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