Hypertension in Pregnancy

Lianne Beck, MDAssistant ProfessorEmory Family Medicine

OBJECTIVES

Know criteria for the diagnosis of chronic hypertension, gestational hypertension and preeclampsia

List criteria for the diagnosis of severe preeclampsia/HELLP syndrome

Discuss current management considerations

Introduction Most common medical complication of pregnancy 6 to 8 % of gestations in the US. In 2000, the National High Blood Pressure

Education Program Working Group on High Blood Pressure in Pregnancy defined four categories of hypertension in pregnancy:

Chronic hypertension Gestational hypertension Preeclampsia Preeclampsia superimposed on chronic hypertension

Chronic Hypertension Defined

1. BP measurement of 140/90 mm Hg or more on two occasions

2. Before 20 weeks of gestation OR Persisting beyond 12 weeks postpartum

Chronic Hypertension

Treatment of mild to moderate chronic hypertension neither benefits the fetus nor prevents preeclampsia.

Excessively lowering blood pressure may result in decreased placental perfusion and adverse perinatal outcomes.

When BP is 150 to 180/100 to 110 mm Hg, pharmacologic treatment is needed to prevent maternal end-organ damage.

Treatment of Chronic Hypertension Methyldopa , labetalol, and nifedipine most

common oral agents.

AVOID: ACEI and ARBs, atenolol, thiazide diuretics

Women in active labor with uncontrolled severe chronic hypertension require treatment with intravenous labetalol or hydralazine.

Gestational Hypertension Formerly called PIH (Pregnancy Induced HTN)

HTN without proteinuria occurring after 20 weeks gestation and returning to normal within 12 weeks after delivery.

50% of women diagnosed with gestational hypertension between 24 and 35 weeks develop preeclampsia.

Older Criteria for Gestational HTN 30/15 increase in BP over baseline levels No longer appropriate 73% of patients will exceed 30 mm systolic

and 57% will exceed 20 mm diastolic

Preeclampsia New onset hypertension with proteinuria after 20

weeks gestation.

Resolves by 6 weeks postpartum.

Characterized as mild or severe based on the degree of hypertension and proteinuria, and the presence of symptoms resulting from involvement of the kidneys, brain, liver, and cardiovascular system

Risk FactorsFACTOR RISK RATIO

Renal disease 20:1

Chronic hypertension 10:1

Antiphospholipid syndrome

10:1

Family history of PIH 5:1

Twin gestation 4:1

Nulliparity 3:1

Age > 40 3:1

Diabetes mellitus 2:1

African American 1.5:1

Diagnostic Criteria for Preeclampsia1. SBP of 140 mm Hg or more or a DBP of 90

mm Hg or more on two occasions at least six hours apart after 20 weeks of gestation AND

2. Proteinuria – 300 mg in a 24-hour urine specimen or 1+ or greater on urine dipstick testing of two random urine samples collected at least four hours apart.

A random urine protein/creatinine ratio < 0.21 indicates that

significant proteinuria is unlikely with a NPV of 83%. Generalized edema (affecting the face and hands) is often present

in patients with preeclampsia but is not a diagnostic criterion.

HELLP Syndrome

Is a variant of severe preeclampsia Occurs in up to 20% of pregnancies

complicated by severe preeclampsia. Variable clinical presentation; 12 to 18% are

normotensive and 13% do not have proteinuria.

At diagnosis, 30% of women are postpartum, 18% are term, and 52% are preterm.

HELLP Syndrome Common presenting complaints are RUQ or

epigastric pain, N/V, malaise or nonspecific symptoms suggesting an acute viral syndrome.

Any patient with these symptoms or signs of preeclampsia should be evaluated with CBC, platelet count, and liver enzymes.

When platelet count < 50,000/mm3 or active bleeding occurs, coagulation studies needed to R/O DIC.

Prevention of Preeclampsia

Routine supplementation with calcium, magnesium, omega-3 fatty acids, or antioxidant vitamins is ineffective.

Calcium reduces the risk of developing preeclampsia in high-risk women and those with low dietary calcium intake.

Low-dose aspirin (75 to 81 mg per day) is effective for women at increased risk of preeclampsia, NNT = 69 ; NNT = 227 to prevent one fetal death.

Low-dose aspirin is effective for women at highest risk

from previous severe preeclampsia, diabetes, chronic hypertension, or renal or autoimmune disease, NNT = 18.

