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Changes of the Cardiovascular, Hematologic, and Renal System during Pregnancy (Nursing)

by Jacquelyn McMillian-Bohler

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    00:01 Now, let's talk about changes in the cardiovascular system.

    00:05 So, as we talk about the cardiovascular system, think about what needs to happen, we're supporting an entire other human being.

    00:13 That's a lot of work. Keep that in mind as we go through this.

    00:17 So, first of all, the heart, that's responsible for moving all the blood and the oxygen through our body, has to work extra hard.

    00:25 So, as we have an increase of blood volume and fluid, the heart's actually working harder and because it's a muscle, what happens when we work out muscles? Well, not to mine, but everybody else's muscle gets bigger.

    00:38 So, the heart gets bigger and we experience cardiomegaly.

    00:42 So, this would be important for a nurse, maybe working in the emergency room or working somewhere else and we get a chest x-ray and you see the heart, now, ordinarily you might go, “Wow, that's a big heart,” but now, because you've listened to this lecture, you'll go, “That's cardiomegaly and that's normal for pregnancy.” Next, we want to think about the position of the heart.

    01:01 So, what happens, is it actually moves, so, the heart sort of leans over to the left and so when that happens we call that, “Dextroversion.” Cardiac output is actually also going to increase, remember cardiac output is the amount of blood that comes out, during a pump, right? We need more blood flow, this is going to increase by 30 to 50%.

    01:25 Our circulating blood volume is also going to increase by 45%.

    01:30 We may experience a drop in blood pressure mid pregnancy and this comes under the influence of progesterone.

    01:37 Now, I want you to remember this.

    01:38 Estrogen makes things fluffy and big, we've already talked about that, in terms of proliferation of the breast.

    01:44 Progesterone is the chill factor, it makes things relax, so, it causes relaxation, in the vessels.

    01:53 So, the blood pressure, is actually going to go down mid pregnancy, in response to that relaxation of the vessels.

    02:00 So, let's summarize those cardiovascular changes, because that was a lot.

    02:04 These are the things to remember, so, the PMI is going to move.

    02:07 We talked about how the heart leans, we're going to find the point of maximum impulse, in a different space, it's going to move up a little bit.

    02:17 Next, we need to remember that the blood pressure is going to change.

    02:20 The progesterone causes relaxation of the vessels, which is going to decrease the blood pressure, it's not unusual to see someone with a blood pressure of 100/60, when they're 15/16/17 weeks that's normal.

    02:34 We may experience an increased heart rate.

    02:37 Now, I'm saying increased, I don't mean tachycardia.

    02:41 Tachycardia, is never normal, but the heart, remember is trying to push all that extra blood through the body, so, it's going to do that a little bit faster, so, a 10 to 15 beat increase, totally normal.

    02:54 We may also notice because of all that extra blood volume and this change in the heart rate a low-grade systolic murmur.

    03:01 Now, a really good practice is when you hear something that's different, is to ask the client, if they noticed that before, have they ever been told they had a murmur.

    03:10 So, ask that question as well, but know, that a low-grade systolic murmur, is normal in pregnancy.

    03:17 Sometimes, you may also hear a split second heart sound, remember the effect of progesterone, it chills things out, it can actually chill out and relax the heart valves, so, they're not as efficient when they close.

    03:31 So, if you're listening with your stethoscope, you may actually hear this.

    03:35 In-fact just practicing listening to your heart sounds on a pregnant client, may give you some good practice in hearing things that would be abnormal any other time.

    03:44 Also, vena cava syndrome.

    03:46 What happens in this particular situation, is when the client is lying flat on their back, so, kind of get this picture in your head, we have a big belly with cletus the fetus inside and we lie down on our back and then we have all the weight of our uterus pushing down on our vena cava, what do you think is going to happen? Exactly, your blood pressure is going to drop, the client is going to report feeling dizzy and lightheaded, so, what do we tell clients to do? “Not lay flat on your back after 20 weeks,” that's called, “Vena Cava syndrome.” Now, let's talk about the hematologic system.

    04:22 So, in the hematologic system again, the systems are going to support the pregnancy, we have a 50% increase in plasma volume, so, the liquid part of the blood.

    04:33 We're not talking about the red blood cells, we're talking about the liquid, a 50% increase.

    04:38 Clotting factors also increase, let's talk about why.

    04:42 So, we didn't always deliver in our homes or in a hospital in a nice safe place, where you could rest after you have your baby, we used to be nomadic creatures and so, you might have your baby in a field and everybody else is leaving to go on to the next place.

    04:57 So, you need to have clotting factors, in order, to get your blood to stop after delivery, so, you can keep going with everyone else, so, this is a normal physiologic change, that our clotting factors are going to go up.

    05:09 Our red cell volume is going to increase, in terms of the size.

    05:14 So, not necessarily in terms of the number, but how big it is, and why does that matter? Well, remember that our red blood cells actually carry the oxygen, so, if the red blood cells are bigger, guess what they can carry more of? Oxygen, exactly right.

