HANDLING HYPERTENSIVE CRISIS

IN PREGNANCY

OVERVIEW

Hypertension during pregnancy includes a

number of condition and occurs in 6 - 8% of

all pregnancies. These conditions include

gestational hypertension, pre eclampsia /

eclampsia, and chronic hypertension and are

responsible for considerable maternal and

perinatal morbidity and mortality.

Definitions

Hypertension

Blood pressure taken in the sitting position

(with the right arm horizontal) that is

persistently recorded as being more than

30 mmHg systolic and/or more than

15 mmHg diastolic above pre-pregnancy

or early pregnancy value.

Definitions

In the absence of knowledge of pre-

pregnancy or early pregnancy values,

>140 mmHg systolic and or > 90 mmHg

diastolic (diastolic blood pressure is

recorded with disappearance of the

Korotkoff V sound)

Definitions

Proteinuria

Urine protein that is > 300 mg/24 hours

collection or a spot urine protein : creatinine

ratio > 25 mg/mmol are the two recognised

determinants of proteinuria.

Semi quantification by dipstick testing may

be unreliable

Definitions

Oedema

Oedema is no longer included in the definition

of pre eclampsia as it occurs equally in women

with and without this condition.

CLASSIFICATION OF

HYPERTENSION IN

PREGNANCY

Gestational Hypertension

Development of an elevated blood pressure

after 20 weeks of pregnancy or in the first 24

hours postpartum. No other signs of

symptoms of pre eclampsia or evidence of

hypertensive vascular disease is present.

Resolution of blood pressure elevation occurs

by 12 weeks postpartum.

Pre eclampsia

Mild pre eclampsia

- onset of mild hypertension (an increase of 20

mmHg systolic and or more than 10 mmHg

diastolic)

- proteinuria

- uncomplicated by neurologic symptoms or

criteria for the diagnosis of severe pre

eclampsia

Severe Pre-eclampsia

Diagnosed when

Blood pressure > 170 mmHg systolic and/or

110 mmHg diastolic

The diagnosis should also be considered in

women with lesser degrees of hypertension,

but who have on or more of the following:-

Severe Pre-eclampsia

Severe proteinuria (> 5 gm / 24 hours)

Oliguria (< 400 ml in 24 hours)

CNS dysfunction (severe headache, blurred

vision, changing sensorium)

Thrombocytopenia

Liver disease

Pulmonary oedema

IUGR

Eclampsia

The occurrence of convulsions or coma

(not caused by trauma or coincidental

neurologic disease such as epilepsy) in

woman chose condition also fulfils the

criteria for the diagnosis of pre eclampsia

Defining a Hypertensive Emergency /

Crisis

Is a matter of some debate

Blood pressure above 200/115 mmHg

? above 170/110 mmHg

? Rate of change in blood pressure is

what precipitates the crisis, as opposed

to the absolute blood pressure reading

Pathophysiology of Hypertensive Crisis

The true pathophysiology is obscure

Prominent feature seems to be loss of

cerebrovascular autoregulation, resulting in

hypertensive encephalopathy once the upper

limits of cerebral perfusion pressure are

exceeded

Rapid control of blood pressure is needed

even more because of the risks of placental

abruption and stroke

Minimizing Organ Damage

Most important clinical objective

In non pregnant state: Brain

In obstetric cases: the major morbidity and

mortality result from cardiac and renal, as

well as cerebrovascular damage

Fetal morbidity and mortality is often directly

linked to the maternal condition.

Minimizing Organ Damage

With restoration of acceptable blood

pressures, generally in the range of 140 to

150 mmHg systolic and 90 to 100 mmHg

diastolic, cardiac dysfunction begins to

reverse, renal function tends to improve, and

the restoration of cerebral autoregulatory

lessen the likelihood of stroke

Other Causes

Need to rule out other cause of hypertensive

crisis:-

Frequently, chronic hypertension of severe

pre eclampsia defines the underlying “cause”

of severe hypertension, however other

diagnosis such as uncontrolled

hyperthyroidism or pheochromocytoma,

should not be overlooked.

Regimen to Lower

Blood Pressure Safely

It is imperative that the blood pressure be

lowered in a measured and safe manner, not

to exceed a drop of 25% to 30% in the first

60 minutes, and not to drop below 150/95

mmHg

Too swift or too dramatic a reduction in blood

pressure can have untoward consequences

for both mother and fetus, i.e.

