Hypertension in pregnancy Flashcards
Describe the changes in blood pressure in pregnancy
¥ Blood pressure (BP) proportional to systemic vascular resistance and cardiac output
¥ Pregnancy Vasodilatation
¥ BP falls in early pregnancy
¥ Nadir reached at 22-24 weeks (lowest point)
¥ Steady rise until Term
¥ BP falls after delivery but subsequently rises and peaks at day 3-4 P/N
what is the classification of hypertension in pregnancy?
¥ ≥140/90 mmHg on 2 occasions
¥ Diastolic BP >110 mmHg
¥ ACOG - >30/15 mmHg compared to booking BP
What 3 different ways can hypertension present in pregnancy?
- pre-existing hypertension
- pregnancy induced hypertension
- Pre-eclampsia
Pre-existing hypertension:
- what is this?
- what is important to consider?
- what does this increase the risk of?
This is:
- HTN at booking or <20wks
- HTN >3mths of delivery
Consider:
-secondary causes e.g. renal/cardiac, cushing’s, conn’s, phaeochromocytoma
Risks:
- PET
- IUGR
- Abruption
What is pregnancy induced hypertension?
New hypertension > 20wks without signif. Proteinuria and resolves within 6months of delivery
¥ No proteinuria or other features of pre-eclampsia
¥ Better outcomes than pre-eclampsia
¥ 15% progression to pre-eclampsia - depends on gestation
¥ Rate of recurrence is high
What is pre-eclampsia? what are the three criteria?
This is a pregnancy-specific multi-system disorder with unpredictabl, variable and widespread manifestations
- Hypertension
- Proteinuria (≥0.3g/l or ≥0.3g/24h)
- Oedema
what is the pathogenesis of pre-eclampsia?
¥ Genetic predisposition
¥ Stage 1 - abnormal placental perfusion
¥ Stage 2 - maternal syndrome
¥ Abnormal placentation and trophoblast invasion failure of normal vascular remodelling
¥ Spiral arteries fail to adapt to become high capacitance, low resistance vessels
¥ Placental ischaemia widespread endothelial damage and dysfunction
¥ Mechanism unclear (??oxidative stress / PGI2 : TXA2 imbalance / NO)
¥ inc. Endothelial Activation
¥ inc. Capillary Permeability
¥ inc. Expression of CAM
¥ inc. Prothrombotic Factors
¥ inc. Platelet aggregration
VASOCONSTRICTION
How does Pre eclampsia effects the CNS? 6
¥ Eclampsia ¥ Hypertensive encephalopathy ¥ Intracranial haemorrhage ¥ Cerebral Oedema ¥ Cortical Blindness ¥ Cranial Nerve Palsy
How does Pre eclampsia affect the renal system?
¥ GFR
¥ Proteinuria
¥ serum uric acid (also placental ischaemia)
¥ creatinine / potassium / urea
¥ Oliguria /anuria
¥ Acute renal failure
- acute tubular necrosis
- renal cortical necrosis
How does Pre eclampsia affect the liver?
¥ Epigastric/ RUQ pain
¥ Abnormal liver enzymes
¥ Hepatic capsule rupture
¥ HELLP Syndrome
Haemolysis, Elevated Liver Enzymes, Low Platelets
(microvascular endothelial activation and cell injury)
¥ high morbidity/ mortality
How does Pre eclampsia affect the haematological system?
¥ decreased `Plasma Volume ¥ Haemo-concentration ¥ Thrombocytopenia ¥ Haemolysis Disseminated Intravascular Coagulation
How does Pre eclampsia cause cardi/pulmonary disease?
¥ Pulmonary oedema leads to ARDS ¥ iatrogenic ¥ disorder related ¥ Pulmonary Embolus High mortality
What can the placental disease of Pre eclampsia lead to?
