Hypertension in Pregnancy

1. Hypertension in Pregnancy

2. Etiology & Definition • Complicates 10-20% of pregnancies • Elevation of BP ≥140 mmHg systolic and/or ≥90 mmHg diastolic, on two occasions at least 6 hours apart.

3. Categories • Chronic Hypertension • Gestational Hypertension • Preeclampsia • Preeclampsia superimposed on Chronic Hypertension

4. Chronic Hypertension • “Preexisting Hypertension” • Definition • Systolic pressure ≥ 140 mmHg, diastolic pressure ≥90 mmHg, or both. • Presents before 20th week of pregnancy or persists longer then 12 weeks postpartum. • Causes • Primary = “Essential Hypertension” • Secondary = Result of other medical condition (ie: renal disease)

5. Prenatal Care for Chronic Hypertensives • Electrocardiogram should be obtained in women with long-standing hypertension. • Baseline laboratory tests • Urinalysis, urine culture, and serum creatinine, glucose, and electrolytes • Tests will rule out renal disease, and identify comorbidities such as diabetes mellitus. • Women with proteinuria on a urine dipstick should have a quantitative test for urine protein.

6. Treatment for Chronic Hypertension Avoid treatment in women with uncomplicated mild essential HTN as blood pressure may decrease as pregnancy progresses. May taper or discontinue meds for women with blood pressures less than 120/80 in 1st trimester. Reinstitute or initiate therapy for persistent diastolic pressures >95 mmHg, systolic pressures >150 mmHg, or signs of hypertensive end-organ damage. Medication choices = Oral methyldopa and labetalol.

7. Preeclampsia • Definition = New onset of hypertension and proteinuria after 20 weeks gestation. • Systolic blood pressure ≥140 mmHg OR diastolic blood pressure ≥90 mmHg • Proteinuria of 0.3 g or greater in a 24-hour urine specimen • Preeclampsia before 20 weeks, think MOLAR PREGNANCY! • Categories • Mild Preeclampsia • Severe Preeclampsia • Eclampsia • Occurrence of generalized convulsion and/or coma in the setting of preeclampsia, with no other neurological condition.

8. Preeclampsia • Severe Preeclampsia must have one of the following: • Symptoms of central nervous system dysfunction = Blurred vision, scotomata, altered mental status, severe headache • Symptoms of liver capsule distention = Right upper quadrant or epigastric pain • Nausea, vomiting • Hepatocellular injury = Serum transaminase concentration at least twice normal • Systolic blood pressure ≥160 mm Hg or diastolic ≥110 mm Hg on two occasions at least six hours apart • Thrombocytopenia = <100,000 platelets per cubic milimeter • Proteinuria = 5 or more grams in 24 hours • Oliguria = <500 mL in 24 hours • Severe fetal growth restriction • Pulmonary edema or cyanosis • Cerebrovascular accident

9. Preeclampsia superimposed on Chronic Hypertension • Affects 10-25% of patients with chronic HTN • Preexisting Hypertension with the following additional signs/symptoms: • New onset proteinuria • Hypertension and proteinuria beginning prior to 20 weeks of gestation. • A sudden increase in blood pressure. • Thrombocytopenia. • Elevated aminotransferases.

10. Treatment of Preeclampsia • Definitive Treatment = Delivery • Major indication for antihypertensive therapy is prevention of stroke. • Diastolic pressure ≥105-110 mmHg or systolic pressure ≥160 mmHg • Choice of drug therapy: • Acute – IV labetalol, IV hydralazine, SR Nifedipine • Long-term – Oral methyldopa or labetalol

11. Gestational Hypertension • Mild hypertension without proteinuria or other signs of preeclampsia. • Develops in late pregnancy, after 20 weeks gestation. • Resolves by 12 weeks postpartum. • Can progress onto preeclampsia. • Often when hypertension develops <30 weeks gestation. • Indications for and choice of antihypertensive therapy are the same as for women with preeclampsia.

12. Risk Factors for Hypertension in Pregnancy • Nulliparity • Preeclampsia in a previous pregnancy • Age >40 years or <18 years • Family history of pregnancy-induced hypertension • Chronic hypertension • Chronic renal disease • Antiphospholipid antibody syndrome or inherited thrombophilia • Vascular or connective tissue disease • Diabetes mellitus (pregestational and gestational) • Multifetal gestation • High body mass index • Male partner whose previous partner had preeclampsia • Hydrops fetalis • Unexplained fetal growth restriction

