: Is that a lot of basic chemistry?
9:09
SPEAKER_05: So yeah, a lot of like positives and negatives.
9:12
SPEAKER_05: And at a certain point, you lose that benefit.
9:15
SPEAKER_05: So once you drop below a certain albumin level, you just don't get that benefit as much with it.
9:22
SPEAKER_05: And it's around 2 to 2.5, uh, probably closer to 2, but ish on there.
9:28
SPEAKER_05: And so it's anybody.
9:31
SPEAKER_05: Yeah.
9:32
SPEAKER_01: Like the lab we draw?
9:33
SPEAKER_05: Yes.
9:34
SPEAKER_05: Yeah.
9:34
SPEAKER_05: So if you look and you have an albumin level on your like a paddock panel and it says that it's 3.1, you're still getting that effect.
9:44
SPEAKER_05: Like a normal is going to be around four.
9:46
SPEAKER_05: It's not quite normal, but you still have that effect.
9:49
SPEAKER_05: Once you get down to like two less than two, 1.8, you're losing, not only are you losing all that oncotic pressure, but you're also losing that benefit of that Gibbs donut effect.
10:00
SPEAKER_05: So it's even more of a profound drop.
10:04
SPEAKER_05: So you're just going to be third spacing a lot of your fluid.
10:08
SPEAKER_05: So if you ever tried to resuscitate somebody, fluid resuscitate somebody with an albumin of 1.8, it is unbelievably hard to do because you just put it in and it just goes right back out into the interstitium.
10:23
SPEAKER_01: Yeah.
10:24
SPEAKER_01: That makes sense.
10:25
SPEAKER_01: It sucks.
10:27
SPEAKER_05: So you that is a uh thing we can talk about later to say, like, hey, in resuscitation, is there an argument for albumin?
10:37
SPEAKER_05: There is an argument for oncotic pressure that I'll kind of go in as we kind of go down this way of doing things with it.
10:43
SPEAKER_05: Now, the other thing that you think would be in there is osmotic pressure.
10:48
SPEAKER_05: And your osmolarity, or talking about just all the different uh like sodium and chloride and anything in your blood that would be like your like your electrolytes and things, you can affect the osmolarity.
11:04
SPEAKER_05: And osmolarity is not in the Starling equation because it can pass so freely from the intravascular space to the interstitial space that it doesn't, it it reaches equilibrium so quickly that it is not included in that equation in regular everyday life.
11:23
SPEAKER_05: You can change it in the hospital.
11:26
SPEAKER_05: And we do it all the time, right?
11:28
SPEAKER_05: If someone is in the neuroICU and you think they have intracranial hypertension, we give them hypertonic saline, and that increase in osmolarity pulls fluid from the interstitial space into the intrabascular space to lower your intracranial pressure.
11:43
SPEAKER_05: So, yes, it is included into ways to manipulate fluid.
11:50
SPEAKER_05: Uh, we it's just not included in that equation, but we can do it like in the hospital.
11:56
SPEAKER_05: And so that anytime you're looking at fluids, it's important to understand.
12:02
SPEAKER_05: Is there, are you trying to get intravascular fluid?
12:06
SPEAKER_05: Are you trying to get like overall extracellular fluid?
12:09
SPEAKER_05: Are you trying to get overall total body fluid?
12:12
SPEAKER_05: What are you trying to replace?
12:14
SPEAKER_05: And it it does make a difference.
12:17
SPEAKER_05: Like if you're in hypovolemic shock, then your overall volume down, like your total body volume is down.
12:23
SPEAKER_05: And so you're just replacing volume.
12:26
SPEAKER_05: If you can just replace the volume that was lost, you're good.
12:29
SPEAKER_05: If you're in like distributive shock and you're vasodilated and you have a lot of cytokines, especially like septic shock, you it's not like at 8 a.m.
12:40
SPEAKER_05: you were like you could be eating breakfast completely normal, you volemic.
12:45
SPEAKER_05: You're in septic shock at 4 p.m.
12:47
SPEAKER_05: You didn't lose four liters of fluid between breakfast and the afternoon.
12:52
SPEAKER_05: You third spaced a lot of fluid and you vasodilated.
12:55
SPEAKER_05: So you're you're hypotensive because you've lost intravascular volume.
13:00
SPEAKER_05: So you still have that volume in your body for the most part.
13:04
SPEAKER_05: It's just not where you want it to be.
13:06
SPEAKER_05: And so you're focusing more on your intravascular resuscitation if possible.
13:13
SPEAKER_05: And so it can be a little bit different.
13:15
SPEAKER_05: Uh, so it's something we'll kind of go to when we're talking about like the resuscitation types of things with it.
