Download Questions and Answers about Hypertension in Pregnancy

Hypertension in Pregnancy
for Postgraduates
Max Brinsmead MB BS PhD
January 2016
This talk
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How to measure BP
When is a pregnant woman hypertensive
What is the Differential Diagnosis
What tests are required and how do you
interpret them
Tests for proteinuria
Risk factors for pre-eclampsia
Pathophysiology of pre eclampsia
How to manage the hypertensive gravida
Which is the best drug to lower BP
This talk(2)
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Who should be delivered? How & Where
Best practice intrapartum care
Who requires an anticonvulsant?
What is the best drug for Eclampsia?
Best practice postpartum care
Best practice anaesthetic care
Prognosis after pre-eclampsia
Can pre-eclampsia be predicted?
Can pre-eclampsia be prevented?
How to Measure BP in a Pregnant Woman
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Automated machines not recommended
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Unless calibrated against a mercury sphygmomanometer in
the individual patient
Appropriate sized cuff
Seated for 2 - 3 minutes with feet supported
Both arms first visit
Palpate systolic and go 20 mm higher
Deflate slowly 2 mm every sec
Use Korotkoff 5 (or 4 if 5 absent) for diastolic
Repeated measures may be required
Ambulatory monitoring useful for White Coat
Hypertension
When is a Pregnant Woman
Hypertensive?
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>140/90 on >one occasion
(Rise of >30 systolic or >15 diastolic)
Knowledge of prior BP very important
 Not in itself diagnostic – look for other problems
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Severe hypertension is >169 systolic and
or diastolic >109
 Requires
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admission and urgent Rx
However, the diagnosis is more important
than the actual level of BP.
Differential Diagnosis of Hypertension
in Pregnancy
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Gestational Hypertension
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Preeclampsia
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Sustained hypertension after 20w of pregnancy without any
other organ involvement. Returns to normal in 3m
Sustained hypertension after 20w of pregnancy with
evidence of other organ involvement. Returns to normal in
3m
Chronic Hypertension
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Hypertensive before 20w. 95% is Essential Hypertension
Includes “White Coat Hypertension”
Systems involved in Preeclampsia
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Renal
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Hepatic
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Eclampsia or stroke
Hyperreflexia with sustained clonus
Severe headache or visual disturbance
Cardiovascular
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Thrombocytopenia (<100)
Haemolysis
DIC
CNS
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Elevated transaminases (AST or ALT >70)
Epigastric or RUQ pain
Haematological
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Significant proteinuria (>300 mg in 24 hours or P:C > 0.30)
S Creat >90
Oliguria
Pulmonary oedema
Placental
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IUGR
Abruption
Please note
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I have not used the words “Pregnancy induced
Hypertension” or PIH
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No mention is made of oedema
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Proteinuria is the most common manifestation of
“other system involvement” and some method of
assessment is critical to good obstetric care
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Evidence for other organ involvement in Pre
eclampsia is a mix of symptoms, signs and tests
Tests of Proteinuria
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The screening test is by dipstick
Have a sensitivity >90% using ≥ 1+
 But correlate poorly with high protein loss
 And false negative rates up to 20%
 Will miss >300 mg/24 hours in up to 1:8 patients
 And the test strips spoil quickly in humidity
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Boiling urine is sensitive and quantifiable
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But messy and disliked by midwives
24 hour collection and quantification by lab
Is the gold standard
 But labour intensive and slow
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The protein:creatinine ratio on a spot sample is a
good compromise
Proteinuria in Practice
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Significant proteinuria occurs when...
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is ≥ 2+ on dipstick
 Trace or 1+ should be regarded as equivocal
The 24 hour urine collection is > 300 mg
 The spot urine protein:creatinine ratio is ≥
30 mg/mmol
 There is > “cloud” on boiled urine
 When significant proteinuria has been
detected there is little point in repeating
the measure
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Some rare causes of preeclampsia
before 20w
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Hydatidiform mole
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Fetal triploidy (with or without partial mole)
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Severe renal disease
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Lupus obstetric syndrome
Renal Disease in Pregnancy
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Responsible for about 5% of chronic hypertension
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Causes include:
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chronic or recurrent infection
glomerulonephritis
renal artery stenosis
Must be assessed by creatinine clearance (CC)
which doubles in normal pregnancy
When CC falls below 50% the prognosis is very
bad
Monitoring for superimposed pre eclampsia can
be difficult if there is chronic proteinuria
Donors of a kidney have 2.4-fold increased risk
of PE but usually not severe
Some rare causes of hypertension
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Coarctation of the aorta
 Sometimes
the clue is to measure BP in both arms
 There is a systolic murmur that can be heard in the
back
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Phaeochromocytoma
 Paroxysms
of symptomatic hypertension
 The clue to diagnosis is to think of it
 Associated with high levels of catecholamines
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Hyperaldosteronism
 Also
known as Conn’s disease
Pathophysiology of Pre eclampsia
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Placental tissue
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healthy pregnancies cytotrophoblast
infiltrates the decidual portion of the uterine
spiral arteries
 In order to increase maternal blood flow to the
placenta
 In patients destined to develop pre eclampsia
this fails to occur
 This results in placental hypoperfusion
 These changes occur at <16 weeks gestation
but the pre eclampsia may not be manifest until
much later in the pregnancy
Pathophysiology of Pre eclampsia
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Hypoperfusion
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of the Placenta
Becomes worse as pregnancy progresses
The abnormal uterine vasculature is unable to
accommodate the normal rise in blood flow to
the fetus/placenta that occurs with increasing
gestational age.