13. Evaluation of Hypertension in Pregnancy • History • ID and Complaint • HPI (S/S of Preeclampsia) • Past Medical Hx, Past Family Hx • Past Obstetrical Hx, Past GyneHx • Social Hx • Medications, Allergies • Prenatal serology, blood work • Assess for Hypertension in Pregnancy risk factors • Physical • Vitals • HEENT = Vision • Cardiovascular • Respiratory • Abdominal = Epigastricpain, RUQ pain • Neuromuscular and Extremities = Reflex, Clonus, Edema • Fetus = Leopold’s, FM, NST

14. Evaluation of Hypertension in Pregnancy • Laboratory Tests • CBC (Hgb, Plts) • Renal Function (Cr, UA, Albumin) • Liver Function (AST, ALT, ALP, LD) • Coagulation (PT, PTT, INR, Fibrinogen) • Urine Protein (Dipstick, 24 hour)

15. Management of Hypertension in Pregnancy • Depends on severity of hypertension and gestational age!!!! • Observational Management • Restricted activity • Close Maternal and Fetal Monitoring • BP Monitoring • S/S of preeclampsia • Fetal growth and well being (NST, and U/S) • Routine weekly or biweekly blood work

16. Management of Hypertension in Pregnancy • Medical Management • Acute Therapy = IV Labetalol, IV Hydralazine, SR Nifedipine • Expectant Therapy = Oral Labetalol, Methyldopa, Nifedipine • Eclampsia prevention = MgSO4 • Contraindicated antihypertensive drugs • ACE inhibitors • Angiotensin receptor antagonists

17. Management of Hypertension in Pregnancy • Proceed with Delivery • Vaginal Delivery VS Cesarean Section • Depends on severity of hypertension! • May need to administer antenatal corticosteroids depending on gestation! • Only cure is DELIVERY!!!

18. Hypertension • Third leading cause of maternal mortality, after thromboembolism and non-obstetric injuries • Maternal DBP > 110 is associated with ↑ risk of placental abruption and fetal growth restriction • Superimposed preeclampsia cause most of the morbidity

19. Pregnancy Induced Hypertension • HTN • Usually mild and later in pregnancy • No renal or other systemic involvement • Resolves 12 wks postpartum • May become preeclampsia

20. Hypertension • Most common medical problem encountered during pregnancy • 8% of pregnancies • 4 categories: • Chronic Hypertension • Pregnancy Induced hypertension • Preeclampsia-eclampsia • Preeclampsia superimposed on chronic HTN *Hypertensive disorder in pregnancy may cause an increase in maternal and fetal morbidity and remains a leading source of maternal mortality*

21. Pregnancy Induced Hypertension • HTN • Usually mild and later in pregnancy • No renal or other systemic involvement • Resolves 12 wks postpartum • May become preeclampsia

22. Preeclampsia • New onset HTN • After 20 weeks of gestation, or • Early post-partum, previously normotensive • Resolves within 48 hrs postpartum • With the following (Renal or other systemic) • Proteinuria > 300 mg/24hr • Oliguria or Serum-plasma creatinine ratio > 0.09 mmol/L • Headaches with hyperreflexia, eclampsia, clonus or visual disturbances • ↑ LFTs, glutathione-S-Transferase alpha 1-1, alanine aminotransferase or right abdominal pain • Thrombocytopenia, ↑ LDH, hemolysis, DIC • 10% in primigravid • 20-25% with history of chronic HTN

23. Maternal Risk Factors • First pregnancy • Age younger than 18 or older than 35 • Prior h/o preeclampsia • Black race • Medical risk factors for preeclampsia - chronic HTN, renal disease, diabetes, anti-phospholipid syndrome • Twins • Family history

24. Mild vs. Severe Preeclampsia

25. Etiology Exact mechanism not known • Immunologic • Genetic • Placental ischemia • Endothelial cell dysfunction • Vasospasm • Hyper-responsive response to vasoactive hormones (e.g. angiotensin II & epinephrine)

26. Symptoms of preeclampsia • Visual disturbances • Headache • Epigastric pain • Rapidly increasing or nondependent edema - may be a signal of developing preeclampsia • Rapid weight gain - result of edema due to capillary leak as well as renal Na and fluid retention

27. Pathophysiology

28. Pathophysiology • Airway edema • Cardiac • Renal • Hepatic • Uterine

29. Upper airway edema • Upper airway edema • Laryngeal edema • Airway obstruction • Potential for airway compromise or difficulty in intubation

30. Cardiac/Pulmonary • Increased CO & SVR • CVP normal or slightly increased • Plasma volume reduced • Pulmonary edema • Decrease oncotic/collid pressure • Capillary/endothelial damage  leak • Vasoconstriction •  increase PWP and CVP • Occurs 3 % of preeclamptic patients

31. Hepatic • Usually mild • Severe PIH or preeclampsia complicated by HELLP  periportal hemorrhages ischemic lesion generalized swelling hepatic swelling  epigastric pain

