Gestational Hypertension

Gestational HypertensionInternational

Gestational Hypertension

Gestational HypertensionInternational

Objectives• Definitions• Diagnosis• Management

- Fetal / Maternal assessment- Anti-Hypertensive therapy- Anti-Seizure therapy- Transport

Gestational HypertensionInternational

Definitions• Preexisting hypertension• Gestational hypertension

- without proteinuria - with proteinuria - with proteinuria and adverse conditions

• Preexisting hypertension with superimposed gestational hypertension with proteinuria

• Unclassifiable antenatally

Gestational HypertensionInternational

Definitions• Hypertension

- absolute value of 140/90 mmHg incremental rise of 30/15 mmHg diastolic BP of ³ 90 mmHg

• sitting position with arm at heart level• appropriate size cuff• accurate mercury sphygmomanometer• Korotkoff sounds I and IV recorded• confirm BP in 4 hours unless very high

Gestational HypertensionInternational

Definitions• Proteinuria

- urine protein 2+ on dipstick- urine protein 300 mg/d on 24 hour collection

• proteinuria indicates glomerular dysfunction• 24 hour urine should be considered if urine protein

1+ on dipstick• edema may result from vasospasm and decreased

oncotic pressure but this is not part of the definition

Gestational HypertensionInternational

Manifestations of SeverityGestational hypertension with adverse conditions

• diastolic BP > 110 mmHg• laboratory evidence - platelets, LFT's, uric acid• renal effects - proteinuria > 3 g/d, oliguria• CNS effects - seizure, headache, visual disturbances• other organ involvement - lung, liver, hematologic• fetal compromise

- previously known as severe preeclampsia

Gestational HypertensionInternational

Incidence• 10% of all pregnancies complicated by hypertension

- one third of these will have proteinuria• majority of preeclampsia in nulliparous patients

- increased mortality risk in older gravidas- increased risk in first pregnancy with new partner- increased risk with preexisting hypertension, renal

disease, diabetes mellitus• preeclampsia is a leading cause of direct maternal

mortality

Gestational HypertensionInternational

Management• Stress reduction first• Assessment of mother and fetus• Treat blood pressure if dBP > 110 mmHg• Treat nausea and vomiting• Treat epigastric pain• Consider seizure prophylaxis• Consider timing/mode of delivery

Gestational HypertensionInternational

Stress Reduction• component of maternal BP is adrenergic• maternal discomfort must be minimized• several components

- quiet, dimly lit, isolated room - well planned management protocol- clear explanation of plan to patient/family- minimization of negative stimuli- consistent, confident team approach

nursing, obstetrics, anaesthesia, hematology, pediatrics

Gestational HypertensionInternational

Assessment of Mother - Clinical• Blood Pressure

- assess severity- consistency in measuring- relationship of high BP to CVA not seizure

• Central Nervous System- presence and severity of headache- vision disturbances - blurring, scotomata- tremulousness, irritability, hyperreflexia, somnolence- nausea and vomiting

Gestational HypertensionInternational

Assessment of Mother - Clinical• Hematologic

- edema- bleeding, petechiae

• Hepatic- RUQ and epigastric pain- nausea and vomiting

• Renal- urine output and colour

Gestational HypertensionInternational

Assessment of Mother - Laboratory• Hematologic

- hemoglobin, platelets, blood film- PTT, INR, fibrinogen, FDP- LDH, uric acid, bilirubin

• Hepatic- ALT, AST- (glucose, ammonia to R/O AFLP)

• Renal- proteinuria- creatinine, urea, uric acid

Gestational HypertensionInternational

Assessment of Fetus• Fetal movement• Fetal heart rate assessment• Ultrasound for growth• Biophysical profile• Amniotic fluid volume• Doppler flow studies

Gestational HypertensionInternational

Treatment• Nausea and Vomiting

- antiemetic of choice

• RUQ / Epigastric Pain- morphine 2 - 4 mg IV- antacid- minimize palpation

Gestational HypertensionInternational

Anti-hypertensive Therapy - Goals• minimize risk of maternal CVA• maximize maternal condition for safe delivery• gain time for further assessment

- facilitate vaginal delivery if possible- prolong gestation where appropriate/feasible

Gestational HypertensionInternational

Anti-hypertensive Agents - Acute Therapy• Arteriolar Dilators

- hydralazine

• ß-Blockers- labetalol

• Calcium Channel Blockers- nifedipine

Gestational HypertensionInternational

Anti-hypertensive Agents - Maintenance Therapy

• Centrally Acting Sympatholytic Agents- methyl-dopa

• ß-Blockers- atenolol- labetalol

• Calcium Channel Blockers- nifedipine

ACE inhibitors are contraindicated in pregnancy

Gestational HypertensionInternational

Hydralazine• direct vasodilator, first line agent in acute settings• intravenous rapid onset useful for hypertensive crisis• can be used orally• Dosage - 5 mg IV test dose 5-10 mg q 20-40 minutes• Cautions - hypotension with fetal compromise may occur

in slow acetylators and hypovolemic patients • Side Effects - may cause flushing, headache, tachycardia

