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Pharmacological Treatment and Prevention of Preeclampsia (Nursing)

by Jacquelyn McMillian-Bohler

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    00:01 Now we're ready to talk about the medications that are used to manage preeclampsia.

    00:06 There are several categories that might come into play.

    00:09 So, let's review those now.

    00:11 Calcium channel blockers, Beta-blockers, Nonsteroidal anti-inflammatories, Antiadrenergic, and Diuretics.

    00:20 So let's break those down, so we can think about how those might work in preeclampsia.

    00:25 The first one, I'm probably the one you're going to hear the most often is magnesium sulfate.

    00:31 So magnesium sulfate is a calcium channel blocker, and it's also a neurotonic. So we get two benefits for this.

    00:37 So it's recommended for patients who have eclampsia or severe preeclampsia.

    00:42 And patients who've had a cesarean birth because of the preeclampsia, which indicates that it's most likely a severe case.

    00:49 The expected effects that are going to happen when we give magnesium sulfate are going to be a feeling of feeling flushed, having a metallic taste, fetal heart rate variability changes, somnolence, which means you're sort of feeling kind of drowsy, and a little quiet, and decrease reflexes.

    01:07 So, that's all well and good.

    01:09 But why do we give the magnesium sulfate? We give magnesium sulfate to prevent seizures.

    01:15 Say that three times, right now.

    01:18 We give magnesium sulfate to prevent seizures, and I'll let you do the last two on your own.

    01:24 Make sure that you understand that because we do not give magnesium sulfate to lower the blood pressure.

    01:30 Now, sometimes it might because it does relax smooth muscle, but that is not the indication. So don't get them confused.

    01:38 It's important that we have an antidote, for magnesium sulfate, in case we give too much.

    01:43 And that antidote is called calcium gluconate.

    01:46 That is the antidote for magnesium sulfate.

    01:48 It's given IV, and it's given very slowly.

    01:52 Let's talk more about the effects of magnesium sulfate.

    01:55 So one of the things it does is it sort of protects the endothelial cells.

    02:00 So it decreases the vasoconstriction and the damage that may occur from the preeclampsia.

    02:06 It also causes vasodilation, which can alleviate some of the cerebral schema that may happen as a result of the preeclampsia.

    02:14 It potentiates beta-blockers and it increases the potency and the duration of muscle relaxant.

    02:20 So that's good to know.

    02:22 It also increases bleeding time and decreases platelet activity.

    02:27 So that might be really important, we think about bleeding postpartum.

    02:32 I want you to take a look at this strip.

    02:33 Hopefully you remember it from our fetal monitoring lecture.

    02:37 But if not, let's take a peek here.

    02:39 So this is a strip from a client who could come in for maybe an induction of labor, maybe some preeclampsia severe, and they're on a fetal monitor.

    02:51 We see that we have moderate variability and a heart rate that's in normal range.

    02:56 We also see three contractions.

    02:58 But that's not really important for what we're going to talk about.

    03:00 Pay attention to what's going on in that green box.

    03:04 Now look at this.

    03:06 What do you notice? Do you notice that the variability has flattened out? So if you remember that the variability is caused by the play between the parasympathetic and sympathetic nervous system, and we know that magnesium sulfate tends to relax that interplay, then it makes sense of the variability would be smoothed out.

    03:26 So although this is not what we want, it's not a great strip, it doesn't really show that our fetus is particularly neurologically active.

    03:34 This is what we would expect, because likely mom is a little sedated, and this passes through the placenta, so the baby is going to be experiencing the very same thing.

    03:45 So in order to watch for complications of giving the magnesium sulfate, and to make sure the preeclampsia is not getting worse, the nurse will do something called Hourly Magnesium Sulfate Checks.

    03:57 So during those checks, they'll check for level of consciousness.

    04:00 So, talking to the client is probably good enough to elicit this.

    04:04 So making sure they know where they are.

    04:06 And they're rousable.

    04:08 Sometimes they'll feel sleepy, that's normal, but they should know where they are, what's going on, and have clear speech.

    04:14 We'll check the respiratory rate, because magnesium sulfate can slow the respiratory rate down to pretty low levels.

    04:22 So we want to make sure we're not overdosing them with magnesium sulfate.

    04:26 So a respiratory rate less than 12 would be a sign of potential toxicity.

    04:31 We're also going to check deep tendon reflexes.

    04:35 I'm taking it back to the beginning of the lecture.

    04:37 And remember, that hyperreflexivity may be a result of the preeclampsia.