13:20
SPEAKER_05: But you can you can look at not just saying, like, okay, I'm gonna replace volume, but you're saying, like, uh, do I need to replace oncotic pressure?
13:30
SPEAKER_05: Do I need to add osmolarity to help pull things in?
13:34
SPEAKER_05: Uh, the other thing to consider is if you give enough oncotic pressure and you are you're like, well, if if getting it above two and a half is good, let's just bring it all the way to four.
13:45
SPEAKER_05: Uh, if you keep giving enough oncotic pressure, you'll drastically increase hydrostatic pressure just because it'll bring so much volume in, then it'll start like causing that hydrostatic pressure that pushes against it.
13:57
SPEAKER_05: And so you could have somebody that's like just cirrhotic and has a side ease, you give them a whole bunch of oncotic pressure, you can give them pulmonary edema that they didn't have before because you just bring so much in so quickly that their lack of their lack of oncotic pressure now becomes an increase in hydrostatic pressure after you you give if you give too much.
14:20
SPEAKER_05: So I never try to like normalize uh oncotic pressure, but I do try to get it above two and a half, like for me.
14:28
SPEAKER_05: And I'll and I'll kind of go into it a little bit later and stuff.
14:31
SPEAKER_05: Now, the next thing to get into is how do you get fluid around the body, like the whole like pump side of things with it.
14:41
SPEAKER_05: And I think that's important because you're it it'll help you realize like your goals.
14:46
SPEAKER_05: And so if you ever think about it, like what determines that your venous blood returns to your right atrium?
14:55
SPEAKER_05: Uh, it actually has to, I mean, we're standing up a often, some of us less than others, but overall we're still pumping blood against gravity back to our heart in order to keep blood pumping.
15:08
SPEAKER_05: And it actually has very little to do with what our arterial pressure is.
15:15
SPEAKER_05: And so there's there's this whole idea that as your arteries become your arterioles, become your capillaries, you just lose a lot of that pressure because of how it just kind of expands, expands, expands.
15:29
SPEAKER_05: And so it doesn't really contribute to the pressure gradient that gets your blood back to your heart.
15:36
SPEAKER_05: So whenever we're talking about fluids, we kind of have to understand what we're doing.
15:40
SPEAKER_05: We're we're giving fluids because we're saying we're not pumping enough blood around our body to deliver oxygen.
15:48
SPEAKER_05: So we're not getting that cardiac output.
15:50
SPEAKER_05: We need that fluid, that volume, to be able to increase our cardiac output, which in turn delivers oxygen for oxygen delivery.
15:59
SPEAKER_05: That is very much reliant on our venous return or our ability to push blood from our periphery back to our right atrium.
16:10
SPEAKER_05: And the the way that we do it is through a pressure gradient.
16:13
SPEAKER_05: It goes from higher pressure to lower pressure.
16:15
SPEAKER_05: And that pressure gradient has nothing to do with the arterial side.
16:19
SPEAKER_05: It is it is your vinual pressure, which is the veins immediately after your capillaries, so the tiny vinues, minus our right atrial pressure.
16:29
SPEAKER_05: That's our gradient.
16:31
SPEAKER_01: I ain't heard the word vinule.
16:32
SPEAKER_01: I mean it.
16:35
SPEAKER_01: Two decades.
16:36
SPEAKER_05: So venue.
16:39
SPEAKER_05: It's super, super important.
16:41
SPEAKER_05: Um, obviously.
16:47
SPEAKER_03: I have not heard it in so long.
16:49
SPEAKER_03: I will say this was like, I do remember in NP school knowing this fact for whatever reason, like knowing that we moved from high pressure to low pressure was so impressive to one of my preceptors.
17:06
SPEAKER_03: Like, I said it to him uh about a PE, and I was like, well, it's because we move from a high pressure gradient to a low pressure gradient.
17:14
SPEAKER_03: Like that's how the body works.
17:15
SPEAKER_03: It uses physics.
17:16
SPEAKER_03: And he was like, Wait, you know that?
17:19
SPEAKER_03: And I was like, I do.
17:22
SPEAKER_03: So it's I don't I don't know.
17:24
SPEAKER_03: I guess maybe a lot of people don't remember it, but remember this fact.
17:29
SPEAKER_05: It just keeps being helpful.
17:31
SPEAKER_05: Yeah.
17:31
SPEAKER_05: It does.
17:32
SPEAKER_05: Um if you look at like a starling curve, there they usually overlay it with a guyton Venus return curve.
17:45
SPEAKER_01: Oh Lord, that's lots of curves.
17:47
SPEAKER_01: I feel like I should be taking that curve college over here.
17:51
SPEAKER_05: Well, once you hear what Gyton did, you may not want to write it down.
