Pregnancy Induced Hypertension

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Pregnancy Induced Hypertension

• Jun Ma
• Dept. of Obstetrics Gynecology
• The First Hospital of Xian Jiaotong Univ

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Introduction

• Incidence China 9.4, worldwide 7-12
• The most common and yet serious conditions seen
  in obstetrics
• cause substantial morbidity and mortality in the
  mother and fetus
• Death due to cerebral hemorrhage, aspiration
  pneumonia, hypoxic encephalophathy,
  thromboembolism, hepatic rupture, renal failure

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Hypertension in pregnancy

• Definition
• Diastolic BP 90 mmHg
• Systolic BP 140 mmHg
• Or as an increase in the diastolic BP of 15
  mmHg or in the systolic blood pressure of 30
  mmHg, as compared to previous pressure
• The increased blood pressures be present on at
  least two separate occasions, gt 6h apart

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Classification
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Classification of Hypertensive Disorders in
Pregnancy (ACOG)

• Pregnancy-induced hypertension
• Preeclampsia
• Mild
• Severe
• Eclampsia
• Chronic hypertension preceding pregnancy
• Chronic hypertension with superimposed PIH
• Superimposed preeclampsia
• Superimposed eclampsia
• Gestational hypertension

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Classification (1)

• Pregnancy-induced hypertension
• Hypertension associated with proteinuria and
  edema, occurring primarily in nulliparas after
  the 20th week or near term.
• Preeclampsia
• ?mild ?
• BP 140/90mmHg
• Onset after 20 weeks gestation
• Proteinuria (gt300mg/24-hr urine collection) or
• Epigastric discomfort
• Thrombocytopenia

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Classification (2)

• ?severe?
• BP 160/110 mmHg
• Marked proteinuria (gt1-2 g/24-hr urine collection
  or 2 or more), oliguria
• Cerabral or visual disturbances such as headache
  and scotomata
• Pulmonary edema or cyanosis
• Epigastric or right upper quadrant pain (probably
  caused by subcapsular hepatic hemorrhage)
• Evidence of hepatic dysfunction, or
  thrombocytopenia

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Classification (3)

• Eclampsia
• Meets the criteria of preeclampsia
• Presence of convulsions, not attributable to
  other neurological disease,
• Occurrence 0.5 -4 , with 25 occurring in the
  1st 72 hs postpartum

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Classification (4)

• Chronic hypertension proceeding pregnancy
  (essential or secondary to renal disease,
  endocrine disease, or other causes)
• BP 140/90 mmHg
• Presents before 20 wk gestation
• Persists beyond 12 wk postpartum

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Classification (5)

• Chronic hypertension with superimposed
  preeclampsia or eclamptia
• Coexistence of preeclampsia or eclampsia with
  preexisting chronic hypertension
• Cause greatest risk
• When diagnosis is obscure, it is always wise to
  assume that the findings represent preeclampsia
  and treat accordingly.

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Classification (6)

• Gestational hypertension not mentioned in the
  ACOG
• Finding of hypertension in late pregnancy in the
  absence of other findings suggestive or
  preeclampsia
• Transient hypertension of pregnancy
• May develop into chronic hypertension if elevated
  BP persists beyond 12 weeks postpartum

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High risk factors

• Nulliparous
• lt18ys or gt40 ys, multiple pregnancy
• Has previous gestational hypertensive disorders
• Chronic nephritis
• Diabetic
• Malnutrition
• Low social status
• Hydatidiform mole

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Etiology UNCLEAR

• Immune mechanism (rejection phenomenon,
  insufficient blocking Ab)
• Injury of vascular endothelium----disruption of
  the equilibrium between vasoconstriction and
  vasodilatation, imbalance between PGI and TXA
• Compromised placenta profusion
• Genetic factor
• Dietary factors nutrition deficiency
• Insulin resistance
• Increase CNS irritability

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Pathophysiology
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Central nervous system

• Raised BP disrupt autoregulation
• Increased permeability due to vasospasm---thrombos
  is of arterioles, microinfarcts, and petechial
  hemorrhage
• Cerebral edema increased intracranial pressure
• CT scan (1/3-1/2 positive) focal hypodensity
• Cerebral angiography diffuse arterial
  vasoconstriction
• EEG nonspecific abnormality (75 in eclamptic
  patient)