Regimen to Lower

Blood Pressure Safely

Maternal myocardial or cerebral

infarction

Acute fetal distress secondary to

uteroplacental underperfusion

Regimen to Lower

Blood Pressure Safely

Short-acting intravenous agents are

recommended to treat hypertensive

emergencies

Oral or sublingual compound are to be

avoided because they are more likely to

cause precipitous and erratic drop of blood

pressure

Regimen to Lower

Blood Pressure Safely

Pulmonary oedema is not uncommon,

due to capillary leakage and myocardial

dysfunction. Use of frusemide will best

allow for improvement of the clinical

picture in a timely manner

Acute Management Steps

Critical care facilities required

Patient should be cared for in an intensive

care unit (or labour and delivery unit with

critical care capabilities). In most institutions,

such management will include participation of

anesthesiologists, maternal fetal medicine

specialists and nurses with critical care

expertise.

Acute Management Steps

Delivery considerations

During initial management, the patient should

have continuous fetal heart rate monitoring.

It is often not possible to prolonged a

pregnancy that is remote from term.

Delivery decision will need to balance

prematurity risks against maternal risks

of continuing the pregnancy.

Use of Glucocorticoids

Hypertension in not a contraindication to

glucocorticoids for accelerating lung

maturation in the fetus and minimizing

neonatal risk of intracranial hemorrhage and

necrotizing enterocolitis.

Adjusting for gestational age, neonates of

preeclamptic mothers are afforded no

additional maturity compared with neonates

born prematurely for others reasons.

Use of Glucocorticoids

Delay of delivery for 48 to 72 hours may

not be possible in many cases,

however.

Once the patient is stabilized, delivery

must be considered

Drug Therapy

Intravenous fluids (Hartmann’s solution) at

100 -125 ml per hour

5 – 10 mg Hydralazine, given intravenously

as a bolus over 5 – 10 minutes, then by

continuous infusion at 5 mg/hour, with

adjustment of rate every 30 minutes until BP

140/90 mmHg to 160/95 mmHg

Reactive tachycardia with hydralazine may

necessitate use of IV beta blockers

Drug Therapy

The second agent of choice for the acute

treatment of hypertension is oral nifedipine.

Side effect of headache is frequent.

Occasionally hypertension resistant to

hydralazine and nifedipine requires other

drugs eg. Nitroproside or GTN

Drug Therapy

Level 1 evidence indicates that Magnesium

sulphate is the superior drug to use in the

prevention and the treatment of eclamptic

seizures.

The Magpie Trial found the risk of eclampsia

was halved and the risk of placental abruption

and overall maternal deaths were reduced in

women treated with Mg sulphate compared to

a control group.

Drug Therapy

In most cases, however, to exclude a

diagnosis of pre-eclampsia in a timely

manner is nearly impossible, hence

Magnesium sulphate is recommended,

in addition to continue with

antihypertensive to maintain BP control.

Magnesium sulpate Regime

It is best administered intravenously,

preferably through an infusion pump

apparatus. A loading dose of 4 to 6 gm is

given as a 20% solution over 15 to 20

minutes. In a patient with normal renal

function, a rate of 2gm per hour is

appropriate, but may need to be reduced if

acute renal failure ensues.

Delivery Decision

Vaginal delivery in often less

hemodynamically stressful for the mother,

but no always practical.

Many cases are remote from term and non

vertex presentation or uterine cervix is

unfavorable for induction, or a protracted

attempt at labor induction may not be

prudent.

Delivery Decision - cont

Often there is present of some degree

uteroplacental insufficiency. Altered placental

function, combine with extreme prematurity,

often results in the fetus being unable to

tolerate labour for long, necessitating

emergency Caesarean delivery.

The anaesthetist will review the optimal

anaesthesia technique.

Postpartum Management

With the delivery of the fetus, there may be a

temptation to be less rigorous in maintaining

blood pressure control during the post-partum

period.

This may be acceptable in patients with

chronic hypertension, as these patients

better tolerate higher blood pressures and

still maintain appropriate cerebral vascular

autoregulation.

Postpartum Management

For women who were previously normotensive, or who had superimposed preeclampsia, more vigorous control of blood pressure is recommended, especially if they show any degree of thrombocytopenia or pulmonary oedema.

The rationale relates to cerebral perfusion pressures and risk of stroke, and the risks of worsening pulmonary oedema in the setting of increased capillary hydrostatic pressure and reduced colloid osmotic pressure

Postpartum Management

Continuation of Mg sulphate is

recommended for patients with

superimposed pre-eclampsia until

obvious signs of disease resolution, and

for a minimum of 24 hours.

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