17:55
SPEAKER_05: But um Well, I wasn't going to He so there's he wanted to know what the mean circulatory filling pressure pressure was.
18:08
SPEAKER_05: So what is the idea was if your heart stopped, your vascular system would reach a steady state.
18:16
SPEAKER_05: It would all be the same pressure, right?
18:18
SPEAKER_05: The only reason we have differences in pressure across our system is because our heart is pumping.
18:22
SPEAKER_05: So if you stop the pump, it will reach just like a resting pressure.
18:27
SPEAKER_05: So we put a bunch of catheters in a dog or multiple dogs, and then he just killed the dogs.
18:34
SPEAKER_05: And then he stopped their hearts, and then he measured what the pressure was in like the arteries and the vinules and the veins and like all across the body to say what is the resting pressure of the circulatory system.
18:51
SPEAKER_02: Or dog.
18:53
SPEAKER_05: Yeah, that's why I said baby.
18:54
SPEAKER_05: Don't like I gave you, I feel like I gave like a warning on there.
18:58
SPEAKER_01: No, that was not appropriate.
19:00
SPEAKER_01: Not for not for these two girls.
19:02
SPEAKER_01: No.
19:03
SPEAKER_01: Um, so yeah, so we needed a trigger warning.
19:05
SPEAKER_01: We need a trigger warning for this episode.
19:06
SPEAKER_02: I will put a trigger warning in dog desk will be talked about.
19:12
SPEAKER_05: So in this, he determined that the the pressure was around eight to twelve millimeters of mercury.
19:22
SPEAKER_05: And we now use that value for what we call our mean systemic filling pressure.
19:29
SPEAKER_05: Our venual pressure is somewhere around there.
19:33
SPEAKER_05: You could say eight to twelve, some people say like 10 to 15, somewhere in that that area.
19:40
SPEAKER_05: The reason that's so important is we have so many venules, right?
19:44
SPEAKER_05: Because as your as your artery becomes your arterioles and starts getting broader and broader, like web network, is there's just millions of them.
19:52
SPEAKER_05: If you add a bunch of volume to the person, their venules uh can stretch very easily.
19:59
SPEAKER_05: And they don't change their pressure that much with fluid just because it's spread out over such a large area.
20:08
SPEAKER_05: Your right atrium is a much like sturdier tissue.
20:13
SPEAKER_05: It can't stretch infinitely based on fluid, so it will actually start raising its pressure.
20:19
SPEAKER_05: So if you give somebody four, five, six liters of fluid, your right atrium pressure will go up at a higher rate than your venual pressure.
20:28
SPEAKER_05: So a normal right atrial pressure, everyday life is like zero to five.
20:34
SPEAKER_05: Um, a normal venual pressure is you can use eight to twelve or ten to fifteen, whatever you want to use, but that gives you a gradient, right?
20:42
SPEAKER_05: Like let's say your venual pressure is 12 and your right atrial pressure is three, you now have that nine gradient that's going to push that fluid back to the right atrium.
20:56
SPEAKER_03: Yeah.
20:57
SPEAKER_05: Okay.
20:58
SPEAKER_03: Okay.
20:59
SPEAKER_05: If you give a bunch of volume, and now your right atrial pressure is 10, it went up from like three to ten, your venual pressure probably hardly changed.
21:12
SPEAKER_05: Maybe it went from 12 to 13.
21:15
SPEAKER_05: Now that gradient is only three.
21:18
SPEAKER_05: So while you have a bunch of fluid in your heart and you have a bunch of fluid in your veins, you don't have a gradient that's pushing the blood back to the heart to allow the heart to stretch to then squeeze.
21:31
SPEAKER_05: So it actually can make things a lot worse, a lot worse.
21:35
SPEAKER_05: Like they used to say, titrate to a CVP of eight to twelve is what they said 10, 20 years ago.
21:42
SPEAKER_05: And then they were like, oh, wait, don't do that.
21:45
SPEAKER_05: That's never turned out to be good because all it does is it while it gives you volume, it it actually drops your gradient and you're actually delivering less blood because you don't have a gradient to push it there.
22:00
SPEAKER_03: Yeah.
22:01
SPEAKER_03: So you're just changing that that it's not as much of a high to low pressure area.
22:07
SPEAKER_03: It's kind of like high to medium pressure.
22:10
SPEAKER_05: And you have the blood there, you're just not pushing it forward at the same speed.
22:18
SPEAKER_05: So if you start vasopressors, vasopressors will squeeze the vinults to a certain amount and will increase your vine pressure and kind of restore that gradient a little bit.
22:27
SPEAKER_05: So that you could do that, but like just giving volume isn't going to get you there.
