Hypertensive Disorders of Pregnancy (HDP)

Maternal Newborn Orientation Learning ModuleReproductive Care Program of Nova Scotia September, 2013

Hypertensive Disorders of Pregnancy (HDP)

.1ObjectivesTo review classifications of HDPTo understand the maternal, fetal and neonatal implicationsTo highlight skilled nursing care of women with HDPTo review treatments and prevention of complications

2www.sogc.org

Canadian HypertensionEducation Programwww.hypertension.ca/chep

3Hypertension in PregnancyAffects approximately 10% of all pregnanciesIs a leading cause of maternal and fetal/neonatal mortality and severe morbidity in Canada and the world. responsible for approximately 13% of maternal deaths in Canada

4Diagnosis of Hypertension*dBP 90 mmHgif dBP is < 90 mmHg but sBP is 140 mmHg, close monitoring is advisedSevere hypertension sBP 160 mmHg and/or dBP 110 mmHg

* Averaged over 2 measurements and (preferably) confirmed on 2 occasions; in 15 minutes if severe

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Classification of HDPPre-existing hypertension pre-pregnancy, or prior to 20 weeks gestationGestational hypertension developing at or after 20 weeks gestationTwo subgroups exist for both pre-existing and gestational hypertension: with co-morbid conditions (e.g. diabetes, cardiovascular disease)preeclampsia

6PreeclampsiaMore wide-ranging maternal and fetal implications than hypertension aloneElevated BP (without preeclampsia) is of concern primarily as a potential cause of maternal morbidityDescribed as a potentially ominous disease peculiar to pregnancy; a pregnancy-specific syndrome of reduced organ perfusion (Gifford, et al, 2000)

7Definition of Preeclampsia (SOGC)Hypertension (resistant, if pre-existing)Proteinuria dipstick result of +2 or 24-hour collection of 0.3 to 0.5g/dAdverse conditions resulting from end-organ dysfunction including:complications such as oligohydramnios symptoms of headache, visual disturbances or RUQ painabnormal lab tests - decreased platelet count or elevated liver enzymes (*results in pregnancy may differ from standard values)

8Physiologic ChangesDuring normal pregnancy:Blood volume increases by 30% to 50%Prostaglandin production is increased resulting in vasodilation and decreased vascular resistanceBP normally falls during the second trimesterGlomerular filtration rate increases by 50%; renal plasma flow increases by as much as 80% BUN and serum creatinine decrease

9Placental PhysiologyIn normal pregnancies:Placental implantation results in remodeling of the uterine spiral arteries.The result is large capacity vessels with low resistance, allowing increased placental blood flow and oxygenation

Spiral artereries

. 10Pathophysiology of PreeclampsiaPlacenta implantation is ineffective/incompleteEndothelial dysfunction associated with vascular reactivity and vasospasmBlood flow is decreasedPlacental perfusion may be significantly decreasedMaternal arteries become damaged, potentially leading to activation of coagulation cascade

11Progression of PreeclampsiaThe condition begins at conception; the only cure is deliverySymptoms and adverse effects worsen as pregnancy advances

12Severe PreeclampsiaCriteria for classification of severe preeclampsia:Onset 41 cm)Woman should be sitting with the cuff positioned at the level of the heart

Reprinted with permission of the Canadian Hypertension Education Program

21Steps for Taking an Accurate BPA woman should rest comfortably for 5 minutes prior to taking BP; she should be seated with her feet resting on floor (or other), legs uncrossed with her arm well supported; she should not be talking during the assessment. No caffeine or nicotine within 30 minutesA regularly calibrated aneroid device should be used; if used, an automated BP device should be validated for use with women with preeclampsia.

22Taking an Accurate BPIncrease cuff pressure rapidly to approximately 30 mmHg above the disappearance of the radial pulse.Open the control valve so that the rate of deflation of the cuff is approximately 2 mmHg per heart beatNote the first appearance of sound (phase I Korotkoff) sBP and absence of sound (Phase V Korotkoff) dBP

Taking an Accurate BPRecord the BP to the closest 2 mmHg on the manometer; record the womans pulse.For the initial assessment, BP should be taken on both arms; the arm with the higher BP should be then used consistently.