32. Renal • Adversely affected  proteinuria • GFR and CrCl  decrease • BUN increase, may correlate w/ severity • RBF compromised • ARF w/ oliguria – PIH, esp. w/ abruption, DIC, HELLP *Oliguria + renal failure may occur in the absence of hypovolemia. Be careful w/ hydration  pulmonary edema*

33. Uterine • Activity increased • Hyperactive/hypersensitive to oxytocin • Preterm labor – frequent • Uterine/placental blood flow – decreased by 50-70% • Abruption – incidence increased

34. Morbidity / Mortality Maternal complications: • Leading cause of maternal death in PIH is intracranial hemorrhage • Seizures • Pulmonary edema • ARF • Proteinuria • Hepatic swelling with or without liver dysfunction • DIC (usually associated with placental abruption and is uncommon as a primary manifestation of preeclampsia)

35. Morbidity / Mortality Fetal complications: • Abruptio placentae • IUGR • Premature delivery • Intrauterine fetal death

36. HELLP Syndrome • Hemolysis • Elevated Liver enzymes • Low Platelets • < 36 wks • Malaise (90%), epigastric pain (90%), N/V (50%) • Self-limiting • Multi-system failure

37. HELLP Syndrome • Hemostasis is not problematic unless PLT < 40,000 • Rate of fall in PLT count is important • Regional anesthesia - contraindicated  fall is sudden • PLT count  normal within 72 hrs of delivery • Thrombocytopenia may persist for longer periods. • Definitive cure is delivery

38. Treatment • Management of maternal hemodynamics & prevention of eclampsia are key to a favorable outcome • MgSO4 - Rx of choice for preeclampsia. • Does not significantly reduce systemic BP at the serum concentration that are efficacious in treating preeclampsia • Goals • Control BP • Prevent seizures • Deliver the fetus

39. Controlling the HTN • Hydralazine • Labetalol • Nitroglycerin • Nifedipine • Esmolol • Na Nitroprusside – risk of cyanide toxicity in the fetus

40. Preventing Seizures • MgSO4 - Drug of choice. Narrow therapeutic index • Reduce > 50% w/o any serious maternal morbidity • 4g IV Bolus over 10 minutes, then infusion @ 1g/hr • Renal failure - rate of infusion  by serum Mg levels • Plasma Level should be between 4-6 mmol/L • Monitor clinical signs for toxicity • Toxic:10 ml of 10% Ca Gluconate IV slowly

41. MgSO4 Toxicity • 5-10 mEq/L – Prolonged PR, widened QRS • 11-14 mEq/L – Depressed tendon reflexes • 15-24 mEq/L – SA, AV node block, respiratory paralysis • >25 mEq/L - Cardiac arrest

42. Anesthetic Considerations • Detailed preanesthetic assessment • Focuses on airway, fluid status, and BP control • Lab: CBC, BUN/Cr, LFTs • Routine coagulation is NOT recommended unless there is clinical suspicion • PLT count - if neuraxial techniques are considered

43. Regional Anesthesia • Labor epidural - advantage of a gradual onset of sympathetic blockade  provides cardiovascular stability & avoids neonatal depression. • Epidurals may reduce vasospasm and HTN – may improve uteroplacental blood flow • Reduce risk of airway complications and avoid hemodynamic alterations associated with intubation

44. Regional (part 2) • Neuraxial anesthesia in preeclamptic pt - still controversial • Many studies  this is the best option • National High blood Pressure Education Program Working Group • “Neuraxial, epidural, spinal and combined spinal-epidural (CSE), techniques offer many advantages for labor analgesia and can be safely administered to the parturient with preeclampsia. Dilute epidural infusions of local anesthetic plus opioid produce adequate sensory block without motor block or clinically significant sympathectomy. “

45. Regional (part 3) • Possibility of extensive sympatholysis with profound hypotension •  decrease CO & uteroplacental perfusion • Single shot spinal technique  controversial • Recent analysis suggest that it can be used safety in pt with severe preeclampsia undergoing C-section. BP decline similar to epidural. Hypotension can be avoided by meticulous attention to anesthetic technique and careful volume expansion

46. General Anesthetic Techniques • Laryngeal response  blunted by pre-treatment with hydralazine, nitroglycerin or labetalol • Airway edema  increased risk of difficult airway situation • Neuraxial techniques  preferred method, contraindicated in the presence of coaguloapthy • In pt receiving MgSO4, SUX activity potentiated • Enhancedsensitivity to non-depolarizing muscle relaxants • MgSO4blunts response to vasconstrictors and inhibits catecholamine release after sympathetic stimulation

47. Thank You!