    05:30 We also have an increase in leukocyte production and that's going to be important, because we have a lot of factors that are going on inside the body and we need to be able to be responsive to that.

    05:40 Let's talk about the functional changes in the hematologic system, we have an increase in oxygen carrying capacity, we need more oxygen, so, the red blood cells are able to carry more oxygen, we are hyper coagulable, that way, after delivery, the bleeding will stop.

    05:59 The Bohr effect, is in effect and what that means is, there is an increased affinity to the red blood cells for oxygen, which is, what we need, when carbon dioxide levels are high.

    06:12 Now, I have a table here and there's a lot of information on this table, so, I want to go over one really important element, I want you to take a look at the blood pressure, if you can see, when we start off in a non-pregnant state, we have a baseline blood pressure and then as we move into the first trimester and into the second trimester, you see that dip in blood pressure that we talked about and then by the time we get to the third trimester, the heart rate goes back up, almost to baseline.

    06:40 We know that in the second trimester, that is caused by the relaxation of the vasculature, the blood pressure drops.

    06:47 So, what makes it go up in the third trimester? Well guess what? There's a big old uterus and that big old uterus changes, as the venous return and that makes the blood pressure go a little bit up and closer to normal.

    07:06 Now, let's talk about renal system changes.

    07:09 So, what's going on with the kidneys as a result of pregnancy.

    07:13 The kidneys are actually going to enlarge, everything enlarges, because it's under the influence of what? Estrogen. Exactly remember estrogen makes things fluffy.

    07:26 The ureters, are also going to dilate and become torturous, now that sounds bad and it's a little weird, but it just means that the ureters are kind of not straight anymore, they're wiggly, okay.

    07:37 The dilation is under the influence of what hormone? Progesterone. The chill factor. Exactly.

    07:46 Why is that important? Well, let’s see? If I dilate the structures that are on the way to the kidneys, that might allow bacteria to also travel with it as well, so, we want to be mindful that pregnant clients, are at increased risk for infection, because of the dilation of the ureters.

    08:06 Also, bladder tone decreases, again, when we think about tone we think about relaxation, who is the culprit? Progesterone.

    08:16 So why does it matter that bladder tone decreases? Well, let's think about it.

    08:21 Let's talk about a balloon, because that's what the bladder is like, if I had a balloon and I blew it up a couple of times, would my balloon ever go back to its normal shape? No. It would be a little soggy and a little floppy.

    08:36 The problem with the bladder, when it's a little soggy and a little floppy, is that we get urinary retention, which potentially, could set us up for a urinary tract infection, which, we're already at risk for, because our ureters are dilated and allow more bacteria to go through.

    08:52 Are you getting the picture? We're going to have a lecture about pregnancy discomforts and you might want to think about that, for that lecture.

    09:00 When we think about our labs, so, our labs are related to kidney function.

    09:04 What we're going to find is the glomerular filtration rate is actually going to increase, so, I like to think about, the membranes in the kidneys, like cheesecloth, that, under normal circumstances, everything is really tight and close together.

    09:17 However, under the influence of progesterone, we start to develop space and that allows for things, like protein and glucose and all kinds of things, to leak through.

    09:29 So, we may find that to be the case in this situation.

    09:32 We're going to have a decrease in serum creatinine, we're going to also have a decrease in BUN.

    09:38 So, remember cheesecloth, glucose urea and protein, having a trace of that in the urine, totally to be expected, not one plus, not two plus or three plus, that's not normal, but a trace, completely understandable and expected.

    09:57 Let's take a second and review the changes in the cardiovascular hematologic and renal system.

    10:03 We have increases in clotting factors, heart rate, cardiac output, blood volume, glomerular filtration rate, proteinuria, RBC mass and the WBC count.

    10:18 There are decreases in the systemic vascular resistance or SVR, the hematocrit, the hemoglobin, BUN and creatinine, urinal motility, did you get all of that? Okay let's move on.


    About the Lecture

    The lecture Changes of the Cardiovascular, Hematologic, and Renal System during Pregnancy (Nursing) by Jacquelyn McMillian-Bohler is from the course Physiological Changes in Pregnancy (Nursing).


    Included Quiz Questions

    1. Cardiomegaly
    2. Endocarditis
    3. Cardiac tamponade
    4. Myocarditis
    1. Cardiac output increases
    2. The heart is displaced up and to the left
    3. Circulating blood volume decreases
    4. Blood pressure increases
    1. A heart rate of 135
    2. A blood pressure of 99/65
    3. A low-grade systolic murmur audible during auscultation of the heart
    4. A split S2 audible during auscultation of the heart
    1. Plasma volume increases
    2. Leukocyte production increases
    3. Clotting factors decrease
    4. Red cell volume decreases
    1. Kidneys enlarge
    2. Increase in glomerular filtration rate
    3. Bladder tone increases
    4. Ureters constrict

    Author of lecture Changes of the Cardiovascular, Hematologic, and Renal System during Pregnancy (Nursing)

     Jacquelyn McMillian-Bohler

    Jacquelyn McMillian-Bohler


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