Hypertensive Disorders in Pregnancy Flashcards
Define Hypertension?
Hypertension is defined as a systolic Blood Pressure over 140 or diastolic Blood Pressure over 90 mmHg, measured twice at least 4 hours apart; or >160 systolic or >110 diastolic on one occasion
What are the risk factors for Hypertensive Disorders in pregnancy?(8)
Extremes of age (<20, >35years)
Family history
Nulliparity
Multiple pregnancy
Preexisting diabetes
Preexisting body mass index >35
Previous pre-eclampsia
Gestational trophoblastic disease
What are the HTN disorders in Pregnancy.
Chronic hypertension
Gestational hypertension
Preeclampsia
Preeclampsia superimposed on chronic hypertension
Eclampsia
Define Chronic HTN
Elevated Blood Pressure of greater or equal to 140/90mmHg :
-Occurring before pregnancy
-Before or at 20 weeks of gestation
-Persistence of BPs 12 weeks postnatal
Why are women with high BPs before 20 weeks of pregnancy assumed to have pre existing or essential hypertension?
Because normally BPs fall in the first and second trimester
Define Gestational Hypertension?
New onset of BP ≥140/90 mmHg occurring after 20 weeks gestation, but without evidence of maternal end organ damage and only lasts up to 12 weeks after delivery.
Define Pre-eclampsia?
It is defined as gestational hypertension of at least 140/90 mmHg on two separate occasions measured at least 4 hours apart accompanied by one or more of the following new-onset conditions at or after 20 weeks gestation
What parameters are involved in Pre-eclampsia ?
-significant Proteinuria of at least 300mg in a 24 hour urine collection or at least 1 g/litre (1+ on urine dipstick).
-Maternal organ dysfunction
1.renal insufficiency
2. Liver involvement
3.neurological complications ( seizures, altered mental state, blindness, stroke). 4.Hematological complications i.e. thrombocytopenia, hemolysis.
5.Uteroplacental dysfunction
How is uteroplacental dysfunction noted?
By intrauterine growth restriction
What does Proteinuria in HTN indicate?
It indicates impaired renal function and by inference, impaired placental function with consequent threat to the fetus
Describe the normal physiology of the uteroplacental function.
Trophoblast cells invade the spiral arterioles within the first weeks of pregnancy and replace the smooth muscle of the walls of the vessel, thus converting them into wide bore, low resistance, large capacitance vessels.
How long does it take for the anatomical conversion of the maternal spiral arteries by the trophoblast cells.
2o weeks
By how much does the placental blood flow increase throughout pregnancy?
From 50ml/min in the first trimester to 500-750ml/min at term.
Describe the pathophysiology of pre-eclampsia?
There is an impairment of trophoblast to invade the myometrial segments of the spiral arteries.
Hence, spiral arteries retain some of their pre-pregnancy characteristics of being relatively narrow bore, of low capacitance and high resistance, and resulting in impaired perfusion of the fetoplacental unit.
This leads to the release of proinflammatory proteins that cause endothelial cell dysfunction causing vasoconstriction in different organs, leading to the manifestations of the syndrome
Describe the severe feature of pre-eclampsia.
-Severe hypertension e.g. a systolic blood pressure over 160 mmHg, or diastolic over 110mmHg with at least 2+ proteinuria. OR
-Moderate hypertension of at least 140mmHg systolic and 90 mmHg diastolic associated with any of: severe headache with visual disturbance; epigastric pain; signs of clonus; liver tenderness; platelet count falling to below 100; creatinine >100 mmol/litres; alanine amino transferase rising to above 50 IU/litres
What are the goals for management of Pre-eclampsia?
Management of pre-eclampsia involves treatment of maternal hypertension and close antenatal supervision of the mother and fetus with timely delivery to prevent deterioration of the mother and fetus
What are the maternal complications of Pre-eclampsia?
Eclampsia
HELLP syndrome
Pulmonary oedema
Cerebral haemorrhage
Cortical blindness
DIC
Renal failure
Hepatic rupture
Transient left ventricular systolic or diastolic dysfunction
What are the fetal complications of Pre-eclampsia?
Intrauterine growth restriction
Premature delivery
Abruptio placenta
Intrauterine fetal demise
Define Pre-eclampsia superimposed on Chronic HTN ?
Chronic hypertension with the development of any maternal organ dysfunction consistent with preeclampsia; thrombocytopenia, renal insufficiency, impaired liver function, pulmonary edema, cerebral or visual symptoms.
How is Pre-clampsia superimposed on C.HTN treated?
Same as Pre-eclampsia
What is Eclampsia?
Occurrence of one or more generalized Tonic-clonic seizures in a preeclamptic patient that cannot be attributed to any cause and no past history of seizure disorder.
What investigations are done in pre-eclamptic patients?
Urine dipstick
Full blood count: This may demonstrate a raised haematocrit/Hb (indicating haemoconcentration) and thrombocytopenia which could indicate HELLP syndrome - Hemolysis, Elevated Liver enzymes and Low Platelets.
Urea, creatinine and electrolytes: Uric acid is a particularly sensitive measure of pre-eclampsia and perinatal outcome, but it is only of clinical significance if the levels are increasing or are very high.
Liver function tests to exclude HELLP syndrome
Obstetric USS – EFW, AFI, Umbilical artery dopplers
Which parameter is used in Malawi in place of uric acid? And how is it interpreted?
- GFR
- Because of the increase in GFR during pregnancy, there is an increase in creatinine clearance lowering its levels to 0.9.So GFR greater than 0.9 indicates renal insuffiency.