- Intrauterine growth restriction
- Placental abruption
- Intrauterine death
What are the symptoms of pre-eclampsia? 6
¥ Headache ¥ Visual disturbance ¥ Epigastric / RUQ pain ¥ Nausea / vomiting ¥ Rapidly progressive oedema ¥ Considerable variation in timing, progression and order of symptoms
What are the signs seen in pre-eclampsia? 8
¥ Hypertension ¥ Proteinuria ¥ Oedema ¥ Abdominal tenderness ¥ Disorientation ¥ SGA ¥ IUD ¥ Hyper-reflexia / involuntary movements / clonus
What investigations are carried out for Pre eclampsia ? 10
¥ Urea & Electrolytes ¥ Serum Urate ¥ Liver Function Tests ¥ Full Blood Count ¥ Coagulation Screen ¥ UPCR ¥ CTG ¥ Ultrasound - biometry, ¥ AFI, Doppler
What are the risk factors for Pre eclampsia ?
¥ Maternal Age (>40 years 2X) ¥ Maternal BMI (>30 2X) ¥ Family History (20-25% if mother affected, up to 40% if sister) ¥ Parity (first pregnancy 2-3X) ¥ Multiple pregnancy (Twins 2X) ¥ Previous PET (7X) ¥ Molar Pregnancy / Triploidy ¥ medical risk factors (Multiparous women develop more severe disease)
What are the medical risk factors for Pre eclampsia ? 5
¥ Pre-existing renal disease ¥ Pre-existing hypertension ¥ Diabetes Mellitus ¥ Connective Tissue Disease ¥ Thrombophilias (congenital / acquired)
How is Pre eclampsia screened for/assessed at the booking appointment?
¥ Assess risk at booking – risk factors for pre-eclampsia = aspirin
¥ Then surveillance (scans/BP monitoring/urine testing)
¥ Hypertension < 20 weeks - look for secondary cause
Antenatal screening – BP/urine
How is Pre eclampsia managed antenatally?
¥ Treat hypertension
¥ Follow ups in MDAU PIH can be managed as o/p in day care unit
How is Pre eclampsia managed in labour?
¥ Maternal & fetal surveillance
¥ Timing of Delivery – most deliver at 37 weeks vaginally if pre-eclampsia
¥ Stabilize, treat hypertensions, prevent convulsions, deliver
When is a woman with pre-eclampsia referred to the antenatal day care unit? 4
- BP 140/90 or more
- (++)proteinuria
- oedema
- symptoms - esp persistent headache
When is a woman admitted for Pre eclampsia ? 6
- BP >170/110 OR >140/90 with (++) proteinuria
- Significant symptoms - headache / visual disturbance / abdominal pain
- Abnormal biochemistry
- Significant proteinuria - UPCR >30mg/mmol
- Need for antihypertensive therapy
- Signs of fetal compromise
What is involved with inpatient assessment of Pre eclampsia ?
¥ Blood Pressure - 4 hourly ¥ Urinalysis - daily ¥ Input / output fluid balance chart ¥ UPCR - if proteinuria on urinalysis ¥ Bloods - FBC, U&Es, Urate, LFTs. Minimum X2 per week
What is involved with fetal surveillance in Pre eclampsia ?
¥ Fetal Movements ¥ CTG - daily ¥ Ultrasound -Biometry -Amniotic Fluid Index -Umbilical Artery Doppler
When is hypertension treated in pregnancy?
Treat regardless of aetiology
With MAP ≥150 mmHg there is significant risk of cerebral haemorrhage:
¥ Most treat if BP ≥150/100 mmHg (aim for <150/80-100 BP)
¥ If target organ damage aim for BP <140/90
¥ If less than 140/90 or 130/90 – reduce dose
¥ BP ≥ 170/110 mmHg requires immediate Rx
(Control of blood pressure does not reduce the risk of developing pre-eclampsia)
What does every woman with pre-eclampsia recieve?
magnesium sulphate to prevent siezures
What 4 drugs are used for hypertension in pregnancy?