    04:42 So, if we give magnesium sulfate, what should happen to the reflexes? Right, they should go down.

    04:49 They may go from 3+, which is considered hyperreflexic to maybe 2+ or 1+.

    04:56 But if we get to zero, then that may indicate that we're giving too much magnesium sulfate.

    05:02 So we don't really want zero, we just want it back down to a normal level.

    05:06 Do you remember how to do your clonus exam? There are very few times unless you work on neuro that you will actually do this test.

    05:12 So, I want to show it to you one more time.

    05:15 So, to check for clonus, you dorsiflex the foot, which means you pull the toes back towards the knee, and you let go, and you watch for taps of the foot.

    05:24 And you count those taps.

    05:26 Normally, there shouldn't be any taps.

    05:28 You dorsiflex the foot, it relaxes, no problem.

    05:31 If you have clonus, instead of flopping back over, it'll tap, like this.

    05:37 And that lets you know what's going on with neurologic irritability.

    05:41 The more clonus you have, and it can even be like this a tetanic clonus response lets you know that you're more likely to have a seizure.

    05:50 So, that can tell you, hopefully, that your magnesium is working.

    05:53 Someone who may present with clonus, You may find over time that the clonus disappears, or someone maybe has one bit of clonus, and it goes to two or it goes to the titanic, and that may mean you need to turn up your magnesium sulfate.

    06:08 We're also going to watch the blood pressure.

    06:11 Now, the blood pressure may decrease because of the magnesium sulfate.

    06:15 But again, that's not why we give it.

    06:19 We are checking the blood pressure because the preeclampsia may be getting worse.

    06:23 And that may be how we notice that.

    06:25 We're also going to check urine output.

    06:28 Not the magnesium is going to do anything to the urine, it doesn't really affect that system, but the preeclampsia does.

    06:35 And this is how the magnesium is actually going to be excreted.

    06:40 So if the urine output is limited because of the preeclampsia, then it sets us up for toxicity to the magnesium sulfate because there's no way for it to get out.

    06:49 And we're also going to check the heart rate because the magnesium can slow the heart rate.

    06:54 And a heart rate of less than 60 might be an indication of magnesium toxicity.

    06:59 Let's talk about a few other medications.

    07:01 The first one is hydralazine.

    07:03 So, maybe you've given this medication when you're on a cardiac unit for someone else with hypertension.

    07:08 This will work in this case too.

    07:10 It causes direct peripheral vasodilation.

    07:13 So that's going to help bring the blood pressure down.

    07:16 It also increases cardiac output and heart rate.

    07:19 So the dosages typically are about 5 mg IV up to 10 mg IM.

    07:24 And it can be given about every 20 to 30 minutes.

    07:27 The max dose for this IV is going to be 20 mg, and IM is going to be 30 mg.

    07:34 So thinking about what could happen when you give hydralazine.

    07:37 Sometimes we have some effects we have to be aware of and that is definitely the case here.

    07:41 So we give it to lower the blood pressure.

    07:44 We might lower it too much. And we may have hypotension and the client may begin to experience symptoms related to that.

    07:50 Or we can develop tachycardia where the heart rate begins to go up.

    07:53 So sometimes clients may feel a little strange when they take hydralazine.

    07:57 And we want to make sure that they are aware.

    08:00 The next medication is labetalol.

    08:02 So labetalol is a nonselective beta-blocker.

    08:05 And it helps to again, lower the blood pressure.

    08:08 So remember, magnesium sulfate is not what we give to decrease blood pressure.

    08:13 We're going to give these medications.

    08:15 So it's given IV for blood pressure is greater than 160/110.

    08:19 Hopefully, that's ringing a bell and letting you know that that goes along with someone who's experiencing, what? Severe preeclampsia. You got it.

    08:28 So someone with mild preeclampsia is not going to get labetalol.

    08:31 So, we give 200 to 1200 mg/dL in 2 to 3 divided doses.

    08:37 And patients who've had a history of asthma, or a history of bradycardia, they will not be candidates for this medication.

    08:46 Nifedipine.

    08:47 So this is a calcium channel blocker.

    08:49 And we give this in doses of 30 to 120 ml/dL.

    08:54 This is given intravenously for patients who have a blood pressure that's greater than 160/110.

    09:00 Severe preeclampsia.

    09:02 Expected effects with nifedipine are going to be flushing, peripheral edema, again, that reflex tachycardia, and potentially a headache from that rapid vasodilation.

    09:13 Methyldopa is another antihypertensive.