22:32
SPEAKER_05: So now we've kind of changed the way that we've thought about stuff and said, please stop like looking at these values as good values.
22:41
SPEAKER_05: Like in fact, the American Heart Association said if you have a CVP of eight to 12, you need to start diuresing them.
22:49
SPEAKER_05: Uh, because that that's too much.
22:52
SPEAKER_05: You're you're you're losing that gradient to be able to get venous return.
22:55
SPEAKER_05: You're over distending your your right ventricle, just a lot of things that are overall wrong with it.
23:01
SPEAKER_05: Um but it's that venous return that is becomes your preload, and so you're loading the ventricle with your venous return to allow it to squeeze and then move forward and then kind of go, and that goes around your body that way.
23:13
SPEAKER_05: So that is the Gitan Venus return curve.
23:16
SPEAKER_05: And if you want to read about Giten, he's there's a bunch of like articles and things uh if you want to go down that road with it.
23:24
SPEAKER_01: When was that?
23:25
SPEAKER_01: I'm just curious.
23:25
SPEAKER_01: Do you know off the top of your head?
23:27
SPEAKER_05: So long ago.
23:28
SPEAKER_05: I don't know off the top of my head, but it wasn't like published in 2000.
23:32
SPEAKER_05: Like this was like before things were like, hey, don't do that.
23:37
SPEAKER_05: Do that.
23:39
SPEAKER_01: Yeah.
23:40
SPEAKER_01: Don't do that.
23:41
SPEAKER_01: Don't kill the animal.
23:42
SPEAKER_01: Don't kill the dog.
23:43
SPEAKER_01: Got it.
23:44
SPEAKER_03: Well, you taught you say it, you tell me that it's too on the anniversary of my dog's passing.
23:50
SPEAKER_05: Sorry.
23:51
SPEAKER_05: I'm sorry about that.
23:56
SPEAKER_00: Sorrows, sorrows.
23:58
SPEAKER_00: Sorrows, sorrows, prayers.
24:05
SPEAKER_00: Sorrows, sorrows, sorrows.
24:08
SPEAKER_00: Sorrows.
24:10
SPEAKER_00: Sorrows, prayers.
24:14
SPEAKER_00: Sorrows, prayers.
24:18
SPEAKER_02: Anyway, so sad.
24:20
SPEAKER_02: So sad sorrows.
24:25
SPEAKER_02: Sorry, internet meme.
24:27
SPEAKER_02: Yeah, sorry.
24:29
SPEAKER_05: And that's the part I wanted to get off like the beginning of it, right?
24:34
SPEAKER_05: Like how much we have intervascular, how much we have interstitial, how we keep blood intervascular, and then like how we push it around.
24:42
SPEAKER_05: Now, I don't know how much it matters.
24:45
SPEAKER_05: A little like side thing to the Starling equation.
24:48
SPEAKER_05: The the Starling equation was under the assumption that we kind of we'd leak fluid out around our arterioles, like at the beginning of our capillaries, like into the organs.
25:00
SPEAKER_05: And then the thought process was we like sucked them back up into the venules like on our way back.
25:05
SPEAKER_05: That was what the thought process was.
25:07
SPEAKER_05: We've since proved that that's not correct.
25:12
SPEAKER_05: The way the the we we get our interstitial fluid, like a lot of it back into our intrabascular system through like our lymphatics, through like our thoracic duct and everything like that, as opposed to just like pushing it back in on our venual side.
25:27
SPEAKER_05: But the Starling equation, uh, when it was first introduced, was the idea that we would we would change our hydrostatic oncotic enough to leak it out into the organs, and then it would change back in the venules to like pull it back up.
25:40
SPEAKER_05: That's a little overly simplified, but m more that it mobilizes it uh back through the lymphatic system.
25:48
SPEAKER_05: Interesting.
25:49
SPEAKER_05: Um get that kind of part out of it, and now we can talk about fluids.
25:57
SPEAKER_05: So when we talk about like giving fluids, it's important to know why you're giving fluids.
26:05
SPEAKER_05: So when you're giving fluids, there's either resuscitative fluids, there's replacement fluids, and then there's maintenance fluids.
26:15
SPEAKER_05: So it depends on what you want to do with it.
26:19
SPEAKER_05: So we can go down that list.
26:21
SPEAKER_05: So resuscitative fluids mean I'm trying to resuscitate the person.
26:25
SPEAKER_05: They are in shock or they're hypotensive, and I'm trying to resuscitate, I'm trying to restore their oxy delivery, their cardiac output so that they're delivering enough oxygen to their organs.
26:36
SPEAKER_05: So if you want to give fluids for somebody in shock, you think that they are on the bottom part of the starling curve, as in if you give them more volume, you'll go higher up on the starling curve, that they want that preload.