Gestational HypertensionInternational

Methyldopa• centrally acting a2-receptor agonist, oral agent• long history of safe use in pregnancy, well tolerated• some concern regarding ability to control BP• not for use in acute settings• Dosage - 500 - 3000 mg po in 2 - 4 divided doses• Cautions - drug of choice in essential hypertension• Benefits - minimal side-effects and safe

Gestational HypertensionInternational

Atenolol• ß1-receptor antagonist, oral agent cardiac output, renin release, vasomotor inhibitor• onset of action in 1 hour peak levels in 2-4 hours• long half life once a day dosing• Dosage - 50 -100 mg po OD• Cautions - DM, asthma, baseline FH, variability present

- risk of IUGR with chronic use• Benefits - often only agent needed

Gestational HypertensionInternational

Labetalol• combined 1 and ß-blocker with ISA• intravenous rapid onset useful for hypertensive crisis• can be used orally• Dosage - maximum 300 mg IV dose

- 20 mg IV followed by 20-80 mg IV titrated to BP• Cautions - concern re: fetal responses to hypoxia• Benefits - dependable, titratable, familiar

Gestational HypertensionInternational

Nifedipine• calcium channel blocker, oral agent• direct relaxation of vascular smooth muscle• rapid onset of action if regular capsule used• Dosage - Adalat-PA 10 mg bid 40 mg bid• Side Effects - magnesium toxicity, edema, flushing,

headache, palpitations, tocolytic

use of short acting form discouraged

Gestational HypertensionInternational

Hypertensive Crisis• Stabilize severe hypertension

- use hydralazine, ß-blocker, and/or Adalat-PA- goal maintain diastolic BP at 90 - 100 mmHg- monitor fetal status while treating BP

• Seizure prophylaxis• Intravascular volume status

- Foley catheter seldom experience ARF- do not fluid overload seldom require CVP line

• Deliver

Gestational HypertensionInternational

Seizure Prophylaxis • difficult to predict who will seize

- not directly related to degree of hypertension or level of proteinuria

• high 'number needed to treat' to prevent seizure

• agents not innocuous nor completely effective

• MgSO4 is agent of choice when seizure prophylaxis is felt to be indicated

Gestational HypertensionInternational

Magnesium Sulfate• obstetrical standard but not used in other settings• superior to phenytoin for prophylaxis• superior to phenytoin or diazepam in preventing recurrence

• Dosage - 4 g IV followed by 1 - 4 g / hour IV or 4 g IM q4h• Side Effects - weakness, paralysis, cardiac toxicity• Monitor - reflexes, respiration, level of consciousness

Gestational HypertensionInternational

Magnesium Sulfate - Overdose• close observation for side effects

- weakness, respiratory paralysis, somnolence• especially high risk in those with oliguria or

receiving Ca2+ channel blockers

ANTIDOTE• stop magnesium infusion • 10% Calcium gluconate 10 mL IV over 3 minutes

Gestational HypertensionInternational

Transport• consider transport only if resources limited and

maternal/fetal condition permits • maternal BP and symptoms stable• fetal status reassuring• appropriate anti-hypertensive agents started• MgSO4 started if appropriate • discuss with accepting centre and patient/family• MgSO4 and anti-hypertensives potentially fatal in overdose

Gestational HypertensionInternational

When to Deliver 37 weeks with gestational hypertension 34 weeks with severe gestational hypertension• < 34 weeks with any of:

- poorly controlled dBP- lab evidence of worsening end-organ involvement- suspected fetal compromise- uncontrolled seizures- symptoms unresponsive to appropriate therapy

Gestational HypertensionInternational

Delivery - The Cure• timely delivery minimizes maternal and neonatal

morbidity and mortality • optimize maternal status before interventions to deliver• delay delivery to gain fetal maturity and to allow transfer

only when maternal and fetal condition allow it

• gestational hypertension is a progressive disease, expectant management is potentially harmful in presence of severe disease or suspected fetal compromise

Gestational HypertensionInternational

Peri- and Postpartum Management• do not drop BP too low risking fetal compromise• do not fluid overload• epidural analgesia is favoured in the absence of

low platelets or coagulopathy • multi-specialty approach• patient must be monitored post-partum