Hypertensive Disorders of Pregnancy PDF

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Summary

Pre-eclampsiaNormal BP in Pregnancy BP depends on cardiac output and systemic vascular resistance  BP normally falls to a minimum level during the middle of the 2 nd trimester o By about 30/15 mmHg o Due to about 50% reduction in SVR  Occurs in both normotensive & chronic hypertensive wom...

Description

Pre-eclampsia Normal BP in Pregnancy  BP depends on cardiac output and systemic vascular resistance  BP normally falls to a minimum level during the middle of the 2nd trimester o By about 30/15 mmHg o Due to about 50% reduction in SVR  BP = CO x SVR  Occurs in both normotensive & chronic hypertensive women  CO = SV x HR  At term  BP rises to pre-pregnant levels  BP = SV x HR x SVR Hypertension due to pre-eclampsia  Due to  in systemic vascular resistance   in Protein excretion in normal pregnancy HOWEVER it is still 140/90 mmHg AFTER 20 weeks Due to either o Pre-eclampsia o Transient HTN / gestational HTN Resolves after delivery NOT associated with proteinuria o Usually diagnosed retrospectively when proteinuria does not occur BP > 140/90 mmHg o On at least 2 occasions o 4 hours apart BP > 170/110 mmHg o One occasion AFTER 20 weeks Associated with new onset proteinuria o >0.3 g/24 hours Often with oedema Eclampsia / epileptiform seizures  most dramatic complication Proteinuria may be absent o Especially in early disease o Difficult to differentiate from gestational diabetes

Chronic Hypertension

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BP >140/90 mmHg o BEFORE pregnancy o BEFORE 20 weeks o Woman already on antihypertensive medication Primary or secondary HTN (due to renal disease) o May be existing proteinuria due to renal disease 6x  risk of ‘superimposed pre-eclampsia’ in those with chronic / pre-existing HTN

Proteinuria  > 0.3 g/24 hours  Overall risk of progressing to pre-eclampsia with proteinuria  15-20% o Depends on gestation at which HTN develops 1. 2. 3. 4.

40 years previous pregnancy 3. Pregnancy interval >10 years 2. Chronic kidney disease 4. BMI >35 at booking (2-3x) 3. Autoimmune disease 5. Family Hx of o SLE / APL syndrome o Pre-eclampsia (3x) 4. Type I/II DM o TII DM (1.5x) 5. Chronic HTN o HTN (2x) 6. Multiple pregnancy (3x) 7. Ethnicity 8. Previous SGA baby (30mg/nmol 24-hour collection

>0.3 g/24 hours

HELLP Syndrome 1. Haemolysis o Dark urine o Raised lactic dehydrogenase o Anaemia 2. Elevated Liver enzymes o Epigastric pain o Liver failure o Abnormal clotting 3. Low Platelets o Normally self-limiting

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Seldom significant Possible significant proteinuria  quantify Significant proteinuria likely  quantify Confirmed significant proteinuria Confirmed significant proteinuria

Clinical Evaluation 1. History o Pre-eclampsia is usually asymptomatic + raised BP + proteinuria o Following can occur at late stages  Headache  Drowsiness  Worsening peripheral / periorbital oedema  Nausea / vomiting  Epigastric pain (RUQ) + PV bleeding with abruption  CVA / Seizures / confusion 2. Examination o HTN usually the first sign  Occasionally absent until late stages o Oedema  Found in most pregnancies  Massive in pre-eclampsia  Not postural or of sudden onset  Not diagnostic  NO facial, oedema o Symphysis-Fundus Height  Restricted foetal growth o Foetal heart rate o Tenderness over liver  Impending sign of complications o Clonus   3 beats  Associated with cerebral irritation Maternal Complications  Early onset more severe  Occurrence of any complications (can occur together)  indication for delivery  regardless of gestation  May also occur post-partum  takes 24 hours for disease to be cured 1. Eclampsia o PET (pre-eclamptic toxaemia) complicated with convulsions / fits o Grand mal seizures o Probably result of cerebrovascular vasospasm o Mortality from hypoxia + concomitant complications of severe disease Treatment  magnesium sulphate + intensive surveillance for other complications 2. Chronic hypertension o Risk of developing chronic HTN after delivery 3. Cerebrovascular haemorrhage o Results from failure of cerebrovascular blood flow autoregulation at MAP >140 mmHg 5

