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.

    00:04 So as we talk about the cardiovascular system, think about what needs to happen.

    00:09 We're supporting an entire other human being.

    00:13 That's a lot of work.

    00:15 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 fluid, the heart is actually working harder.

    00:31 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 experienced 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.

    00:49 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.

    00:59 Next, we want to think about the position of the heart.

    01:01 So, what happens is it actually moves.

    01:04 So the heart sort of leans over to the left.

    01:07 And so when that happens, we call that dextroversion.

    01:11 Cardiac output is actually also going to increase.

    01:14 Remember, cardiac output is the amount of blood that comes out during a pump, right? We need more blood flow.

    01:21 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.

    01:33 And this comes under the influence of progesterone.

    01:37 Now, I want you to remember this, estrogen makes things fluffy and big.

    01:41 We've already talked about that in terms of proliferation of the breast.

    01:44 Progesterone is the chill factor. It makes things relax.

    01:49 So it causes relaxation in the vessels.

    01:52 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.

    02:14 It's gonna 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.

    02:26 It's not unusual to see someone with a blood pressure of 100/60, when they're 15, 16, or 17 weeks. That's normal.

    02:33 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.

    02:43 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.

    02:50 So a 10 to 15 beat increase, totally normal.

    02:53 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? 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.

    03:21 Remember the effect of progesterone, it chills things out.

    03:25 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.

    03:53 We have a big belly with Cletus the fetus inside and we lie down on our back and then we have all the way to our uterus pushing down on our vena cava.

    04:03 What do you think is going to happen? Exactly, your blood pressure is going to drop.

    04:07 The client is going to report feeling dizzy and lightheaded.

    04:11 So what do we tell clients to do? Not lay flat on your back after 20 weeks.

    04:15 That's called vena cava syndrome.

    04:19 Now, let's talk about the hematologic system.

    04:22 So in the hematologic system again, the systems are going to support the pregnancy.

    04:27 We haven't 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 factor is also increase. Let's talk about why.

    04:42 So we didn't always deliver in our homes or in hospital and a nice safe place where you could rest after you have your baby.

    04:50 We used to be nomadic creatures.

    04:51 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.

    05:04 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.

    05:13 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.

    05:23 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.

    05:33 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.

    05:44 We have an increase in oxygen carrying capacity.

    05:48 We need more oxygen, so the red blood cells are able to carry more oxygen.

    05:53 We are hypercoagulable.

    05:55 That way after delivery, the bleeding will stop.

    05:59 The bohr effect is in effect.

    06:01 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.

    06:16 So, I want to go over one really important element.

    06:19 I want you to take a look at the blood pressure.

    06:21 If you can see when we start off in a non pregnant state, we have a baseline blood pressure.

    06:26 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.

    06:33 And then by the time we get to the third trimester, the blood pressure goes back up almost a baseline.

    06:39 We know that in the second trimester that is caused by the relaxation of the vasculature, the blood pressure drops.

    06:47 So why does the blood pressure go up in the third trimester? Well, guess what, we have a baby that's growing, and they need a lot of extra blood flow.

    06:55 So the blood flow tends to return to baseline to make sure the baby gets enough oxygen so that they can breathe.

    07:03 Now let's talk about renal system changes.

    07:06 So what's going on with the kidneys as a result of pregnancy? The kidneys are actually going to enlarge.

    07:12 Everything enlarges because it's under the influence of what? Estrogen. Exactly.

    07:19 Remember, estrogen makes things fluffy.

    07:22 The ureters are also going to dilate and become torturous.

    07:26 Now that sounds bad.

    07:28 And it's a little weird, but it just means that the ureters are kind of not straight anymore.

    07:32 They're wiggly. Okay.

    07:33 The dilation is under the influence of what hormone? Progesterone, the chill factor. Exactly.

    07:42 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.

    07:54 So we want to be mindful that pregnant clients are at increased risk for infection because of the dilation of the ureters.

    08:02 Also, bladder tone decreases.

    08:05 Again, when we think about tone, we think about relaxation, who is the culprit? Progesterone.

    08:12 So why does it matter that bladder tone decreases? Well, let's think about it.

    08:17 Let's talk about a balloon, because that's what the bladder is like.

    08:21 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.

    08:32 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.

    08:49 Are you getting the picture? We're going to have a lecture about pregnancies discomforts.

    08:53 And you might want to think about that for that lecture.

    08:57 When we think about our labs, so are labs that are related to kidney function, what we're gonna find is the glomerular filtration rate is actually going to increase.

    09:05 So, I like to think about the membranes in the kidneys like cheese cloth, that under normal circumstances, everything is really tight and close together.

    09:14 However, under the influence of progesterone, we start to develop space.

    09:19 And that allows for things like protein and glucose and all kinds of things to leak through.

    09:25 So we may find that to be the case in this situation.

    09:29 We're going to have a decrease in serum creatinine, we're going to also have a decrease in BUN.

    09:34 So remember, cheesecloth, glucosuria and protein, having a trace of that in the urine, totally to be expected.

    09:43 Not 1+, not 2+, or 3+ that's not normal, but a trace, completely understandable and expected.

    09:53 Let's take a second and review the changes in the cardiovascular, hematologic and renal system.

    09:59 We have increases in clotting factors, heart rate, cardiac output, blood volume, glomerular filtration rate, proteinuria, RBC mass, and the WBC count.

    10:14 There are decreases in the systemic vascular resistance or SPR, the hematocrit, the hemoglobin, BUN and creatinine, ureteral motility.

    10:25 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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