Hypertension in Pregnancy

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Hypertension in Pregnancy
Lianne Beck, MD Assistant Professor Emory Family
Medicine
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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

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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

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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

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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.

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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.

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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.

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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

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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

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Risk Factors
FACTOR RISK RATIO
Renal disease 201
Chronic hypertension 101
Antiphospholipid syndrome 101
Family history of PIH 51
Twin gestation 41
Nulliparity 31
Age gt 40 31
Diabetes mellitus 21
African American 1.51
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Diagnostic Criteria for Preeclampsia

• 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
• 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 lt 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.

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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.

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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 lt 50,000/mm3 or active
  bleeding occurs, coagulation studies needed to
  R/O DIC.

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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.

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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

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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

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Management of Preeclampsia

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

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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

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Mild Gestational HTN Not at Term

• Rule out severe disease
• Conservative management
• Serial labs
• Twice weekly visits
• Antenatal fetal surveillance
• Outpatient versus inpatient

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Indications for Delivery in Preeclampsia

• Fetal indications
• Severe intrauterine growth restriction
• Nonreassuring fetal surveillance
• Oligohydramnios

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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

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Criteria for Treatment

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

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Hypertensive Emergencies

• Fetal monitoring
• IV access
• IV hydration to maintain urine output gt 30 mL per
  hour, limit to 100 mL per hour.
• The reason to treat is maternal, not fetal
• May require ICU

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Characteristics of Severe HTN

• Crises are associated with hypovolemia
• Clinical assessment of hydration is inaccurate
• Unprotected vascular beds are at risk, ie.,
  uterine

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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

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Acute Medical Therapy

• Hydralazine
• Labetalol
• Nifedipine
• Nitroprusside
• Clonidine

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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

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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

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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

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Clonidine

• Dose 1 mg po
• Onset 10-20 minutes
• Duration 4-6 hours
• Side effects unpredictable, avoid rapid
  withdrawal
• Mechanism Alpha agonist, works centrally

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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

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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 DTRs
• With renal dysfunction, may require a lower dose

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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

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Toxicity

• Respiratory rate lt 12
• DTRs not detectable
• Altered sensorium
• Urine output lt 25-30 cc/hour
• Antidote 10 ml of 10 solution of calcium
  gluconate 1 g IV over 2 minutes.

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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

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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

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Alternate Anticonvulsants

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

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After the Seizure

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

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Other Complications

• Pulmonary edema
• Oliguria
• Persistent hypertension
• DIC

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Pulmonary Edema

• Fluid overload
• Reduced colloid osmotic pressure
• Occurs more commonly following delivery as
  colloid oncotic pressure drops further and fluid
  is mobilized

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Treatment of Pulmonary Edema

• Avoid over-hydration
• Restrict fluids
• Lasix 10-20 mg IV
• Usually no need for albumin or Hetastarch (Hespan)

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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

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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

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Disseminated Intravascular Coagulopathy

• Rarely occurs without abruption
• Low platelets is not DIC
• Requires replacement blood products and delivery

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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

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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

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• 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

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• 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

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• 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

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Quiz

• 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.

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• 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).

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• 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.

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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 200299159-67.
• Report of the National High Blood Pressure
  Education Program Working Group on High Blood
  Pressure in Pregnancy. Am J Obstet Gynecol.
  2000183(1)S1-S22.