Treatment  anti-hypertensive medication 4. Liver & coagulation problems o HELLP syndrome o DIC o Liver failure / liver rupture  Typically experiences epigastric pain  may be presenting complaint  Haemolysis turns the urine dark Treatment  magnesium sulphate prophylaxis to prevent eclampsia 5. Renal Disease o Identified by careful fluid balance monitoring & creatinine measurements Treatment  haemodialysis in severe cases 6. Pulmonary oedema o Seen in severe pre-eclampsia o Due to fluid overload Treatment  oxygen + furosemide o Assisted ventilation may be requires o ARDS can develop Foetal Complications  Perinatal mortality & morbidity are increased o 5% of stillbirths o 10% of pre-term deliveries 

Early onset o Growth restriction o Pre-term delivery often required o Spontaneous pre-term labour is common

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At term o Affects foetal growth less o Increased morbidity & mortality o Increased risk of placental abruption

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Investigations Confirm diagnosis 1. Bedside dipstick o Quantify protein 2. 24-hour collection OR 3. Protein – creatinine ratio (PCR) 0.3 g/24 hours = 30 mg/mmol 

Repeat test for protein as may be absent in early disease

Maternal complications 1. U&E o  creatinine = severe complications / renal failure o  uric acid o Renal function often mildly impaired 2. FBC o  haemoglobin o Rapid  in platelet aggregation on damaged endothelium indicated impending HELLP 3. LFTs o  ALT = liver damage / impeding HELLP 4. LDH levels o  with liver disease / haemolysis

Foetal complications 1. USS o Weight o Foetal growth 2. Umbilical artery Doppler + CTG o Foetal wellbeing 3. Short term variability (STV) o From computerise d CTG o Best form of daily analysis

Antenatal Screening 1. Blood pressure 2. Urinalysis o Dipstick  Significant if 1+ o 24-hour analysis  >0.3 g/24 hours  >0,5 g/24 hours  adverse maternal + foetal outcomes o Urine PCR

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Early predication  Uterine artery Doppler  20 weeks o Not routinely used  Integration of uterine doppler scan with BP and risk factors o Higher sensitivity  Sensitivity figures are better for early onset pre-eclampsia Later predication  Ratio of sFlt-1 to PlGF in maternal blood in later pregnancy with mild hypertension  Useful in determining who will develop pre-eclampsia Prevention  Low dose aspirin (75mg) o Starting before 16 weeks o Preferable in the evening o Modestly reduces risk of pre-eclampsia  High dose vitamin with calcium supplement o May help reduce risk

Management Assessment  Women with BP >140/90 are assessed in the day unit o BP rechecked + other investigations  sFlt-1 and PlGF ratio o may determine who is at the highest risk  Patients without proteinuria & mild HTN (30 OR >0.3 g/24 j hour urine collection 3. Severe HTN o BP > 160/110 mmHg 4. Growth restriction with abnormal umbilical artery Doppler OR abnormal CTG 5. Abnormal sFlt-1 / PlGF assay

