Hypertensive disorders Flashcards
uterine ischemia/underperfusion
insufficient blood flow to the uterus
inflammation
excessive maternal inflammatory response to pregnancy
angiogenesis
factors regulating the formation of new blood vessels in the placenta are overproduced –> affect the blood vessel health in the mother leading to hypertension
prostacyclin/thrombaxane imbalance (ASA)
disruption of the balance of hormones that maintain the diameter of the blood vessels
endothelial activation and dysfunction
damage to lining of blood vessels that keep fluid and protein inside
calcium deficiency
helps maintain blood vessels and normal blood pressure
hemodynamic vascular injury
injury to vessels due to excessive blood flow or pressure
immunological activation
Immune system mistakenly responds as if damage has occurred to the blood vessel and in trying to fix the ‘injury’ makes issue worse
preeclampsia
multi-system disorder characterised by hypertension and involvement of one or more organ systems
trigger of preeclampsia
poor placental perfusion due to abnormal placental trophoblastic infiltration of the uterine spiral arteries
secondary pathology (preeclampsia)
reduced blood flow to major organs which causes endothelial damage
pathophysiology (preeclampsia)
decreased blood flow to placenta causes inadequate placental perfusion
RESPONSE = vasoactive substances are released by the hypoperfused placenta, which in turn leads to further widespread endothelial damage and profound vasospasm with a consequent reduction in plasma volume
- Endothelial damage then activates the coagulation cascade and platelets adhere to the sites of endothelial damage
- As a result serious effects present in the mother and fetus
effects preeclampsia
- Abnormal placentation
- CVS and haematological changes
- Coagulation system effects
- Renal involvement
- Liver involvement
- CNS involvement
- Fetoplacental changes
blood pressure
force exerted by the blood on the vessel walls
systolic
pressure exerted on the blood vessel walls following ventricular systole, when the arteries contain the most blood and is the time of maximal pressure
diastolic
pressure exerted on the blood vessel wall during ventricular diastole, when the arteries contain the least amount of blood, resulting in the least pressure being exerted on the blood vessel walls
hormonal and anatomical changes results in…
increase blood volume, increased cardiac output, HR
Bp … first trimester
decreases
rises … from the middle of pregnancy then returns to … levels by term
gradually
pre-pregnant
hypertension in pregnancy
systolic 140mmHg, diastolic 90mmHg
severe hypertension
170
110
risks factors for developing pre-eclampsia
primips
40+
new partner
past history/fam history
multiples
medical conditions
obesity
autoimmune diseases
ART
eclampsia
occurence of seizures in patient with pre-eclampsia
- 1:2000 pregnancies
50 000 women worldwide die
management for eclampsia
pre-conception counselling
risk factors and referral
screening
surveillance
treatment options
own institutional protocols
department of health policies
hospital management
FMAU
admission
low dose aspirin (100mg) cease 36 weeks
fetal management eclampsia
early transfer to tertiary
USS
umbilical artery doppler velocimetry,
amniotic fluid volume estimation
cardiotocography (CTG)
IMI steroids if <34 weeks
medication acute
severe hypertension e.g 170/110mmHg due to risk of intracerebral haemorrhage and eclampsia
acute medications EXAMPLES
if conscious, commence oral antihypertensive therapy: e.g. Oral Nifedipine 10-20mg, onset of action 30-45 minutes.
I.V bolus of Hydralazine: 5mg loading dose and repeat at 20 minute intervals, maximum of 3 doses. Onset 10-20 mins.
MgSO4 infusion: loading dose of 4g over 15-30 mins with maintenance infusion of 1g/hr for at least 24 hours
medications chronic
In cases of mild hypertension for B.P maintenance i.e. if B.P reaches 140-160/90-100mmHg on more than one occasion.
For ongoing treatment, initial drugs of choice: labetalol, oxprenolol, methyldopa, hydralazine, nifedipine, clonidine, prazosin.
Treatment aims at maintaining the diastolic ≤90mmHg
haematological disturbances
- The term HELLP (haemolysis, elevated liver enzymes and low platelets) is a manifestation of severe pre-eclampsia and occurs in 0.6% of all pregnancies
- HELLP is involved in over half of the maternal mortality cases of eclampsia.
- HELLP is often accompanied by S/S of heartburn, vomiting, headache and epigastric pain.
Disseminated intravascular coagulation
- platelet consumption and clotting, that occurs in the placental bed and more widely throughout the circulation, coupled with the anticoagulant effect of fibrin degradation products. This creates a bleeding tendency and organ failure.
- Treat the underlying cause, and practice caution with I.V fluid replacement as overload and pulmonary oedema common. Platelet transfusions, FFP and/or cryoprecipitate may all be used in treatment.
Investigation of new onset hypertension in pregnancy
- Urine dipstick testing for proteinuria, with quantitation by laboratory methods if >’1+’ (30mg/dL)
- Full blood count
- Urea, creatinine, electrolytes
- Liver function tests
- Ultrasound assessment of fetal growth, amniotic fluid volume and umbilical artery Doppler flow
methyldopa (dose, action, contraindication, practice points)
dose - 250-750mg TDS
central action
depression contraindication
Slow onset of action over 24 hr. Dry mouth, sedation, blurred vision
Withdrawal effect with clonidine
labetalol (dose, action, contraindication, practice points)
100-400mg tds
B blocker with mild alpha vasodilator effect
B blocker with ISA
Asthma, chronic airways limitation
Heart block
Bradycardia, bronchospasm, headache, nausea, scalp tingling which usually resolves within 24-48 hours (labetalol only)
nifedipine (dose, action, contraindication, practice points)
20mg bd - 60mg SR bd
Ca channel antagonist
Aortic stensosis
Severe headache associated with flushing, tachycardia Peripheral edema, consipation
prazosin (dose, action, contraindication, practice points)
0.5-5mg TDS
A blocker
flushing, headache, nausea, lupus-like syndrome
hydralazine (dose, action, contraindication, practice points)
25-50mg TDS IV
vasodilator increase cardiac output
Flushing, headache, nausea, lupus-like syndrome
magnesium sulphate
decreases CNS irritability and blocks neuromuscular conduction by blocking the release of acetylcholine at neuromuscular junctions
→ therapeutic administration initial loading dose of 4-6g by IV in 100mL of fluid over 15-20 minutes
