Hypertensive Disorders of Pregnancy (HDP)

1. Hypertensive Disorders of Pregnancy (HDP) Maternal Newborn Orientation Learning Module Reproductive Care Program of Nova Scotia September, 2013

2. Objectives • To review classifications of HDP • To understand the maternal, fetal and neonatal implications • To highlight skilled nursing care of women with HDP • To review treatments and prevention of complications

3. Canadian Hypertension Education Program www.hypertension.ca/chep www.sogc.org

4. Hypertension in Pregnancy • Affects approximately 10% of all pregnancies • Is 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

5. Diagnosis of Hypertension* • dBP ≥ 90 mmHg • if dBP is < 90 mmHg but sBP is ≥ 140 mmHg, ‘close monitoring’ is advised Severe hypertension • sBP ≥ 160 mmHg and/or dBP ≥ 110 mmHg * Averaged over 2 measurements and (preferably) confirmed on 2 occasions; in 15 minutes if severe

6. Classification of HDP • Pre-existing hypertension – pre-pregnancy, or prior to 20 weeks gestation • Gestational hypertension – developing at or after 20 weeks gestation Two subgroups exist for both pre-existing and gestational hypertension: • with co-morbid conditions (e.g. diabetes, cardiovascular disease) • preeclampsia

7. Preeclampsia • More wide-ranging maternal and fetal implications than hypertension alone • Elevated BP (without preeclampsia) is of concern primarily as a potential cause of maternal morbidity • Described as a ‘potentially ominous disease peculiar to pregnancy’; a ‘pregnancy-specific syndrome of reduced organ perfusion (Gifford, et al, 2000)

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

9. Physiologic Changes During normal pregnancy: • Blood volume increases by 30% to 50% • Prostaglandin production is increased resulting in vasodilation and decreased vascular resistance • BP normally falls during the second trimester • Glomerular filtration rate increases by 50%; renal plasma flow increases by as much as 80% • BUN and serum creatinine decrease

10. Placental Physiology In 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

11. Pathophysiology of Preeclampsia • Placenta implantation is ineffective/incomplete • ‘Endothelial dysfunction’ associated with vascular reactivity and vasospasm • Blood flow is decreased • Placental perfusion may be significantly decreased • Maternal arteries become damaged, potentially leading to activation of coagulation cascade

12. ‘Progression’ of Preeclampsia • The condition begins at conception; the only ‘cure’ is delivery • Symptoms and adverse effects worsen as pregnancy advances

13. Severe Preeclampsia Criteria for classification of severe preeclampsia: • Onset <34 weeks gestation • One or more adverse conditions, and/or • Proteinuria 3 gm/d to 5 gm/d

14. Risk Factors for Preeclampsia • Ethnicity: Nordic, African Canadian, South Asian • Excessive weight gain • Family history • New partner • 1st pregnancy • Previous history • Age ≥ 40 • Obesity (BMI ≥ 35) • Pre-existing HTN • Multiple pregnancy • Inter-pregnancy interval < 2 years or ≥ 10 years

15. Maternal Complications • Eclampsia • Stroke • Pulmonary edema • Abruption • End organ dysfunction

16. Signs/Symptoms of End-Organ Dysfunction: • Headache • Visual disturbances • RUQ pain • Nausea/vomiting • Chest pain/dyspnea

17. Fetal Complications • Oligohydramnios • Intrauterine growth restriction (IUGR) • Absent or reversed end-diastolic flow in umbilical artery (Doppler) • Intrauterine fetal death (IUFD)

18. HELLP Syndrome • Commonly considered a variant of preeclampsia • Acronym for: • Hemolysis –  Hgb, LDH resulting from RBCs damaged by fibrin • Elevated Liver enzymes – AST, ALT from liver edema and damage from fibrin • Low Platelets – Thrombocytopenia < 150 x 109/L from  consumption of platelets due to damaged vascular endothelium

19. Caring for Women with HDP Antepartum fetal health surveillance • Encourage FM counting • Goal is 6 or more movements in 2 hours; at least daily and/or if  movement is perceived • If there are < 6 movements in 2 hours, ‘further assessments are advised’ (SOGC) • Ultrasound for fetal growth, AFV or BPP and/or umbilical artery Doppler

20. Caring for Women with HDP • No evidence to support introduction of a low salt diet; strict bed rest is not advised • Assess for signs and symptoms of complications or end-organ dysfunction associated with preeclampsia • Follow an appropriate and consistent procedure for assessing BP

21. Guidelines for Assessment of BP • Appropriate size cuff– 1 ½ times arm circumference • Standard (26-33 cm) • Large (33-41 cm) • Extra large (> 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

22. Steps for Taking an Accurate BP • A 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 minutes • A regularly calibrated aneroid device should be used; if used, an automated BP device should be validated for use with women with preeclampsia.