26:53
SPEAKER_05: So patients that would need that would be hypovolemic shock.
26:57
SPEAKER_05: They are intravascularly deplete.
26:59
SPEAKER_05: You're giving them volume back because they're super low on the starling curve.
27:03
SPEAKER_05: They can't get enough blood pumped around because they don't have enough volume in their heart to be able to pump it around.
27:11
SPEAKER_05: And distributive shock, you're in the same boat.
27:14
SPEAKER_05: You don't have that volume that you need to account for their issues that are going on.
27:20
SPEAKER_05: And you're hypotensive because you're vasodilated and you're hoping to replace some of that volume.
27:26
SPEAKER_05: I talked about it in a previous episode where you take a four-liter bucket and then you dilate it out to a six-liter bucket.
27:34
SPEAKER_05: You now don't have a full bucket.
27:36
SPEAKER_05: You want to give them fluid to fill that bucket up while you're trying to shrink that bucket back down.
27:42
unknown: Yeah.
27:42
SPEAKER_05: So if you're giving replacement fluids, you're saying, I'm trying to replace the fluid that is no longer there, or I'm trying to replace the fluid that is like relatively not there when you dilate out in distributive shock.
27:56
SPEAKER_05: Replacement fluid is just abnormally lost volume.
28:02
SPEAKER_05: So if you're talking about just everyday life, that's going to be maintenance fluid.
28:09
SPEAKER_05: If you're talking about somebody that is vomiting or having a large amount of diarrhea or having a high output ostomy, or has a fistula, or something that's causing you to lose a lot of volume that is abnormal, then you want to replace that volume.
28:29
SPEAKER_05: That is replacement fluid.
28:31
SPEAKER_05: So that is not typical.
28:33
SPEAKER_05: Like people aren't out in everyday life losing like two liters out of their NG tube, or people aren't having like these large amounts of outputs.
28:41
SPEAKER_05: These are things in the hospital where you're like, hey, we have our everyday losses, but we also have this extra losses.
28:48
SPEAKER_05: This is what I'm trying to replace.
28:50
SPEAKER_05: The other or the last one is maintenance fluid.
28:53
SPEAKER_05: And this becomes a thing that just drives me insane, right?
28:57
SPEAKER_05: Like as soon I can I go to bed tonight and I don't I don't put an IV in myself and I don't like give myself maintenance fluid uh and be like, I was NPO.
29:09
SPEAKER_05: You have to give maintenance maintenance fluid every time they're NPO.
29:12
SPEAKER_05: And I'm just like, that's weird that I can go throughout the day without maintenance fluid, uh, but these patients can't.
29:20
SPEAKER_05: If you look at the literature, I'll go through the arguments, but like if you're hanging out, living your normal life, when we breathe out, uh it is humidified.
29:33
SPEAKER_05: Like it has a certain amount of moisture in it.
29:35
SPEAKER_05: And us breathing out, we end up losing about 400 milliliters a day of insensible losses.
29:44
SPEAKER_03: Yeah.
29:45
SPEAKER_05: Same thing with our skin.
29:47
SPEAKER_05: Like we it like it evaporates off of us, we have insensible losses.
29:51
SPEAKER_05: We can't sense that we're losing them.
29:54
SPEAKER_05: And that's another 400 milliliters a day.
29:58
SPEAKER_05: So about 800 milliliters of insensible losses.
30:04
SPEAKER_05: What people don't talk about that goes down a thing is that we technically also have some insensible gains.
30:11
SPEAKER_05: We actually make water in our body, if you remember, through uh glycolysis to through the TCA cycle, through the electron transport chain, is that as we make ATP, the end product of the electron transport chain is ATP and water.
30:29
SPEAKER_05: You got to reach reach back to go through all that type of thing with it.
30:33
SPEAKER_05: And so we end up making about 400 milliliters a day of water as we make energy, as we make ATP.
30:42
SPEAKER_05: So the net loss is about 400 milliliters a day of insensible losses, like that you're not sensing that you're losing day-to-day.
30:53
SPEAKER_05: Sensible losses would be like as you go and and and urinate, then obviously that you can see that that's sensible like on the thing.
31:02
SPEAKER_05: These are just like insensible losses on there.
31:04
SPEAKER_05: So it's not that much.
31:05
SPEAKER_05: It's 400 milliliters.
31:07
SPEAKER_05: If you divide that over 24 hours, that's less than 20 milliliters per hour.
31:13
SPEAKER_05: And it's very much hypotonic.
31:16
SPEAKER_05: Like you're not losing just salt water, you're losing salt, but you're mainly losing water as you go through there.
