Download Hypertension in pregnancy

Pregnancy
Induced
Hypertension
Jun Ma
Dept. of Obstetrics & Gynecology
The First Hospital of Xi’an Jiaotong Univ
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
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, > 6h apart
Classification
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
Classification (1)
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 (>300mg/24-hr urine collection) or +
Epigastric discomfort
Thrombocytopenia
Classification (2)
【severe】

BP ≥ 160/110 mmHg

Marked proteinuria (>1-2 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
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
Classification (4)
2. 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
Classification (5)
3. 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.
Classification (6)
4.
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
High risk factors

Nulliparous

<18ys or >40 ys, multiple pregnancy

Has previous gestational hypertensive
disorders

Chronic nephritis

Diabetic

Malnutrition

Low social status

Hydatidiform mole
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
Pathophysiology
Central nervous system

Raised BP disrupt autoregulation

Increased permeability due to vasospasm--thrombosis 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)
Eyes
 Serous
retinal detachment
 Cortical blindness
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
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,
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
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
Blood (1)
Volume: reduced plasma volume
 Normal physiologic volume expansion
does not occur
 Generalized vasoconstriction and capillary
leak
 Hematocrit

Blood (2): coagulation

Isolated thrombocytopenia: <150,000/ml

Microangiopathic hemolytic anemia

DIC (5%)

HELLP syndrome: in severe preeclampsia
1.
schistocytes on the peripheral blood smear
2.
lactic dehydrogenase > 600 u/L
3.
total bilirubin > 1.2 mg/dl
4.
aspartate aminotransferase >70 U/L
5.
platelet count <100,000/mm3

Misdiagnosis: hepatitis, gallbladder disease, ITP
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
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
Clinical findings (1)
Symptoms and signs
1. Hypertension
Diastolic pressure ≥ 90 mmHg or
Systolic pressure ≥ 140 mmHg or
Increase of 30/15 mmHg
2. Proteinuria

>300 mg/24-hr urine collection or

+ or more on dipstick of a random urine
Clinical findings (2)
3. 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
Clinical findings (3)
4.
Differing clinical picture in preeclampsiaeclampsia crises: patient may present with

Eclamptic seizures

Liver dysfunction and IUGR

Pulmonary edema

Abruptio placenta

Renal failure

Ascites and anasarca
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 > 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
Clinical findings (5)
Laboratory findings (2)
Retinal check:
Other tests: ECG, placenta function,
fetal maturity, cerebral angiography,
etc
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
Complications

Preterm delivery

Fetal risks: acute and chronic
uteroplacental insufficiency

Intrapartum fetal distress or stillbirth

IUGR

Oligohydramnios
Predictive evaluation (1)
1. Mean arterial pressure, MAP= (sys.
Bp + 2 x Dia. Bp) /3
 MAP> 85 mmHg: suggestive of
eclampsia
 MAP > 140 mmHg: high likelihood of
seizure and maternal mortality and
morbidity
Predictive evaluation (2)
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: > 20 mmHg
3. Urine calcium/ creatinine < 0.04
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.
Treatment
A.








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
A. Mild preeclampsia: bed rest & delivery
Observe for danger signals: severe
headache, epigastric pain, visual
disturbances
 Sedatives: debatable

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 > 36 wk or if there is evidence of fetal lung
maturity or fetal jeopardy.
Magnesium sulfate
1. Decreases the amount of
acetylcholine released at the
neuromuscular junction
2. Blocks calcium entry into neurons
3. Vasodilates the smaller-diameter
intracranial vessels
Magnesium sulfate
1. Prevent convulsion
2. Virtually ineffective on blood pressure
3. i.v. or i.m.
 5g loading dose 5-10 min, i.v.
 1-2g/hr constant infusion
 Total dose: 20-30 g/d
Toxicity:
 Diminished or loss of patellar reflex
 Diminished respiration
 Muscle paralysis
 Blurred speech
 Cardiac arrest
How to prevent toxicity?

Frequent evaluation of patellar reflex and
respirations

Maintenance of urine output at >25 ml/hr
or 600 ml/d

Reversal of toxicity:
1. Slow i.v . 10% calcium gloconate
2. Oxygen supplementation
3. Cardiorespiratory support
Antihypertensive therapy:
reduce the Dia. pressure to 90-110 mmHg
Indication

Bp> 160/110 mmHg

Dia. Bp > 110 mmHg

MAP > 140 mmHg

Chronic hypertension with previous
antihypertensive drugs usage
Antihypertensive therapy
Medications:

Hydrolazine: initial choice

Labetolol

Nifedipine

Nimoldipine

Methyldoe

Sodium nitroprusside
Mechanism
of action
Effects
hydralazine
Direct peripheral
vasodilation
CO, RBF maternal flushing,
headache, tachycardia
labetalol
a, b- adrenergic
blocker
CO, RBF maternal flushing,
headache, neonatal
depressed respirations
Medication
CO, RBF maternal
orthostatic hypotension
Headache, no neonatal
effects
nifedipine
Calcium channel
blocker
methyldopa
Direct peripheral
CO, RBF maternal flushing,
arteriolar vasodilation headache, tachycardia
sodium nitroprusside
Direct peripheral
vasodilation
Metabolite (cyanide)
toxic to fetus
Plasma expander
 Diuretics

Delivery

Indication of termination of pregnancy
1. Preeclampsia close to term
2. <34 wk with decreased placental
function
3. 2 hs after control of seizure
Delivery

Induction of labor
1.
First stage: close monitor, rest and sedation
2.
Second stage: shorten as much as possible
3.
Third stage: postpartum hemorrhage

Cesarean section
1.
Induction of labor unsuccessful
2.
Induction of labor not possible
3.
Maternal or fetal status is worsening
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
Management
Control of seizure
 Control of hypertension
 Delivery
 Proper nursing care
