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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
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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