Multiorgan Effects of Preeclamsia Cardiovascular – HTN, increased cardiac

output, increased systemic vascular resistance, hypovolemia

Neurological – Seizures-eclampsia, headache, cerebral edema, hyperreflexia

Pulmonary – Capillary leak, reduced colloid osmotic pressure, pulmonary edema

Multiorgan Effects cont…. Hematologic – Volume contraction, elevated

hematocrit, low platelets, anemia due to hemolysis

Renal – Decreased GFR, increased BUN/creatinine, proteinuria, oliguria, ATN

Fetal – Increased perinatal morbidity, placental abruption, fetal growth restriction, oligohydramnios, fetal distress

Management of Preeclampsia The ultimate cure is DELIVERY. Assess gestational age Assess cervix Fetal well-being Laboratory assessment Rule out severe disease

Gestational HTN at Term

Delivery is always a reasonable option if term

If cervix is unfavorable and maternal disease is mild, expectant management with close observation is possible

Mild Gestational HTN Not at Term Rule out severe disease Conservative management Serial labs Twice weekly visits Antenatal fetal surveillance Outpatient versus inpatient

Indications for Delivery in Preeclampsia Fetal indications

Severe intrauterine growth restriction Nonreassuring fetal surveillance Oligohydramnios

Indications for Delivery in Preeclampsia Maternal indications

Gestational age of 38 weeks or greater Platelet count below 100,000 Progressive deterioration of hepatic or renal

function Suspected placental abruption Persistent severe headache or visual changes Persistent severe epigastric pain, nausea, or

vomiting Eclampsia

Criteria for Treatment

Diastolic BP > 105-110 Systolic BP > 200 Avoid rapid reduction in BP Do not attempt to normalize BP Goal is DBP < 105 not < 90 May precipitate fetal distress

Hypertensive Emergencies

Fetal monitoring IV access IV hydration to maintain urine output > 30 mL

per hour, limit to 100 mL per hour. The reason to treat is maternal, not fetal May require ICU

Characteristics of Severe HTN Crises are associated with hypovolemia Clinical assessment of hydration is inaccurate Unprotected vascular beds are at risk, ie.,

uterine

Key Steps Using Vasodilators

250-500 cc of fluid, IV Avoid multiple doses in rapid succession Allow time for drug to work Maintain LLD position Avoid over treatment

Acute Medical Therapy

Hydralazine Labetalol Nifedipine Nitroprusside Clonidine

Hydralazine

Dose: 5-10 mg every 20 minutes Onset: 10-20 minutes Duration: 3-8 hours Side effects: headache, flushing, tachycardia,

lupus like symptoms Mechanism: peripheral vasodilator

Labetalol

Dose: 20 mg, then 40, then 80 every 20 minutes, for a total of 220mg

Onset: 1-2 minutes Duration: 6-16 hours Side effects: hypotension Mechanism: Alpha and Beta blockade

Nifedipine

Dose: 10 mg po, not sublingual Onset: 5-10 minutes Duration: 4-8 hours Side effects: chest pain, headache,

tachycardia Mechanism: CA channel blockade

Clonidine

Dose: 1 mg po Onset: 10-20 minutes Duration: 4-6 hours Side effects: unpredictable, avoid rapid

withdrawal Mechanism: Alpha agonist, works centrally

Nitroprusside

Dose: 0.2 – 0.8 mg/min IV Onset: 1-2 minutes Duration: 3-5 minutes Side effects: cyanide accumulation,

hypotension Mechanism: direct vasodilator

Seizure Prophylaxis

Magnesium sulfate Loading dose of 4 to 6 g diluted in 100 mL of

normal saline, given IV over 15 to 20 minutes, followed by a continuous infusion of 1-2 g per hour

Monitor urine output, RR and DTR’s With renal dysfunction, may require a lower

dose

Magnesium Sulfate

Is NOT a hypotensive agent Works as a centrally acting anticonvulsant Also blocks neuromuscular conduction Serum levels: 4-7 mg/dL Additional benefit of reducing the incidence of

placental abruption

Toxicity

Respiratory rate < 12 DTR’s not detectable Altered sensorium Urine output < 25-30 cc/hour Antidote: 10 ml of 10% solution of calcium

gluconate 1 g IV over 2 minutes.

Eclampsia New onset of seizures in a woman with pre-

eclampsia. Preceded by increasingly severe preeclampsia,

or it may appear unexpectedly in a patient with minimally elevated blood pressure and no proteinuria.

Blood pressure is only mildly elevated in 30-60% of women who develop eclampsia.

Occurs: Antepartum - 53%, intrapartum - 19%, or postpartum - 28%

Treatment of Eclampsia

Protecting the patient and her airway Place patient on left side and suction to

minimize the risk of aspiration Give oxygen Avoid insertion of airways and padded tongue

blades IV access Mag Sulfate 4-6 g IV bolus, if not effective,

give another 2 g

Alternate Anticonvulsants

Diazepam 5-10 mg IV Sodium Amytal 100 mg IV Pentobarbital 125 mg IV Dilantin 500-1000 mg IV infusion

After the Seizure

Assess maternal labs Fetal well-being Effect delivery Transport when indicated No need for immediate cesarean delivery