31:24
SPEAKER_05: So if you want to replace it, you would want to replace it with a hypotonic solution, but it would be at a very low rate for normal stuff with it.
31:34
SPEAKER_05: So if you go across it and say, like, what are maintenance fluids?
31:39
SPEAKER_05: If you wanted to say maintenance fluids were 30 milliliters an hour of half normal saline, that could be an argument.
31:48
SPEAKER_05: I would give you that argument.
31:50
SPEAKER_05: If you really wanted to do that, that would be fine.
31:53
SPEAKER_05: Anything above that is not being given for insensible losses or maintenance fluid.
32:00
SPEAKER_05: If you're saying, oh, they have a fever, if you have a fever, you're going to lose more volume just for having a fever.
32:05
SPEAKER_05: But that actually would qualify as replacement fluid because that would be abnormal.
32:09
SPEAKER_05: If they have an ostomy, if they have diarrhea, if they have a fistula, you can increase that volume, but it it would be you're adding maintenance, you're adding replacement to that maintenance.
32:21
SPEAKER_05: So if you're gonna say, I'm just gonna give them maintenance fluid at 125 an hour, you're giving them three liters of fluid over 24 hours.
32:32
SPEAKER_05: Three liters of fluid is a lot of fluid.
32:35
SPEAKER_05: If you're giving half normal saline, if you think about where you're at with it, is you're giving them three liters of fluid, which a liter is 2.2 pounds.
32:44
SPEAKER_05: So you're giving them 6.6 pounds of fluid over a day.
32:49
SPEAKER_05: That's a lot of fluid to just pump into someone's vascular system where they're just directly putting it in there.
32:56
SPEAKER_05: It also is a decent amount of salt.
33:00
SPEAKER_05: It's going to be 13 and a half grams of salt.
33:03
SPEAKER_05: So if you talk about having somebody on like a low sodium diet, you just gave them about four grams of salt uh in maintenance fluid.
33:12
SPEAKER_05: Or four grams of sodium, 13 and a half grams of salt.
33:18
SPEAKER_05: So it always like, especially, you know, you put somebody at, you're like, oh, they're hypertensive or they have hard, I'm gonna put them on a two gram low sodium diet.
33:26
SPEAKER_05: And then they're like, oh, they're MPO, I'm gonna put them on maintenance fluid, and then you give them four grams of sodium just in their maintenance fluid.
33:34
SPEAKER_05: That part is just like, what are we doing?
33:36
SPEAKER_05: Like you can't, you can't say, but you can't say, oh, they need a low amount of salt, and then just start hammering them with salt.
33:43
SPEAKER_05: And so it's yeah, if you want them to have the salt, let them eat.
33:45
SPEAKER_03: Yeah, some good things.
33:47
SPEAKER_05: Like put it in the thing.
33:48
SPEAKER_03: Let them taste some food, some good food.
33:50
SPEAKER_03: Um hospital food, especially.
33:55
SPEAKER_05: So it it's something to consider with it.
33:58
SPEAKER_05: And so, like, if you look at the literature, um, and they they've done a lot of literature in just like medical patients that just says all that extra fluid leads to just worse outcomes, worse uh ileus, worse kidney function, liver function, breathing, all the above.
34:18
SPEAKER_05: And it's in surgical literature.
34:20
SPEAKER_05: So they've done multiple studies that compared their maintenance fluid at either 30 mls per hour or like 100, 125 milliliters an hour.
34:29
SPEAKER_05: And the ones that got 30 mls per hour did significantly better.
34:33
SPEAKER_05: They had quicker return of bowel function, better wound healing, less like ICU days, less ventilator days, just across the board did better.
34:42
SPEAKER_05: But it's just hard, it's hard to change your training when you've just been trained your whole career that just says, oh, this person's NPO.
34:51
SPEAKER_05: I need to start 125 milliliters an hour, 75 milliliters an hour, 100 milliliters an hour of half normal saline or normal saline or whatever you want to do with it.
35:02
SPEAKER_03: Yeah.
35:02
SPEAKER_03: I do remember being taught that as a nurse, and there I had a patient and they were end stage renal and they kept going hypoglycemic and they did not order maintenance fluids, and I was freaking out about it.
35:15
SPEAKER_03: I was like a new grad nurse.
35:16
SPEAKER_03: I was like, I was freaking out about it for like four hours.
35:19
SPEAKER_03: I was like, we don't have maintenance fluids.
35:21
SPEAKER_03: And finally I was like, Do you want to order some maintenance fluids with dextros?
35:24
SPEAKER_03: So they they're not hypoglycemic, and they're like, No, because they're end-stage renal and they actually can't tolerate that.
35:32
SPEAKER_03: And I was like, Oh.
35:35
SPEAKER_03: Okay.
