hypertensive disease pregnancy Flashcards
causes of preexisting hypertension in a young person (if dx in first trimester)
+ what signs / inx can help?
Renal - renal artery stenosis (lsiten for bruit, renal USS) urinalysis Hb /protein, casts, Cr
CKD from GN, polycystic kidney disease
Cardiac - aortic coarctation (look for radiofemoral delay)
Endocrine - hyperparathyroidism (calcium), cushings, conns syndrome, phaeochromocytoma (urinary catecholamines) Low K (hyperaldosteronism / conns)
What are the risks of essential HTN in pregnancy (%)
25% risk of PET
28% PTB
17% IUGR
4% Abruption and death
GHTN
Rate of development to PET
GHTN only 15% develop PET (less the later the onset is)
Severe Complications of PET
Eclampsia - tonic clonic grand mal seizure (only 1/3 have HTN dx in the week before they have an eclamptic seizure - antepartum 45%, intrapartum 18% PN 36%) Stroke Cortical blindness - from posterior reversible encephalopathy syndrome - oedema to the CNS Respiratory distress / pulmonary oedema HELLP DIC Renal failure Hepatic rupture Transient L venticular dysfunction placental - abruption, death, IUGR
PET risk factors
Medical Renal disease, Preexisting HTN OR 3.5 Antiphospholipid syndrome RR 9 Connective tissue disease Sickle cell Diabetes (preexisting or GDM) RR 3.5
Obstetric Primip (2-3X increase) twins (2X) Prev PET (7X) Long interpreg interval (over 10 years) (2-3X) Hydrops / large placenta Molar pregnancy / triploidy
General
over 40
obese
FHX - mother had it - 25% chance, sister 40%
MAP How do you calculate
Mean arterial pressure
D + 1/3 (S-D)
nifedipine
Mode of action
Side effects
Calcium channel blocker
Side affects include flushing, headache, oedema
labetalol
Mode of action
contraindications
Side effects
a and b adrenergic blocker
BD - QID
contraindicated in asthma
ACEi and Angiotensin II receptors
What affects on the fetus in pregnancy
Teratogenic
T1 - cardiovascular and neurological malformations
T2/3 oligohydramnios, renal failure, hypotension, decrease skull ossification, hypocalvaria renal tubular dysgenesis, IUD
Magnesium sulphate dosing
Indications for Mg levels
Signs of overdose
Loading dose 4g diluted in saline over 15-20mins then 1-2g / hour maintenance for 24-48 hours
If seizes again 2-4g IV over 10 mins (recurrence on MgSO4 10%)
IM ok too
If AKI then half maintenance dose
Indications for MgSO4 levels are AKI, liver impairment or oliguric
Side effects - loss deep tendon reflex as neuromuscular blockade, Double vision, slurred speech, respiratory depression and cardiac arrest
Indications for aspirin prophylaxis
Aspirin reduces the risk of PET by 15% but the NNT is 90
From 12 weeks
one major Prev PET T1 or T2 diabetes Chronic HTN Chronic kidney disease Autoimmune disease (SLE, antiphospholipid syndrome) OR more then one moderate risk factor First pregnancy 40 or older Preg interval over 10 years BMI 35+ at first visit Fhx PET Multiple pregnancy
BP treatment thresholds
SOMANZ
Why treat high BPS
Antihypertensives for 160/110
Stat treatment for 170/110
cerebral haemorrhage, posterior reversible encephalopathy syndrome, hypertensive encephalopathy
How to check BP
- position
- sounds
Sitting, feet flat on floor, arm at the level of the heart
Supine should be avoided
in labour - BP maybe measured in lateral recumbency
Correct cuff size - the bladder must cover over 80% of the arm circumference
Sounds
K1 - first sound heard
K4 (muffling - best not to use this)
K5 - Disappearance of the sound completely
rate of deflation <2mm per second
How do you diagnose PET when preexisting Proteinurea or HTN
You cannot use worsening BP or PCR as an indication of PET
You also cannot use SGA as this is independent of PET
You need maternal systemic effects or fetal effects eg oligo, abn dopplers
CLASP study
outcomes
In our multicentre study 9364 women were randomly assigned 60 mg aspirin daily or matching placebo.
Overall, the use of aspirin was associated with a reduction of only 12% in the incidence of proteinuric pre-eclampsia, which was not significant. Nor was there any significant effect on the incidence of IUGR or of stillbirth and neonatal death. Aspirin did, however, significantly reduce the likelihood of preterm delivery (19.7% aspirin vs 22.2% control; absolute reduction of 2.5 [SD 0.9] per 100 women treated; 2p = 0.003). There was a significant trend (p = 0.004) towards progressively greater reductions in proteinuric pre-eclampsia the more preterm the delivery.