- Methyldopa
- labetalol
- nifedipine SR
- Hydralazine
Methyldopa:
- mode of action
- starting dose
- max. dose
- contraindication
- breast feed?
mode of action:
-centrally acting alpha agonist
Starting dose:
-250mg BD
max. dose:
- 1gram TDS
Contraindication:
-depression
breast feed?
-YES
Labetalol oral or IV:
- mode of action
- starting dose
- max. dose
- contraindication
- breast feed?
Mode action:
-alpha and beta blocker
Starting dose:
-100mg BD
Max dose:
-600mg qid
contraindications:
-asthma
Breastfeed:
yes
Nifedipine SR oral :
- mode of action
- starting dose
- max. dose
- contraindication
- breast feed?
mode of action:
-Ca channel blocker
- starting dose:
- 10mg BD
- max. dose:
- 40mg BD
- contraindication:
- none
-breast feed?
yes
Hydralazine IV:
- mode of action
- starting dose
- max. dose
- contraindication
- breast feed?
Action:
-vasodilator
Starting dose:
-25mg tds
Max dose:
-75mg QID
Contrai. - none
Breast feed:
-yes
What anti-HTN drugs are avoided in pregnancy?
Diuretics/ACE-I
When is the baby delivered in pre-eclampsia?
¥ The only cure for pre-eclampsia is delivery
¥ Mother must be stabilised before delivery
¥ Consider expectant management if pre-term
¥ Most women delivered within 2 weeks of diagnosis
What are 6 indications for delivery?
¥ Term gestation ¥ Inability to control BP ¥ Rapidly deteriorating biochemistry / haematology ¥ Eclampsia ¥ Other Crisis ¥ Fetal Compromise - REDF, abnormal CTG
What crisis exists in pre-eclampsia? 9
¥ Eclampsia ¥ HELLP syndrome ¥ Pulmonary Oedema ¥ Placental Abruption ¥ Cerebral Haemorrhage ¥ Cortical Blindness ¥ DIC ¥ Acute Renal Failure ¥ Hepatic Rupture
What is eclampsia?
Tonic-clonic (grand mal) seizure occuring with features of pre-eclampsia
¥ >1/3 will have seizure before onset of hypertension / proteinuria
¥ Ante-partum (38%) / Intra-partum (16%) / post-partum (44%)
¥ More common in teenagers
¥ Associated with ischaemia / vasospasm
What is the management of severe PET or eclampsia?
¥ Control BP: IV labetalol/IV hydralazine
¥ Stop / Prevent Seizures
¥ Fluid Balance
¥ Delivery
Describe the prevention of siezures in PET?
Magnesium sulfate:
Loading dose: 4g IV over 5 minutes
Maintenance dose:IV infusion 1g/h
If further seizures administer 2g Mg SO4
If persistent seizures consider diazepam 10mg IV
Describe fluid balance in PET?
¥ Main cause of death = pulmonary oedema
(Capillary leak / fluid overload / cardiac failure)
¥ Oliguria in 30%. Does not require intervention
¥ Any doubts about renal function urine osmolality
¥ Fluid challenges are potentially dangerous
¥ Safer to run a patient “dry” - 80 ml/
Delivery in PET:
- aim for what delivery?
- what is used for anaesthesia
- what is used to monitor baby?
- what is avoided and cautioned?
¥ Aim for vaginal delivery if possible ¥ Control BP ¥ Epidural anaesthesia ¥ Continuous electronic fetal monitoring ¥ Avoid ergometrine ¥ Caution with iv fluids
When is low dose aspirin used in the prevention of PET?
¥ Aspirin - inhibits cyclo-oxygenase prevents TXA2 synthesis
¥ 75mg Aspirin 15% reduction in PET (NNT=90)
¥ May be more beneficial in preventing severe early onset pre-eclampsia (MRC CLASP Trial)
¥ Safe
¥ Used for high risk women - Renal, DM, APS, Multiple risk factors, previous PET
¥ Commence before 12 weeks (NICE Aug 2010)