35:36
SPEAKER_03: You're right.
35:37
SPEAKER_03: You're right.
35:39
SPEAKER_03: But it had been hammered so much to me in nursing school, like maintenance fluids, maintenance fluids, maintenance fluids, NPO, you need fluids.
35:47
SPEAKER_03: And I was like, Yes.
35:49
SPEAKER_03: Yes.
35:50
SPEAKER_05: I mean, I I remember having it that like we had a patient that was just living their life, they'd already eaten breakfast.
35:57
SPEAKER_05: We they were fine.
35:59
SPEAKER_05: Everyone was fine with them.
36:00
SPEAKER_05: And then um somebody, I think cardiology wanted to do a procedure on them and they made them NPO.
36:07
SPEAKER_05: It's like, okay, you know, we we've all skipped lunch sometimes.
36:12
SPEAKER_05: And they called like three times, being like, Have you started the maintenance fluids?
36:16
SPEAKER_05: We made them NPO.
36:16
SPEAKER_05: And I was like, what do you think is happening in this in this time period?
36:21
SPEAKER_05: That as soon as you make them NPO, they just start like walk out to the desert and they're just like they're just like shriveling up.
36:28
SPEAKER_05: Like we make people MPO at home.
36:31
SPEAKER_05: They'll be MPO for 16 hours at home.
36:34
SPEAKER_05: They'll be like, Don't eat anything after midnight.
36:37
SPEAKER_05: Your surgery's at 1 p.m.
36:39
SPEAKER_05: and we're they're just hanging out at home minding their business, not on IV fluids.
36:43
SPEAKER_05: But if you come into a hospital, if you're not getting those IV fluids, then that is like the worst thing that could ever happen.
36:51
SPEAKER_01: I could probably use maintenance fluids.
36:53
SPEAKER_01: Yeah, Abby could.
36:55
SPEAKER_01: For sure.
36:57
SPEAKER_01: Like they were well enough to eat breakfast.
36:59
SPEAKER_05: Yeah.
36:59
SPEAKER_01: Yeah.
37:00
SPEAKER_05: They're gonna be fine.
37:04
SPEAKER_05: And so there's that whole thing with thing is understanding what you're gonna give whenever you're gonna give it.
37:10
SPEAKER_05: I think it's also important to say how you're gonna give those fluids.
37:14
SPEAKER_05: If you're gonna give maintenance fluids, like I said, it should be hypotonic.
37:17
SPEAKER_05: If you're gonna give replacement or resuscitative fluid, it should be isotonic.
37:22
SPEAKER_05: If you're giving replacement fluid, you just want to like replace it, right?
37:26
SPEAKER_05: Like uh if you've ever had like a post-obstructive diuresis, like they had BPH, they had like over a liter in their bladder, you put a folie in and they're just pouring urine out, right?
37:36
SPEAKER_05: They're putting out like 500 an hour.
37:38
SPEAKER_05: And so you're like, hey, whatever they put out in their folio, just put that amount of replacement fluid back.
37:45
SPEAKER_05: That way they they don't get that post-obstructive diuresis and get too dry.
37:49
SPEAKER_05: And that's something that it's just like you replace it one to one.
37:52
SPEAKER_05: If you, if you have a large output ostomy or you have a large output I G tube, and they're like, there was 300 in their EG tube in their NG tube for this hour, just be like, okay, give them 300 of fluid back, you know, like that type of stuff with it.
38:06
SPEAKER_05: So you don't necessarily have you can give it back like over that hour, or you can average it out over three hours.
38:12
SPEAKER_05: Like it's not that urgent of a thing to do.
38:15
SPEAKER_05: With resuscitative fluid, the idea is that you're resuscitating them, like they're in shock, they're hypotensive.
38:21
SPEAKER_05: You want to do it quickly, but you also want to do it quickly in the idea that you want to see if it's working.
38:28
SPEAKER_05: Like your assumption is that as you put it into their intravascular space, they should go higher up on the starling curve and their cardiac output should go up.
38:38
SPEAKER_05: So either their blood pressure should go up or their heart rate should come down, one or the other.
38:44
SPEAKER_05: Some people respond by like, oh, their heart rate was 130.
38:47
SPEAKER_05: Now it's down to 110 after we gave that liter of fluid.
38:50
SPEAKER_05: So if you're going to give resuscitative fluid, you should give it as a bolus.
38:56
SPEAKER_05: And a bolus doesn't mean like put it on the 999 and be like, let's give a liter over an hour.
39:03
SPEAKER_05: That's not a bolus, that is a liter of fluid over an hour.
39:06
SPEAKER_05: A bolus is put it on a pressure bag and pressure it in there, and you can actually see if that bolus is working to get higher up on the Starling curve and improve your hemodynamics.