CLASP study
inclusion
74% were entered for prophylaxis of pre-eclampsia, 12% for prophylaxis of IUGR, 12% for treatment of pre-eclampsia, and 3% for treatment of IUGR.
CLASP - is there harm to aspirin?
Aspirin was not associated with a significant increase in placental haemorrhages or in bleeding during preparation for epidural anaesthesia, but there was a slight increase in use of blood transfusion after delivery.
CLASP findings
Findings do not support routine prophylactic or therapeutic administration of antiplatelet therapy in pregnancy to all women at increased risk of pre-eclampsia or IUGR.
Non significant reduction in PET
Aspirin did, however, significantly reduce the likelihood of preterm delivery (19.7% aspirin vs 22.2% control; absolute reduction of 2.5 [SD 0.9] per 100 women treated; 2p = 0.003). There was a significant trend (p = 0.004) towards progressively greater reductions in proteinuric pre-eclampsia the more preterm the delivery.
Low-dose aspirin may be justified in women judged to be especially liable to early-onset pre-eclampsia severe enough to need very preterm delivery. In such women it seems appropriate to start low-dose aspirin prophylactically early in the second trimester.
How does aspirin help the placenta?
Aspirin works by irreversibly inhibiting almost all the platelet cyclo oxygenase activity thereby blocking synthesis of the thromboxane - a vasoconstrictor and platelet aggregating agent
Pre pregnancy counselling previous PET
15% risk recurrence (7X increased)
This number is increased if any baseline medical conditions - CKD, HTN, APLS
Higher recurrence if HELLP or early onset PET
Consideration of lifetime cardiovascular disease risk - candidates for screening and possible intervention
PET increases lifetime risk of HTN (3-4X) IHD (2X) and CVS
Indications for aspirin for PET prophylaxis
Major - 1 of these
Major risk factors for pre-eclampsia include:
Previous pre-eclampsia requiring delivery before 37weeks
or
With haemolysis, elevated liver enzymes, and/or low platelets
(HELLP Syndrome)
Predisposing medical conditions
• Autoimmune e.g.
o Systemic Lupus Erythematosus
o Scleroderma
o Anti-phospholipid syndrome
• Chronic hypertension
• Diabetes type 1 and 2
• Any chronic kidney disease
Assisted conception with oocyte donation
Family history of pre-eclampsia (mother and/or sister)
Minor - more then 1
When to take aspirin
At night
best at 12 weeks
evidence best before 16 weeks
can give up to 20 weeks
What are the benefits of calcium
Who gets it ?
The Cochrane review demonstrated that calcium supplementation also reduces the overall
risk of pre-eclampsia, [RR 0.45 (95% CI 0.31 to 0.65); I² = 70%]. As above the effect was
greatest for women with low calcium diets and women at high risk of pre-eclampsia.
Importantly calcium supplementation also reduced the risk of preterm birth [RR 0.76 (95% CI
0.60 to 0.97); I² = 60%], maternal death or serious maternal morbidity [RR 0.80 (95% CI 0.65
to 0.97); I² = 0%].
Calcium did not reduce the rate of SGA infants and should not be
prescribed for prevention of SGA alone.
Aspirin contraindications ?
Contraindications to LDA (rare in women of reproductive age)
• Previous peptic ulcer
• Asthma induced by Non-Steroidal Anti Inflammatory Drugs
• Allergy to aspirin
NNT for aspirin and calcium to prevent PET
NNT for calcium 7
NNT for aspirin 56
what is the harm of high levels of Vit C and E
LBW babies
What BPS need Tx
What BP needs urgent treatment
What are Tx targets
> 160/110
Who needs tx
BPs >140/90
BP targets are 130-150/80-100
Options for tx severe hypertension
160/110
What are their onsets
nifedipine 10 mg oral conventional release
onset of action 30-45 minutes - max effect in 30 minutes
repeat tab after 30-45 minutes
max 80 mg daily
Labatelol
20 mg IV bolus over 2 minutes
onset: 5 minutes
Max effect 10-15 minutes
Repeat every 10 minutes with 40-80mg
Max 300 mg
Hydralazine 5-10 mg IV bolus over 3-10 minutes (5 mg if fetal compromise) onset 20 minutes max effect 10-18 minutes repeat q 20 mins max 30 mg consider crystalloid bolus 200 mg
MgSO4 antidote ?
IV calcium gluconate
Signs of MgSO4 toxicity
– reflexes are absent
– the respiratory rate is less than 12 per minute, or
– the urine output drops below 100 mL in 4 hours.