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Eyes

• Serous retinal detachment
• Cortical blindness

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Pulmonary system

• Pulmonary edema
• Cardiogenic or noncardiogenic
• Excessive fluid retention, decreased hepatic
  synthesis of albumin, decreased plasma colloid
  oncotic pressure,
• Often occurs postpartum
• Aspiration of gastric contents the most dreaded
  complications of eclamptic seizures

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Kidneys

• Characteristic lesion of preeclampsia
  glomeruloendotheliosis
• Swelling of the glomerular capillary endothelium
• Decreased GFR
• Fibrin split products deposit on basement
  membrane
• Proteinuria
• Increase of plasma uric acid, creatinine,

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Liver

• The spectrum of liver disease in preeclampsia is
  broad
• Subclinical involvement
• Rupture of the liver or hepatic infarction
• HELLP syndrome hemolysis, elevated liver enzymes
  and low platelets

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Cardiovascular system

• Generalized vasoconstriction, low-output,
  high-resistance state
• Untreated preeclamptic women are significantly
  volume-depleted
• Capillary leak
• Cardiac ischemia, hemorrhage, infarction, heart
  failure
• Increased sensitivity to vasoconstrictor effects
  of angiotensin

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Blood (1)

• Volume reduced plasma volume
• Normal physiologic volume expansion does not
  occur
• Generalized vasoconstriction and capillary leak
• Hematocrit

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Blood (2) coagulation

• Isolated thrombocytopenia lt150,000/ml
• Microangiopathic hemolytic anemia
• DIC (5)
• HELLP syndrome in severe preeclampsia
• schistocytes on the peripheral blood smear
• lactic dehydrogenase gt 600 u/L
• total bilirubin gt 1.2 mg/dl
• aspartate aminotransferase gt70 U/L
• platelet count lt100,000/mm3
• Misdiagnosis hepatitis, gallbladder disease, ITP

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Endocrine system

• Vascular sensitivity to catecholamines and other
  endogenous vasopressors such as antidiuretic
  hormone and angiotensin II is increased in
  preeclampsia
• Disequilibrium of prostacyclin/ thromboxane A2

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Placenta perfusion

• 500 mm vs 200 mm
• Acute atherosis of spiral arteries fibrinoid
  necrosis of the arterial wall, the presence of
  lipid and lipophages and a mononuclear cell
  infiltrate around the damaged vessel----vessel
  obliteration---- placental infarction
• Fetus is subjected to poor intervillous blood
  flow
• IUGR or stillbirth

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Clinical findings (1)

• Symptoms and signs
• Hypertension
• Diastolic pressure 90 mmHg or
• Systolic pressure 140 mmHg or
• Increase of 30/15 mmHg
• Proteinuria
• gt300 mg/24-hr urine collection or
• or more on dipstick of a random urine

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Clinical findings (2)

• Edema
• Weight gain 1-2 lb/wk or 5 lb/wk is considered
  worrisome
• Degree of edema
• Preeclampsia may occur in women with no edema
• Most recent reports omit it from the definition

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Clinical findings (3)

• Differing clinical picture in preeclampsia-eclamps
  ia crises patient may present with
• Eclamptic seizures
• Liver dysfunction and IUGR
• Pulmonary edema
• Abruptio placenta
• Renal failure
• Ascites and anasarca

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Clinical findings (4)

• Laboratory findings (1)
• Blood test elevated Hb or Hct, in severe cases,
  anemia secondary to hemolysis, thrombocytopenia,
  FDP increase, decreased coagulation factors
• Urine analysis proteinuria and hyaline cast,
  specific gravity gt 1.020
• Liver function ALT and AST increase, alkaline
  phosphatase increase, LDH increase, serum albumin
• Renal function uric acid 6 mg/dl, serum
  creatinine may be elevated

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Clinical findings (5)

• Laboratory findings (2)
• Retinal check
• Other tests ECG, placenta function, fetal
  maturity, cerebral angiography, etc

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Differential diagnosis

• Pregnancy complicated with chronic nephritis
• Eclampsia should be distinguished from epilepsy,
  encephalitis, brain tumor, anomalies and rupture
  of cerebral vessel, hypoglycemia shock, diabetic
  hyperosmatic coma

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Complications

• Preterm delivery
• Fetal risks acute and chronic uteroplacental
  insufficiency
• Intrapartum fetal distress or stillbirth
• IUGR
• Oligohydramnios

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Predictive evaluation (1)