39:18
SPEAKER_05: And I don't think people do enough of that.
39:21
SPEAKER_05: I think we've gotten very complacent in saying, oh, the order in electronic orders just says give a liter over an hour or give 500 over an hour for a lot of institutions, as opposed to saying, hey, if we're giving this, go get a pressure back, go put it in a large bore IV.
39:40
SPEAKER_05: Let's give it over a short amount of time so we can truly see are they fluid responsive?
39:45
SPEAKER_05: Are they responding to our boluses or resuscitation fluid?
39:49
SPEAKER_03: Yeah.
39:50
SPEAKER_03: I will say, at least on the floor, having been a former floor nurse, like we weren't really allowed to pressure bag.
39:59
SPEAKER_05: Um but I mean if you're in shock, like you sh just shouldn't be on the floor with it, or if you're like that hypertensive.
40:07
SPEAKER_03: But yeah, but sometimes we're holding them until the there's an ICU bed ready.
40:12
SPEAKER_03: But I will say, and I don't know how kosher this is.
40:15
SPEAKER_03: So again, this isn't this isn't advice.
40:17
SPEAKER_03: This is just how I did it.
40:20
SPEAKER_03: I would get four channels and get a bunch of small IV bangs, put them all into one and 999 them at the same time.
40:31
SPEAKER_03: So then they're getting two, they're getting the same amount of volume.
40:38
SPEAKER_03: But yeah.
40:39
SPEAKER_05: I mean, you could definitely like anything to like increase the rate that it's going in is going to allow you to see it because everyone like if you order a liter of fluid and you look at their vitals at the beginning of the hour versus vitals at the end of the hour, and you just say, were they better?
40:57
SPEAKER_05: Did it help?
40:58
SPEAKER_05: And sometimes it's hard to know, right?
41:00
SPEAKER_05: You're like an hour in.
41:01
SPEAKER_05: Like, did it help?
41:02
SPEAKER_05: And you're like, I don't know, not really.
41:05
SPEAKER_05: Whereas if you give it over a very short amount of time, you really get a better idea of did it help?
41:10
SPEAKER_05: If it didn't help, don't keep giving it.
41:12
SPEAKER_05: If you're like, I gave 500 milliliters over a pressure bag and nothing happened, then it's not like the next 500 is a magical 500.
41:21
SPEAKER_05: It's likely not to be helpful either.
41:23
SPEAKER_03: So you mean if the first five liters weren't didn't work specifically.
41:29
SPEAKER_05: You gotta reach for that special that special six-liter bag in like the back of the supply area.
41:35
SPEAKER_05: Yeah.
41:35
SPEAKER_05: And you're like, that's the magical one.
41:38
SPEAKER_02: The one you had to like dust off.
41:40
SPEAKER_05: All of a sudden all the pressers come off.
41:42
SPEAKER_05: You're like, I am so glad I reached for that six liter.
41:46
SPEAKER_05: Um yeah, I mean, that's how people treated it for a long time.
41:50
SPEAKER_01: For the nurses out there, if you're new a nurse, you ain't gotta have a pressure bag.
41:54
SPEAKER_01: You can squeeze the bag.
41:55
SPEAKER_01: You can squeeze it.
41:56
SPEAKER_01: So just we were out of pressure bags one of those times when everything was back ordered.
42:01
SPEAKER_01: There's a little new grad and they were panicking because they're like, we're supposed to be pressure bagging it.
42:06
SPEAKER_01: We don't have any, blah, blah, blah.
42:07
SPEAKER_01: And I was like, we can crack a code card and I'll s and I'll or I'll squeeze it in.
42:11
SPEAKER_01: And it's like blew their mind.
42:12
SPEAKER_01: Like this that's how a pressure bag works.
42:14
SPEAKER_01: You're pressing the bag.
42:17
SPEAKER_01: Blew their mind.
42:18
SPEAKER_01: Sorry.
42:20
SPEAKER_01: Yeah, not you, Abby, but I'm good.
42:27
SPEAKER_05: So yeah, so like that, there's like different ways to give the fluid to whenever you're giving it.
42:34
SPEAKER_05: Now we can have a conversation about like the type of fluid.
42:40
SPEAKER_03: Hi everyone.
42:41
SPEAKER_03: Part two of fluid management is going to be coming to you next week.
42:45
SPEAKER_03: Make sure you hit the like, follow button, send us in any of your questions about fluids for Dr.
42:51
SPEAKER_03: Michael, and we'll make sure to get them answered either on next week's episode or in a follow-up episode.
42:58
SPEAKER_03: Until next time, bye.
43:07
SPEAKER_00: Step into the light where the stories come.