Antihypertensive TherapyDecisions about antihypertensive therapy are influenced by the presence of co-morbid conditionsWomen without co-morbid conditions should have therapy to lower dBP to 80 to 105 mmHgFor women with co-morbid conditions, the goal is for sBP to be 130 to 139 mmHg, and the dBP to be 80 to 90 mmHg

25Non-Severe HypertensionLabetolol 100 to 400 mg bid to tid (maximum 2g/day)Nifedipine PA tablets (intermediate release) 10 to 20 mg po bid to tid (maximum 1200 mg/day)XL tablets (slow-release) 20 to 60 mg po od (maximum 120 mg/d)Methyldopa 250 to 500 mg po bid to qid (maximum 2 g/day)

26Therapy for Severe HypertensionLabetolol20 mg IV; repeat 20 to 80 mg q 30 minutes, or 1 to 2 mg/min, to a maximum of 300 mgHydralazine5 mg IV; repeat 5 to 10 mg q 30 minutes, or 0.5 to 10 mg/hr, to a maximum of 20 mgNifedipine (oral)5 to 10 mg capsule (either bitten and swallowed or just swallowed), q 30 minutes, or10 mg PA tablet q 45 minutes, to a maximum of 80 mg/d

27Points re AntihypertensivesNote that there are 3 preparations of Nifedipine - capsules, intermediate-release tablets (PA), and slow-release tablets (SL)Care must be taken to avoid a drop in dBP to < 80 mmHg as uteroplacental perfusion may be adversely affected. Women with preeclampsia are more likely to experience hypotension with antihypertensive treatment.Atenolol is not advised because of negative effects on fetal growth; ACE inhibitors and ARBs are fetotoxic, especially to the fetal kidneys

28Labour and BirthTiming of birth depends on gestation, the presence and severity of complications and/or signs and symptoms of end-organ dysfunctionIf gestation is < 34 weeks, administration of steroids will be consideredInduction (with cervical ripening, if necessary) is preferred unless there are other obstetrics indications for cesarean section

29Other Considerations for Labour and BirthEarly anesthesia consultation is advisedEpidural/spinal anesthesia/analgesia is preferred, if indicated, provided platelets are >75 x 109/LPlatelets may be administered prior to vaginal or cesarean birth if < 20 to 50 x 109/LRoutine IV bolus prior to administration of epidural medication or to improve abnormal EFM tracing is avoidedAntihypertensives are continued during labour

30Magnesium Sulphate (MgSO4)Given to prevent or treat eclampsiaIV loading dose (usually 4 gm), followed by 1 to 2 gm/hrIf a seizure occurs, another bolus will be given

31Care of Women Receiving MgSO4Close assessment is indicated, including FHRAvoid fluid overload; administer MgSO4 bolus in 100 ml of IV fluidCalculate intake and output hourly; caution if urine output is low because the risk of magnesium toxicity increasesAssess for signs of magnesium toxicity:weaknesshyporeflexia respiratory rate

32Antidote10 ml of 10% solution of calcium gluconate given IV over 3 minutes Stop MgSO4 infusionProvide respiratory support

If a Seizure OccursCall for helpPromote lateral positionPrepare MgSO4 bolus (and infusion if not already started)Post seizure:ensure adequacy of airwaycheck vital signs, O2 saturation, and FHRassess for signs of abruption

Postpartum CareHypertension may worsen (or symptoms may first appear) following birth BP peaks at day 3 to 6MgSO4 will be continued usually 24 hours (duration varies)NSAIDs should not be used if BP is difficult to control, platelets are < 50 x 109/L, there is oliguria, or elevated creatinine

True/False QuizStroke in pregnancy is unlikely unless sBP is >180 to 200 mmHg. TFThe BP goal for pregnant women with co-morbid conditions is 130 to 139/80 to 90 mmHg.TFPulmonary edema from fluid administration is a leading cause of death in women with preeclampsia. TFMgSo4 is given to lower BP.TF

36True/False AnswersStroke in pregnancy is unlikely unless sBP is >180 to 200 mmHg. TFThe BP goal for pregnant women with co-morbid conditions is 130 to 139/80 to 90 mmHg.TFPulmonary edema from fluid administration is a leading cause of death in women with preeclampsia. TFMgSo4 is given to lower BP.TF

37SummaryHypertensive Disorders of Pregnancy are associated with a number of potentially serious maternal, fetal and pregnancy complications.Careful assessment for development of a HDP is essential throughout pregnancy, during labour and in the postpartum period.

38Thank you!

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