gestational hypertension. objectives definitions diagnosis management -fetal / maternal assessment...

Gestational HypertensionInternational

Gestational Hypertension


Objectives

• Definitions• Diagnosis• Management

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


Definitions• Preexisting hypertension

• Gestational hypertension- without proteinuria - with proteinuria - with proteinuria and adverse conditions

• Preexisting hypertension with superimposed gestational hypertension with proteinuria

• Unclassifiable antenatally


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


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


Manifestations of Severity

Gestational 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


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


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


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


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


Assessment of Mother - Clinical

• Hematologic- edema- bleeding, petechiae

• Hepatic- RUQ and epigastric pain- nausea and vomiting

• Renal- urine output and colour


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


Assessment of Fetus

• Fetal movement

• Fetal heart rate assessment

• Ultrasound for growth

• Biophysical profile

• Amniotic fluid volume

• Doppler flow studies


Treatment

• Nausea and Vomiting- antiemetic of choice

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


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


Anti-hypertensive Agents - Acute Therapy

• Arteriolar Dilators- hydralazine

• ß-Blockers- labetalol

• Calcium Channel Blockers- nifedipine


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


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


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


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


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


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


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


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


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


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


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


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


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


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

gestational hypertension. objectives definitions diagnosis management -fetal / maternal assessment...

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