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Flashcards in Hypertension in Pregnancy Deck (65)
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What are the CV adaptations to pregnancy?

-Inc in CO
-Inc in PR
-Decrease in TPR
Alterations in BP


What causes the decrease in TPR during pregnancy?

-Increased production of vasodilatory substances (e.g. prostacyclin)
-Decreased sensitivity to vasopressors e.g. angiotensin II


How does BP change throughout pregnancy?

Mid gestation fall in BP with BP returning to early pregnancy levels by the end of gestation


What are appropriate positions for BP measurement during pregnancy? Why?

-Left lateral
-Semi prone
Compression of IVC or aorta by gravid uterus leading to artifactually high or low readings.


Why is it suggested dBP be recorded at Korotkoff IV (muffling) rather than V (cessation) during pregnancy?

Hyperdynamic circulation means pulsations may sometimes be heard down to 0mmHg. Most people still recommend K5.


What is HTN in pregnancy defined as?

Greater than or equal to 140/90mmHg or an increase over the pre/early pregnancy baseline reading of 25/15mmHg +.


Why is 170/11mmHg a significant BP level?

Irreversible vascular damage (e.g. CVA) by BP of this level. Anything above this needs prompt anti-hypertensive therapy.


What are the two broad categories of hypertenion in pregnancy?

-Pregnancy induced HTN (PIH) / pre eclampsia
-Pregnancy associated HTN


What are examples of pregnancy associated hypertension?

-Essential HTN
-Cushing's syndrome
-HTN renal disease
-Coarctation of the aorta
-Collagen diseases
-Carcinoid syndrome


What is the pattern of pregnancy induced hypertension?

Appears in latter half of gestation, resolves following delivery


What is pre-eclampsia?

-Proteinuria (greater than 300mg per 24h)
-Generalised oedema


What is the incidence of pre-eclampsia?

5-10% of pregnancies


What is the incidence of severe pre eclampsia and how is it defined?

1% of pregnanacies:
-PIH >170/110
-Persistent proteinuria
-Generalised oedema


What is the hypothesised mechanisms for pre eclampsia?

Postulated genetic defect suggests dysfunction in normal maternal immunological adaptation to present of foreign antigenic load; leads to immunologically mediated dysfunction (possible too few "blocking" antibodies to foetus) so conceptus exposed to mother's immune material.


How is pre eclampsia represented in placental histology?

Deficient placentation with
-failure of trophoblast invasion of maternal placental bed spiral arteries and
-placental bed vascular artherosis
Leads to impaired placental flow and release of disordered factors leading to maternal endothelial cell dysfunction


How does the balance of vasodilator/constrictor substances change in pre eclampsia?

-reduced vasodilator
-increased vasoconstrictor


What is the hypothesised mechanism of proteinuria?

Postulated immunodysfunction leading to cross reacting autoantibody formation impacting on sites like the renal glomerulus producing proteinuria


What causes oedema of PE?

Increased capillary permeability


What are the clinical manifestations of organ and system dysfunctions?

-Generalised oedema
-Fetal intrauterine growth retardation
-Visual disturbances
-Abodminal pain
-Grand mal convulsions


What are the causes of serious morbidity and mortality resulting from PE?

-Cardiac failure
-Pulmonary oedema
-Renal failure
-Adrenal haemorrhage
-Hepatic failure


What are the histological lesions of PE?

-Spiral artery atherosis in placental bed
-Glomerular endotheliosis on renal biopsy (pathognomonic)


Which conditions increase incidence of PE?

Conditions increasing antigenic load:
-multiple pregnancy
-molar pregnancy
-hydrops foetalis complicated pregnancies


What are the RFx for PE?

-Extremes of reproductive age
-New paternity in previously uncomplicated pregnancy Hx
-PHx chronic HTN
-Chronic renal disease
-auto antibody d/os (SLE, APA)


What are the maternal investigations for PE?

-MSU (proteinuria often due to contamination)
-24h urine protein
-Creatinine clearance estimation
-serum urate concentration
-FBE (haemolysis, coagulopathy)
-LFTs (HELLP syndrome)
May need to exclude other causes e.g. phaeo


How does uric acid relate to pre eclampsia and renal function?

Decrease in renal uric acid clearance with consequent increase in serum levels is an early sign of renal dysfunction in PE


Foetal investigations in PE?

-Umbilical arterial blood flow waveform analysis by Doppler
-US for growth


Mx PE?

-Admit (day to HDU depending on severity): rest, observation, further assessment
- q4h BP, urinalysis
-Anti HTN BP>140/90
-If severe, CVC for CVP monitoring and fluid / Rx titration


what is the only PE cure?

Emptying uterus of foetus, placenta and membranes


What are the anti-HTN of choice in PE?

-PO methyl dopa ongoing
-IV hydrazine when prompt reduction required
Other inc labetolol, nifedipine, diazoxide


What should be given if hyperreflexia or visual disturbance are present?

Prophylactic anti convulsant therapy: magnesium sulfate preferred agent