Late placental changes consistent with
ischemia include atherosis (lipid-laden cells in
the wall arterioles), fibrinoid necrosis,
thrombosis, sclerotic narrowing of arterioles,
and placental infarction
Pathophysiology WHY?
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An ‘immunolgical’ response to pregnancy
---in ‘at risk’ or predisposed women
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A response to a conceptus whose genetic
material is 50% foreign (from the father)
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A failure of ‘Blocking Antibody’
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This disease is still a mystery
Pathophysiology WHAT?
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Contracted intravascular volume of mother
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reality a failure to increase plasma volume
↑Sensitivity to pressure agents
 Leaky Capillaries
 Reduced oncotic pressure
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part due to low serum albumen
Poor placental reserve
A
fetus at risk of hypoxia and death
Pathophysiology WHAT?
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Hypertension/ Proteinuria/ oedema
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Low platelets
Raised urate
Raised Haematocrit
Haemolysis
Abnormal LFT’s
Abnormal clotting
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Consumption
Cell (DNA) death
Reduced plasma volume
Widespread DIC
Tests for the Hypertensive Gravida
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Blood tests
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Urine Tests
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FBC - look at HB, Haematocrit and Platelets
UEC - look at Creatinine Should be < 0.07 (or 70)
URATE - equivalent to weeks gestation
Liver enzymes – AST & ALT should be <70. Ignore ALP
UMCS - exclude UTI and look for casts
Protein:Creatinine ratio from spot test >30 significant
24 hr protein excretion >300 mg/day significant
Assess fetal welfare by CTG & Scan for AFI
and UA Dopplers
Frequency of Testing
Management of Hypertensive
Gravida
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Hospitalise if pre-eclamptic
Discharge if “just BP”
Bed rest only when there is proteinuria
Control BP to protect mother from severe
hypertension
Role of antihypertensive agents for mild &
moderate chronic hypertension is
controversial
Delivery will cure pre eclampsia & gestational
hypertension
Remember thromboprophylaxis
Tests of Fetal Welfare
Which Drug is Best for
Hypertension in Pregnancy?
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The drug that you know best
Aldomet
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Labetalol
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Up to 480 mg/day
Nifedipine
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Up to 1200 mg/day
Oxyprenalol
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Up to 2250 mg per day
Up to 120 mg/day
Prazosin
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Up to 15 mg/day
Drugs for Hypertension in
Pregnancy?
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Combination therapy of drugs from
different classes is possible e.g.
 Aldomet
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+ Beta blocker + Prazosin
Do not use…
diuretics – reduce plasma volume
 Highly selective beta blokers – cause IUGR
 ACE inhibitors – may cause IUFD
 Thiazide
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Aim for BP 130 -150 systolic and 80 –
100 diastolic
Which Drug is Best for Acute
Hypertension?
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The drug that you know best
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IV Hydralazine 5 – 10 mg every 20-30 min
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IV Labetalol 20 – 50 mg over 2 min.
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Repeat after 15 – 30 min
Nifedipine crushed oral 10 mg
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or by infusion
Repeat after 30 min
IV Diazoxide 15 – 45 mg bolus
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Repeat after 5 min to a maximum of 300 mg
Which Drug is Best for Eclampsia?
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First aid is more important than drugs
Protect from injury
 Secure an airway
 Administer oxygen
 Then secure IV access
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IV MgSO4 4G over 10 – 15 min
Then 1 -2 G/hour by infusion
If seizure recurs then give another 2 – 4 G
bolus
IV Diazepam only for status eclampticus
Monitor urine output, respirations, O2
saturation and DTJ’s
Who Needs Fluid Expansion?
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If there is severe proteinuria and oliguria
Then give 500 – 1000 ml cautiously
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Injudicious use carries a risk of pulmonary oedema and
adult RDS
Pre load prior to epidural or spinal
Consult with anaesthetist
 Use colloids rather than crystalloids
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Sometimes required if BP drops suddenly
Sometimes occurs with Diazoxide/Hydralazine
 CTG monitoring desirable
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Abruption requires prompt resuscitation
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Often requires blood
Watch urine output and/or JVP
Who Requires Delivery?