Describe the findings on an obstetric USS.
EFW-estimated fetal weight which may be reduced due to reduced Uteroplacental circulation
AFI amniotic Fluid Index may be low because some of the amniotic fluid is produced from the Uteroplacental circulation which has been impaired
Umbilical artery Doppler’s shows reduced blood flow . Uteroplacental insufficiency results in increased resistance in the placenta which reduces blood flow in umbilical arteries
What is the normal amniotic fluid index?
5.0 - 25.0 cm
Describe the management of Pre-eclampsia ?
All women with preeclampsia should be hospitalized.
Blood pressure treatment with antihypertensives; nifedipine or intravenous hydralazine and continuous monitoring maintaining the pressures below 140mmHg systolic and diastolic below 90mmHg.
Give magnesium sulphate in women with severe hypertension or hypertension with neurological signs for seizure prophylaxis.
Monitoring for development of organ dysfunction with frequent above investigations.
Women with preeclampsia should be delivered if they have reached 34wks gestation or sooner if they develop any severe features.
Prenatal corticosteroids for fetal lung maturation should be given between 24 and 34 weeks gestation.
Describe the management of Chronic HTN.
Stop contraindicated antihypertensive medications( i.e. diuretics, ACE inhibitors)
Basic labs: FBC, LFT, creatinine and BUN
Urine dipstick for proteinuria and 24hr urine collection if proteinuria is present
Use antihypertensives to maintain blood pressure in the range of 110-140/80-85. Acceptable initial antihypertensives include methyldopa and nifedipine. Hydralazine should be used as second line agent.
Monitor for development of preeclampsia
Assess fetal wellbeing
For women with superimposed pre-eclampsia: superimposed preeclampsia is an indication for delivery. Administer corticosteroids and MgSO4 as indicated.
For women with chronic hypertension and no additional maternal or fetal complications, deliver at 39 weeks gestation.
Whatis the treatment of gestational HTN.
Control of blood pressure with methyldopa or nifedipine to levels of 110-140/80-85mmHg
Monitor for the development of preeclampsia
Monitor fetal growth and wellbeing.
Delivery can be made until 39 weeks provided blood pressure can be controlled, fetal monitoring is reassuring and pre-eclampsia has not developed.
Describe the management of Eclampsia?
Stabilize the patient with ABC approach
Put the patient in left lateral position in bed on the floor to protect them from injury.
Give intravenous hydralazine 5mg every 15minutes with titration upto 10mg as needed to a total dose of 40mg in an hr until Bp <160/110mmHg
If fully conscious,Methyldopa 500mg 8hrly or nifedipine 10-20mg q8 hrly with hydralazine regimen if Bp >160/110mmHg
To prevent more seizures: MgSO4 4g(20ml of 20% solution) IV in 500mL NS over 10min and 5g(10ml of 20% solution) IM in each buttock with 1ml of 2% lignocaine loading dose in same the syringe
If seizures continue after 15min, give another MgSO4 2g(10ml of 50% solution) IV over 5min
If seizures continue or no MgSO4, consider diazepam 10mg IM over 2min - Maintenance dose of diazepam is 40mg in 500ml of NS/ LR
Assess for mode of delivery -assisted vaginal delivery or caesarean section
How is MgSO4 used in eclampsia?What is its MOA?
-As a primary and secondary prophylaxis?
-Cerebral Vasodilator.
What are the side effects of MgSO4?
neuromuscular blockade
loss of tendon reflexes
double vision
slurred speech
Respiratory depression and cardiac arrest.
What is the dose of MgSO4 prophylaxis is given?
Magnesium sulphate is given as a loading dose of 4 g (diluted to 40 mL) over 5–10 minutes, followed by a maintenance infusion of 1 g/hr intravenously or 4g IV slow push, plus 5g in each buttock as a loading dose, then 4g in alternating buttocks 4 hourly
What happens when toxicity is suspected?
stop the infusion immediately and monitor its levels in the blood
Which patients are given MgSO4?
Every patient with Pre-eclampsia with severe features.
When is MgSO4 stopped?
24 hours post delivery or last convulsion; whichever comes last
What is given as prophylaxis for pre-eclampsia and we can it be given?
-Low dose Aspirin
Anytime from 12 weeks
-Vitamin D and Calcium supplements
Can be given anytime during the pregnancy
Who is the prophylaxis for pre-eclampsia given to?
Any of the patients at high risk of developing pre-eclampsia
Previous preeclampsia
High Body Mass Index
Family history
Diabetes
What is the MOA of anti-hypertensives in pregnancy?
Labetalol; a combined alpha and beta blocker
Nifedipine is a calcium channel blocker
a-Methyldopa (a centrally acting a-adrenergic agonist)
Hydralazine-vasodilator
How are anti-hypetensives adminstered? And why is monitoring important?
Go step by step when giving these Antihypertensives. Finish the first maximal dose of one drug before you pass to another drug
Remember to monitor the patient while administering these drugs to avoid BP crushing which has adverse effects to both the mother and the fetus.
Why are ACE inhibitors and diuretics inhibited in pregnancy?
Diuretics may reduce Uteroplacental perfusion
The use of an ACE inhibitor during the second and third trimesters of pregnancy has been associated with a number of serious foetal malformations including oligohydramnios, foetal and neonatal renal failure, bony malformations, limb contractures, pulmonary hypoplasia, prolonged hypotension and neonatal death.
RAPID AND SLOW ACTING SLIDE.
What is the ultimate management for Hypertensive Disorders?
DELIVER THE BABY.