Other Complications

Pulmonary edema Oliguria Persistent hypertension DIC

Pulmonary Edema

Fluid overload Reduced colloid osmotic pressure Occurs more commonly following delivery as

colloid oncotic pressure drops further and fluid is mobilized

Treatment of Pulmonary Edema Avoid over-hydration Restrict fluids Lasix 10-20 mg IV Usually no need for albumin or Hetastarch

(Hespan)

Oliguria

25-30 cc per hour is acceptable If less, small fluid boluses of 250-500 cc as

needed Lasix is not necessary Postpartum diuresis is common Persistent oliguria almost never requires a

PA cath

Persistent Hypertension

BP may remain elevated for several days Diastolic BP less than 100 do not require

treatment By definition, preeclampsia resolves by 6

weeks

Disseminated Intravascular Coagulopathy Rarely occurs without abruption Low platelets is not DIC Requires replacement blood products and

delivery

Anesthesia Issues

Continuous lumbar epidural is preferred if platelets normal

Need adequate pre-hydration of 1000 cc Level should always be advanced slowly to

avoid low BP Avoid spinal with severe disease

SORT: KEY RECOMMENDATIONS FOR PRACTICE

In women without end-organ damage, chronic hypertension in pregnancy does not require treatment unless the patient's blood pressure is persistently greater than 150 to 180/100 to 110 mm Hg. – C

Calcium supplementation decreases the incidence of hypertension and preeclampsia, respectively, among all women (NNT = 11 and NNT = 20), women at high risk of hypertensive disorders (NNT = 2 and NNT = 6), and women with low calcium intake (NNT = 6 and NNT = 13). – A

Low-dose aspirin (75 to 81 mg daily) has small to moderate benefits for the prevention of preeclampsia (NNT = 72), preterm delivery (NNT = 74), and fetal death (NNT = 243). The benefit of aspirin is greatest (NNT = 19) for prevention of preeclampsia in women at highest risk (previous severe preeclampsia, diabetes, chronic hypertension, renal disease, or autoimmune disease). – B

For women with mild preeclampsia, delivery is generally not indicated until 37 to 38 weeks of gestation and should occur by 40 weeks. – C

Magnesium sulfate is the treatment of choice for women with preeclampsia to prevent eclamptic seizures (NNT = 100) and placental abruption (NNT = 100). – A

Intravenous labetalol or hydralazine may be used to treat severe hypertension in pregnancy because neither agent has demonstrated superior effectiveness. – B

For managing severe preeclampsia between 24 and 34 weeks of gestation, the data are insufficient to determine whether an "interventionist" approach (i.e., induction or cesarean delivery 12 to 24 hours after corticosteroid administration) is superior to expectant management. Expectant management, with close monitoring of the mother and fetus, reduces neonatal complications and stay in the newborn intensive care nursery. – B

Magnesium sulfate is more effective than diazepam (Valium; NNT = 8) or phenytoin (Dilantin; NNT = 8) in preventing recurrent eclamptic seizures. – A

Quiz1. Which one of the following statements about

preeclampsia is correct? A. Magnesium sulfate is the treatment of choice to prevent eclamptic seizures.

B. Diazepam (Valium) is more effective than magnesium sulfate in preventing recurrent eclamptic seizures.

C. Low-dose aspirin is beneficial for the prevention of preeclampsia in low-risk women.

D. An "interventionist" approach is superior to expectant management for severe preeclampsia between 24 and 34 weeks of gestation.

2. Which of the following agents is/are used to treat a 30-year-old woman (gravida 1, para 0) at 19 weeks of gestation who has had a blood pressure measurement of 160/115 mm Hg on two occasions during her current pregnancy?

A. Methyldopa (Aldomet; brand no longer available in the United States).

B. Nifedipine (Procardia).

C. Labetalol.

D. Lisinopril (Prinivil).

3. Which of the following is/are part of the diagnostic criteria for severe preeclampsia?

A. Blood pressure measurement ≥ 160 mm Hg systolic or 110 mm Hg diastolic on two occasions at least six hours apart.

B. Blood pressure measurement ≥ 150 mm Hg systolic or 100 mm Hg diastolic on two occasions at least six hours apart.

C. Proteinuria ≥ 3 g in a 24-hour urine specimen.

D. Proteinuria ≥ 5 g in a 24-hour urine specimen.

References

Lawrence L, Fontaine P. Hypertensive Disorders in Pregnancy. American Family Physician. July 1, 2008.

Wagner L. Diagnosis and Management of Preeclampsia. American Family Physician. December 15, 2004.

ACOG Committee on Obstetric Practice. ACOG practice bulletin. Diagnosis and management of preeclampsia and eclampsia. No. 33, January 2002. American College of Obstetricians and Gynecologists. Obstet Gynecol 2002;99:159-67.

Report of the National High Blood Pressure Education Program Working Group on High Blood Pressure in Pregnancy. Am J Obstet Gynecol. 2000;183(1):S1-S22.