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Pre eclampsia >36 completed weeks
Uncontrollable hypertension
Deteriorating renal, hepatic or haematologic
state
For GA >32w and good neonatal facilities
delay only long enough to give steroids
Eclampsia or imminently eclamptic
Fetus is compromised
APH - abruption
Induction of Labour vs Expectant Management for
Gestational Hypertension Koopmans et al Lancet 2009
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The HYPITAT study
A multicentre RCT of 756 women in Netherlands
Were 36 – 41 weeks with a diagnosis of mild pre
eclampsia or gestational hypertension
Of the women randomised to induction of labour
31% had a poor outcome vs 44% for observation
(RR=0.71, CI 0.59-0.86, p<0.001)
Poor outcomes included eclampsia, HELLP, severe
pre eclampsia and PPH
No greater risk of Caesarean or neonatal morbidity
Active management is also more cost effective
How to Deliver
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Deliver vaginally if >37w and Cx is favourable
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can be ripened
Caesarean only if the above not met
Elective CS usually at gestations <35w
Inappropriate attempts at delivery when it is
not indicated is an invitation to CS (and more
CS)
Deliver in an environment that can cope with
a severe multisystem disease
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Don’t overlook patient’s and family’s psychological needs
Intrapartum Care
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Assess convulsive risk and consider
prophylactic MgSO4
Control BP with an epidural or IV Hydralazine
Careful fluid balance
Monitor the fetus
Avoid ergometrine
SVD is not a sin!
Anaesthetic Implications
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Epidural good for both vaginal & abdominal
delivery
Spinal + Vasopressin also okay
Spinal plus epidural for a few cases
Low dose aspirin okay for epidural
GA for acute fetal compromise or low
platelets
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<50, and 50 – 75 is a grey zone
Watch for hypertension during GA intubation
Use antacid and lateral tilt
Cautious use of oxytocin boluses
Postpartum Care
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Things may get worse before they get
better
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Seizure risk is greatest for 48 hrs
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Continue MgSO4 infusion for 24 hrs
Avoid NSAIDs
Treat any BP >150/100
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Oliguria for 24 hours is common
Use Nifedipine PRN
OK to discharge 3d after BP control
Follow up weekly to 6w then 3m
The Prognosis after Pre eclampsia
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Mild pre eclampsia near term has a low
recurrence risk
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Unless there is a new partner or a long gap to the next
pregnancy
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Severe pre eclampsia prior to 34w has a 5066% recurrence risk
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Most recover by 12w but these patients are at
increased lifetime risk of hypertension and
related disease
Can Preeclampsia be predicted
and prevented?
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Identifying the patient at risk
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Early pregnancy testing
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Prevention strategies
 Especially
the role of low dose aspirin
Risk factors for severe pre eclampsia
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Previous pre eclampsia at <35w
Renal disease
Thombophilias
Autoimmune disease e.g. SLE
Diabetes
Multiple pregnancy
Severe alloimmunisation
Family history of pre eclampsia
Obesity
Increasing maternal age
Patients at risk
Prediction of Pre eclampsia
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Response to an infusion of angiotensin
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Suitable only in a research setting
Measure vasoactive proteins in serum
PAPP-A, Placental growth factor (PlGF)
 Ratio of soluble tyrosine kinase to PIGF has a high
negative predictive value (99.3%)
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Doppler studies at 12 – 14w
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Placental resistance & Uterine artery pulsatility
Together these last two can identify 90% of
women who will get PE before 34w
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With false positive rate of 10%
The prevention of pre eclampsia
with low dose Aspirin – WHO?
History of fetal death or severe IUGR
 Patients who previously required delivery
for pre eclampsia prior to 34w
 Conditions with high risk of pre eclampsia
eg Lupus or homozygous for thrombophilia
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 These
patients also require heparin
Patients identified by Screening at 12 –
14w (London FMF program)
 Also use Ca supplements of 1.5G daily
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The prevention of pre eclampsia
with low dose Aspirin - Results
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Meta analysis suggests that 100 – 150 mg
daily started BEFORE 16 w
 Reduces
risk of early onset pre-eclampsia by 50 –
90%
 Less valuable if started after 16w
 You need to treat 4-5 women to prevent one FDIU
or severe IUGR
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RISKS
 Does
not increase the risk of APH, PPH or fetal
intracranial haemoorhage
 It is also not teratogenic
Other measures to prevent
preeclampsia
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Anti oxidant supplements (Vitamins C, E)
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Folic acid and multivitamins
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Requires more RCTs
Metformin
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Increase the risk of stillbirth and IUGR. Trials stopped
Improves uteroplacental circulation and reduces the rate
of pre eclampsia and pre term birth for PCO patients who
take it in early pregnancy. Needs study in a wider group of
patients
Abdominal decompression
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Unproven and abandonded
For the NICE Guideline go
to
http://pathways.nice.org.uk/pathways/hyperten
sion-in-pregnancy
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