    09:15 And it reduces blood pressure by reducing the SVR or systemic vascular resistance.

    09:21 The dosage for this is 250 to 800 ml, and it's given PO q 8 hours.

    09:26 So this is not something we typically give at the bedside in the hospital.

    09:30 This is going to be given to someone unexpected management that's at home.

    09:35 Expected effects are going to be headache, flushing, tachycardia.

    09:39 So think about it.

    09:40 Anytime we give a medication to lower the blood pressure, the potential is going to be that we're going to have these reflexive responses.

    09:49 Just to review and let you know, and most often, most of the time your instructors are not going to require that you memorize all the dosage for each of these medications, but it's a good idea to have a range when you go clinical so you can maybe tell your preceptor, or your clinical instructor about them.

    10:04 So, magnesium sulfate.

    10:05 We typically give a 4-6 gram loading dose, And then there's a maintenance dose.

    10:10 We want to onboard and get it into the system, and then continue to give the magnesium sulfate until it's discontinued.

    10:17 The reason we give it is to decrease seizure activity and not for blood pressure.

    10:22 And the antidote is...

    10:25 Calcium gluconate. Awesome.

    10:27 Hydralazine.

    10:28 We're going to give 5 mg maybe IV, or we may give 10 mg IM, and that's going to be repeated every 20 to 30 minutes.

    10:37 And this is going to decrease the blood pressure by causing vasodilation.

    10:40 Labetalol.

    10:41 Again, is going to be given around 200-1200 ml/dL in divided doses.

    10:47 This is also going to decrease the blood pressure.

    10:50 Nifedipine is going to be 30 to 120 mg decreases the blood pressure through vasodilation.

    10:56 And methyldopa is going to be something that's given during the antepartum period 250 to 800 mg.

    11:02 This is a PO dose. And it also reduces SVR.

    11:07 I'm often asked by students, is there anything we can do to prevent preeclampsia? Now we, there's lots of research that's going on and I want to share with you what's up to date.

    11:17 But know that this information changes.

    11:18 And so when you watch this video, especially if it's a few years from now, you may want to go back, and double check, and see what's new, and hopefully they have some new options for treatment.

    11:28 So acetylsalicylic acid, 150 milligrams per day.

    11:31 There are some studies that show that it results in a 62% reduction in preterm deliveries, and preterm preeclampsia.

    11:39 So, that might be something to suggest if you're working in a high risk population.

    11:43 Calcium giving elemental calcium has shown some benefits.

    11:47 Vitamin C and vitamin E.

    11:49 unfortunately, have not shown to be particularly effective Zinc and vitamin D might be effective, but that evidence is not conclusive at this point.

    11:59 We have studies that are examining right now the effect of oxidative stress.

    12:04 And that's link between that and preeclampsia.

    12:07 And early studies right now are looking at the use of statins.

    12:10 And they're showing some promise with that as a possibility of preventing preeclampsia.

    12:15 The only thing that's really tried and true that works most of all, is reducing the risk for chronic hypertension, engaging in exercise, and diet, and stress reduction prior to pregnancy.

    12:26 That is the most important thing.

    12:28 So, when we think about wellness and how we can prevent complications, we want to think about that well before conception occurs.


    About the Lecture

    The lecture Pharmacological Treatment and Prevention of Preeclampsia (Nursing) by Jacquelyn McMillian-Bohler is from the course Hypertensive Disorders of Pregnancy: Preeclampsia (Nursing).


    Included Quiz Questions

    1. Increases the seizure threshold
    2. Reduces blood pressure
    3. Reduces deep tendon reflexes
    4. Relaxes smooth muscle
    1. Dilates blood vessels
    2. Increases bleeding time
    3. Feeling flushed
    4. Increases variability on the fetal heart monitor
    5. Feeling of restlessness
    1. Examine for bradycardia
    2. Assess for the presence of clonus
    3. Measure and document urine output
    4. Confirm increased deep tendon reflexes
    5. Prepare the antidote potassium chloride if toxicity occurs
    1. Labetalol
    2. Hydralazine
    3. Nifedipine
    4. Magnesium sulfate
    5. Vasopressin
    1. Reflex tachycardia and hypotension
    2. Reflex tachycardia and hypertension
    3. Reflex bradycardia and hypotension
    4. Reflex bradycardia and hypertension

    Author of lecture Pharmacological Treatment and Prevention of Preeclampsia (Nursing)

     Jacquelyn McMillian-Bohler

    Jacquelyn McMillian-Bohler


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