• Mean arterial pressure, MAP (sys. Bp 2 x Dia.
  Bp) /3
• MAPgt 85 mmHg suggestive of eclampsia
• MAP gt 140 mmHg high likelihood of seizure and
  maternal mortality and morbidity

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Predictive evaluation (2)

• Roll over test ROT
• Preeclamptic patients are more sensitive to
  angiotensin II
• Difference between Bp obtained at left recumbent
  position and supine position (at a 5 min
  interval)
• Positive gt 20 mmHg
• Urine calcium/ creatinine lt 0.04

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Prevention

• Calcium supplementation not effective in low
  risk women bur show effect in high risk group
• Aspirin (antithrombotic) uncertain
• Good prenatal care and regular visits
• Baseline test for high-risk women
• Eclampsia cannot always be prevented, it may
  occur suddenly and without warning.

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Treatment

• Mild preeclampsia bed rest delivery
• Hospitalization or home regimen
• Bed rest (position and why) and daily weighing
• Daily urine dipstick measurements of proteinuria
• Blood pressure monitoring
• Fetal heart rate testing
• Periodic 24-h urine collection
• Ultrasound
• Liver function, renal function, coagulation

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A. Mild preeclampsia bed rest delivery

• Observe for danger signals severe headache,
  epigastric pain, visual disturbances
• Sedatives debatable

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B. Severe preeclampsia

• Prevention of convulsion magnesium sulfate or
  diazepam and phenytoin
• Control of maternal blood pressure
  antihypertensive therapy
• Initiation of delivery the definitive mode of
  therapy if severe preeclampsia develops at or gt
  36 wk or if there is evidence of fetal lung
  maturity or fetal jeopardy.

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Magnesium sulfate

• Decreases the amount of acetylcholine released at
  the neuromuscular junction
• Blocks calcium entry into neurons
• Vasodilates the smaller-diameter intracranial
  vessels

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Magnesium sulfate

• Prevent convulsion
• Virtually ineffective on blood pressure
• i.v. or i.m.
• 5g loading dose 5-10 min, i.v.
• 1-2g/hr constant infusion
• Total dose 20-30 g/d

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• Toxicity
• Diminished or loss of patellar reflex
• Diminished respiration
• Muscle paralysis
• Blurred speech
• Cardiac arrest

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• How to prevent toxicity?
• Frequent evaluation of patellar reflex and
  respirations
• Maintenance of urine output at gt25 ml/hr or 600
  ml/d
• Reversal of toxicity
• Slow i.v . 10 calcium gloconate
• Oxygen supplementation
• Cardiorespiratory support

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Antihypertensive therapy reduce the Dia.
pressure to 90-110 mmHg

• Indication
• Bpgt 160/110 mmHg
• Dia. Bp gt 110 mmHg
• MAP gt 140 mmHg
• Chronic hypertension with previous
  antihypertensive drugs usage

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Antihypertensive therapy

• Medications
• Hydrolazine initial choice
• Labetolol
• Nifedipine
• Nimoldipine
• Methyldoe
• Sodium nitroprusside

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Mechanism of action
Effects
Medication
Direct peripheral vasodilation
CO, RBF maternal flushing, headache, tachycardia
hydralazine
CO, RBF maternal flushing, headache, neonatal
depressed respirations
a, b- adrenergic blocker
labetalol
CO, RBF maternal orthostatic hypotension Headache,
no neonatal effects
Calcium channel blocker
nifedipine
Direct peripheral arteriolar vasodilation
CO, RBF maternal flushing, headache, tachycardia
methyldopa
Metabolite (cyanide) toxic to fetus
sodium nitroprusside
Direct peripheral vasodilation
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• Plasma expander
• Diuretics

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Delivery

• Indication of termination of pregnancy
• Preeclampsia close to term
• lt34 wk with decreased placental function
• 2 hs after control of seizure

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Delivery

• Induction of labor
• First stage close monitor, rest and sedation
• Second stage shorten as much as possible
• Third stage postpartum hemorrhage
• Cesarean section
• Induction of labor unsuccessful
• Induction of labor not possible
• Maternal or fetal status is worsening

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Eclampsia

• No aura preceding seizure
• Multiple tonic-clonic seizures
• Unconsciousness
• Hyperventilation after seizure
• Tongue biting, broken bones, head trauma and
  aspiration, pulmonary edema and retinal detachment

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Management

• Control of seizure
• Control of hypertension
• Delivery
• Proper nursing care