Q.1. Why
antihypertensives in pregnancy period? Antihypertensive therapy is used to
protect the mother from ill effects of
severe hypertension such as A)
cerebrovascular hemorrhage B) cardiac failure C) abruption and D) eclampsia. But one should
make it clear that the value of antihypertensives in mild moderate
disease in unclear because ,maternal
death and stroke is rare and eclampsia is unusual in these women with essential hypertension. By that I
don’t mean that you should not prescribe antihypertensives in esn HTN in preg
women ,.But we have to be judicious as I am quoting below.
. Q.2.
Should we use antihypertensive drugs at
all in mild hypertension ? Unfortunately
drug treatment for mild preeclampsia has been disappointing
as shown by the Cochrane review
which concluded that treatment induced decrease in blood pressure may
adversely affect fetal growth.
Q.3. At what BP we should initiate
antihypertensives if not startd
already?? The
risk benefit profile in mild to
moderate disease needs to be re
examined and my dear members may I draw
your kind attention that ACOG recommends
anti hypertensives only when diastolic blood pressure is 105-110 mm Hg or higher although many clinicians
start anti hypertensives at diastolic
blood pressure of 100 or higher.
Q.4: What is
the aim then ? What is the message to practicing Obstetricians then? There is consensus that
antihypertensives should be prescribed when systolic blood pressure is > 160 mm Hg or diastolic blood pressure
is > 110 mm Hg
Q.12:-When
Methyldopa becomes as first line ?? Where an adrenoceptor antagonist is
contraindicated methyldopa is used as first line therapy.
Q.12: Which agent shpoluld never be
used? ACE inhibitors must not be used antetatally especially
during second and third
trimester. Reported complications with ACE inhibitors include contractures persistent PDA pulmonary
hypoplasia respiratory distress syndrome
prolonged neonatal hypertension and
neonatal death.
Methyldopa (a2 Adrenergic agonists central inhibition of sympathetic drive )
–Dosage – 250 -500 mg po q6-12 h – Max
dose 4 g/ 24h -- benefits – Proven to
be safe , and efficacious decreased
second trimester fetal losses – Adverse
effects – Maternal fatigue depression orthostatic hypotension xerostomia
elevated liver enzymes
Nifedipine ( calcium channel
blocker inhibits extracellular
calcium influex into cells through slow calcium channels )—Dosage 10-20 mg
oral q4-6 hour –Max Dose 240 mg /24h –Benefits –Effective for
refractory HTN Potent tocolysis in
preterm labor lowers BP without
effects on blood flow in the umbilical artery –Adverse effects –
Maternal effects flushing headache
palpitations interaction with magnesium sulfate profound hypotension no increase risk of
congenital malformations
Labetalol (a and B) blocker reduction in cardiac output
) Dosage 100 mg po bid Max dose
2400 mg/ 24 hour - Benfits - Effective BP control lowers BP without
altering cerebral autoregulation lower risk of arrhythmia than with vasodilatory agents , Adverse effects – Fetal bradycardia nenonatal
hypoglycemia impaired fetal
response to hypoxia decreased
uteroplacental flow avoid in
patients with asthma and CHF.
Oral or intravenous
therapy can be decided on the basis of the
presentation . hypertensive crisis can be classified as:
Hypertensive urgency
which is defined as severely elevated blood pressure is responsible for signs symptoms or
laboratory evidence of end organ damage. Rapid but controlled reduction in
BP intravenous medication
is required. One should target to reduce MABP by 25% within hour of
presentation . If initial
reduction is well tolerated
reduction to normal levels can be achieved over ensuing 24 hours.
The objective of treating acute severe hypertension is to
prevent potential cerebrovascular and
cardiovascular complications such as encephalopathy hemorrhage by some for sustained systolic BP values of at least 180mmHg and for
sustained diastolic values of at least
110 mm Hg The definition of sustained hypertension is not clear ranging
from 30 mm to 2 hours . Others use mean arterial pressure to guide management. Antihypertensive therapy
should be initiated urgently if mean arterial pressure is more than 140 mm Hg as above this cerebral auto regulation of pressure is not reliable. Agents used for treatment of acute severe hypertension should be initiated at low doses given that
women with preeclampsia are
intravascular volume depleted and are at
increased risk for hypotension. A latest
review has generated uncertainty about the agent of first choice among them bur
labetalol and nifedipine are usually preferred as compared to hydralazine which is associated with more adverse
outcomes.
What are the therapeutic options in the treatment of acute severe hypertension
Labetalol Onset of action – 5 min , Dosage- 20 mg iv bolus
then 40 mg after 10 min then 80 mg every
10 min upto a maximum total dose
of 220 mg a continuous infusion of 1-2
mg/ min may also be used ,
Nifedipine –onset of
action – 10 min ,Dosage- 10mg po can be repeated in 30 min then 10-20 mg q4 -6h
with a maximum dose of 240 mg/24 hours
Nitroglycerine –onset
of action, dosage – Initial infusion rate of 10 mg/ min and titrated to the desired pressure by
doubling the dose very five minutes
, Adverse effects – Methemoglobinemia
may result from high dose iv infusion
Hydralazine –onset of
action – 10-20 min , Dosage- 5-10 mg iv
every 15-20 min until a desired response
is obtained , Adverse effects – Profound maternal hypotension and
Oliguria fetal distress . Maternal pyridoxine responsive polyneuropathy and
drug induced lupus neonatal thrombocytopenia and lupus
Sodium nitroprusside – onset of action 0.5 to5 min ,
dosage – 0.2 -5 ug /kg/ min infusion for use in refractory hypertension ,
adverse effects – Fetal cyanide and
thiocyanate toxicity
The blood pressure and pulse rate should be monitored every 5
min and the goal of therapy is to
decrease the diastolic BP to 90-100 mm
Hg.
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