23. Taking an Accurate BP • Increase 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 beat • Note the first appearance of sound (phase I Korotkoff) – sBP and absence of sound (Phase V Korotkoff) – dBP

24. Taking an Accurate BP • Record the BP to the closest 2 mmHg on the manometer; record the woman’s pulse. • For the initial assessment, BP should be taken on both arms; the arm with the higher BP should be then used consistently.

25. Antihypertensive Therapy • Decisions about antihypertensive therapy are influenced by the presence of co-morbid conditions • Women without co-morbid conditions should have therapy to lower dBP to 80 to 105 mmHg • For 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

26. Non-Severe Hypertension • Labetolol • 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 pood (maximum 120 mg/d) • Methyldopa • 250 to 500 mg po bid to qid (maximum 2 g/day)

27. Therapy for Severe Hypertension • Labetolol • 20 mg IV; repeat 20 to 80 mg q 30 minutes, or 1 to 2 mg/min, to a maximum of 300 mg • Hydralazine • 5 mg IV; repeat 5 to 10 mg q 30 minutes, or 0.5 to 10 mg/hr, to a maximum of 20 mg • Nifedipine (oral) • 5 to 10 mg capsule (either bitten and swallowed or just swallowed), q 30 minutes, or • 10 mg PA tablet q 45 minutes, to a maximum of 80 mg/d

28. Points re Antihypertensives Note 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

29. Labour and Birth • Timing of birth depends on gestation, the presence and severity of complications and/or signs and symptoms of end-organ dysfunction • If gestation is < 34 weeks, administration of steroids will be considered • Induction (with cervical ripening, if necessary) is preferred unless there are other obstetrics indications for cesarean section

30. Other Considerations for Labour and Birth • Early anesthesia consultation is advised • Epidural/spinal anesthesia/analgesia is preferred, if indicated, provided platelets are >75 x 109/L • Platelets may be administered prior to vaginal or cesarean birth if < 20 to 50 x 109/L • RoutineIV bolus prior to administration of epidural medication or to improve abnormal EFM tracing is avoided • Antihypertensives are continued during labour

31. Magnesium Sulphate (MgSO4) • Given to prevent or treat eclampsia • IV loading dose (usually 4 gm), followed by 1 to 2 gm/hr • If a seizure occurs, another bolus will be given

32. Care of Women Receiving MgSO4 • Close assessment is indicated, including FHR • Avoid fluid overload; administer MgSO4 bolus in ≤ 100 ml of IV fluid • Calculate intake and output hourly; caution if urine output is low because the risk of magnesium toxicity increases • Assess for signs of magnesium toxicity: • weakness • hyporeflexia •  respiratory rate

33. Antidote • 10 ml of 10% solution of calcium gluconate given IV over 3 minutes • Stop MgSO4 infusion • Provide respiratory support

34. If a Seizure Occurs… • Call for help • Promote lateral position • Prepare MgSO4 bolus (and infusion if not already started) • Post seizure: • ensure adequacy of airway • check vital signs, O2 saturation, and FHR • assess for signs of abruption

35. Postpartum Care • Hypertension may worsen (or symptoms may first appear) following birth • BP peaks at day 3 to 6 • MgSO4 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

36. True/False Quiz • Stroke in pregnancy is unlikely unless sBP is >180 to 200 mmHg. T F • The BP goal for pregnant women with co-morbid conditions is 130 to 139/80 to 90 mmHg. T F • Pulmonary edema from fluid administration is a leading cause of death in women with preeclampsia. T F • MgSo4 is given to lower BP. T F

37. True/False Answers • Stroke in pregnancy is unlikely unless sBP is >180 to 200 mmHg. T F • The BP goal for pregnant women with co-morbid conditions is 130 to 139/80 to 90 mmHg. T F • Pulmonary edema from fluid administration is a leading cause of death in women with preeclampsia. T F • MgSo4 is given to lower BP. T F

38. Summary • Hypertensive 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.

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