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Drugs in Pre-eclampsia 1. Anti-hypertensives o Given if BP reaches 150/100 mmHg o Urgently required at 160/110 mmHg Labetalol (beta-blocker)  Recommended for maintenance Nifedipine (CBB)  Oral  Used for initial control Oral nifedipine + IV labetalol  2nd line in severe HTN Treatment goal  BP about 140/90 mmHg  Anti-hypertensives do not change the course of the disease o Increase safety of mother o Reduce hospitalisation o May allow prolongation of pregnancy 2. Magnesium sulphate o Used both for treatment and in severe disease prevention of eclampsia o IV loading dose followed by IV infusion o NOT an anticonvulsant  but by  cerebral perfusion  probably treats the underlying pathology of eclampsia o REDUCE or STOP dose if renal impairment or anuria develops Pre-eclampsia Toxaemia (PET)  Respiratory depression + Hypotension  PRECEEDED by loss of patellar reflexes (test regularly) 3. Steroids o Promote foetal pulmonary maturity if gestation 36 weeks  prompt delivery o Conservative management before 36 o If foetal or maternal complications are likely to occur within 2 week of proteinuria onset Gestational Hypertension  Without foetal compromise  monitor for deterioration  Delivery by 40 weeks is usual Conduct of Delivery  Caesarean section o 34 weeks o Labour can be induced by prostaglandins 1. Epidural reduced BP 2. Foetus continually monitored by CTG 3. Monitor BP + fluid balance o Use antihypertensives 4. Avoid maternal pushing if BP >160/110 in the 2nd stage o This can raise intracranial pressure o Risk of cerebral haemorrhage 5. Oxytocin (Syntocinon) is used for the 3rd stage o Avoid ergometrine / ergot products   BP

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Pitfalls in Pre-eclampsia Management 1. HTN may be absent  beware f proteinuria 2. Epigastric pain is ominous 3. Liver function testing is mandatory 4. Must treat severe HTN 5. HTN treatment may disguise pre-eclampsia 6. Excessive fluid administration can cause pulmonary oedema 7. Complications commonly arise after delivery Post-natal Care  Often takes 24 hours for severe disease to improve after delivery Blood investigations

Fluid balance

Blood pressure

Long-term management

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 LFTS  Renal function  Platelets o Low platelet levels usually return to normal within a few days  Pulmonary oedema + respiratory failure can follow uncontrolled administration of IV fluids  Fluid restricted to  80 mL/h + losses  CVP will guide management if urine output is persistently low  Low CVP o Fluid but no albumin  High CVP o Suggesting overload o Furosemide  Normal CVP + oliguria o Renal failure likely o Rising potassium levels dictate need for dialysis  Maintained around 140/90 mmHg  Highest levels reached 4-5 days after birth  Post-natal Rx o Beta-blockers  2nd line Rx o Nifedipine (CCB) o ACE inhibitors  Rx may be needed for several weeks  GP / community midwife BP monitoring  6 weeks postpartum o If still HTN or proteinuria o Refer to renal / BP clinic

Mild Pre-eclampsia 1. 4 hourly BP o Include MAP o ([S+D]/3) + D 2. FHR 2x/day 3. 24-hour urine collection 4. TED stocking 5. Daily U/A 6. USS + UAD o Foetal growth / LV 7. If FGR  CTG 2x/day  Treat as potential emergency unless stable  If stable + mild = expectant management  Close monitoring as fulminant PET can occur Severe PET  BP  170/110 mmHg  on two occasions AND  Significant proteinuria  >0.5g/24h Clinical feature of severe PET 1. Severe headache 2. Visual disturbances 3. Epigastric pain / vomiting 4. 3 beat clonus 5. Papilloedema 6. Liver tenderness 7. Platelet count < 100x10^6 / L 8. ALT / AST >70 iu/L 9. Proteinuria 0.5g/24h 10. Creatine >120 mol/L 11. Pulmonary oedema 12. HELLP syndrome

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Treatment Hypertension

Pulmonary oedema / fluid overload Seizure

Respiratory depression

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Aim = 140-150 / 80-90 mmHg 1. Methyldopa (alpha-2 adrenergic agonist) 2. Nifedipine (CCB) 3. Labetalol (Beta-blocker) 4. Hydralazine (peripheral arterial vasodilator)  Strict balance  Monitor output  Magnesium sulphate (MgSO4)  58% reduction in developing seizures  Calcium gluconate  1g over 10 minutes...