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Hypertension

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. Introduction.

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Hypertension

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  1. 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

  2. Introduction • Most common medical complication of pregnancy • 6 to 8 % of gestations in the US. • In 2000, the National High Blood Pressure Education Program Working Group on High Blood Pressure in Pregnancy defined four categories of hypertension in pregnancy: • Chronic hypertension • Gestational hypertension • Preeclampsia • Preeclampsia superimposed on chronic hypertension

  3. Chronic Hypertension Defined • BP measurement of 140/90 mm Hg or more on two occasions • Before 20 weeks of gestation OR Persisting beyond 12 weeks postpartum

  4. Chronic Hypertension • Treatment of mild to moderate chronic hypertension neither benefits the fetus nor prevents preeclampsia. • Excessively lowering blood pressure may result in decreased placental perfusion and adverse perinatal outcomes. • When BP is 150 to 180/100 to 110 mm Hg, pharmacologic treatment is needed to prevent maternal end-organ damage.

  5. Treatment of Chronic Hypertension • Methyldopa , labetalol, and nifedipine most common oral agents. • AVOID: ACEI and ARBs, atenolol, thiazide diuretics • Women in active labor with uncontrolled severe chronic hypertension require treatment with intravenous labetalol or hydralazine.

  6. Gestational Hypertension • Formerly called PIH (Pregnancy Induced HTN) • HTN without proteinuria occurring after 20 weeks gestation and returning to normal within 12 weeks after delivery. • 50% of women diagnosed with gestational hypertension between 24 and 35 weeks develop preeclampsia.

  7. Older Criteria for Gestational HTN • 30/15 increase in BP over baseline levels • No longer appropriate • 73% of patients will exceed 30 mm systolic and 57% will exceed 20 mm diastolic

  8. Preeclampsia • New onset hypertension with proteinuria after 20 weeks gestation. • Resolves by 6 weeks postpartum. • Characterized as mild or severe based on the degree of hypertension and proteinuria, and the presence of symptoms resulting from involvement of the kidneys, brain, liver, and cardiovascular system

  9. 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

  10. Diagnostic Criteria for Preeclampsia • SBP of 140 mm Hg or more or a DBP of 90 mm Hg or more on two occasions at least six hours apart after 20 weeks of gestation AND • Proteinuria – 300 mg in a 24-hour urine specimen or 1+ or greater on urine dipstick testing of two random urine samples collected at least four hours apart. • A random urine protein/creatinine ratio < 0.21 indicates that significant proteinuria is unlikely with a NPV of 83%. • Generalized edema (affecting the face and hands) is often present in patients with preeclampsia but is not a diagnostic criterion.

  11. Mild vs. Severe Preeclampsia

  12. HELLP Syndrome • Is a variant of severe preeclampsia • Occurs in up to 20% of pregnancies complicated by severe preeclampsia. • Variable clinical presentation; 12 to 18% are normotensive and 13% do not have proteinuria. • At diagnosis, 30% of women are postpartum, 18% are term, and 52% are preterm.

  13. HELLP Syndrome • Common presenting complaints are RUQ or epigastric pain, N/V, malaise or nonspecific symptoms suggesting an acute viral syndrome. • Any patient with these symptoms or signs of preeclampsia should be evaluated with CBC, platelet count, and liver enzymes. • When platelet count < 50,000/mm3 or active bleeding occurs, coagulation studies needed to R/O DIC.

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

  15. 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

  16. Prevention of Preeclampsia • Routine supplementation with calcium, magnesium, omega-3 fatty acids, or antioxidant vitamins is ineffective. • Calcium reduces the risk of developing preeclampsia in high-risk women and those with low dietary calcium intake. • Low-dose aspirin (75 to 81 mg per day) is effective for women at increased risk of preeclampsia, NNT = 69 ; NNT = 227 to prevent one fetal death. • Low-dose aspirin is effective for women at highest risk from previous severe preeclampsia, diabetes, chronic hypertension, or renal or autoimmune disease, NNT = 18.

  17. Multiorgan Effects of Preeclamsia • Cardiovascular – HTN, increased cardiac output, increased systemic vascular resistance, hypovolemia • Neurological – Seizures-eclampsia, headache, cerebral edema, hyperreflexia • Pulmonary – Capillary leak, reduced colloid osmotic pressure, pulmonary edema

  18. Multiorgan Effects cont…. • Hematologic – Volume contraction, elevated hematocrit, low platelets, anemia due to hemolysis • Renal – Decreased GFR, increased BUN/creatinine, proteinuria, oliguria, ATN • Fetal – Increased perinatal morbidity, placental abruption, fetal growth restriction, oligohydramnios, fetal distress • Uterine - Activity increased, Hyperactive/hypersensitive to oxytocin, Preterm labor – frequent, Uterine/placental blood flow – decreased by 50-70%, Abruption – incidence increased

  19. Management of Preeclampsia • The ultimate cure is DELIVERY. • Assess gestational age • Assess cervix • Fetal well-being • Laboratory assessment • Rule out severe disease

  20. Gestational HTN at Term • Delivery is always a reasonable option if term • If cervix is unfavorable and maternal disease is mild, expectant management with close observation is possible

  21. Mild Gestational HTN Not at Term • Rule out severe disease • Conservative management • Serial labs • Twice weekly visits • Antenatal fetal surveillance • Outpatient versus inpatient

  22. Indications for Delivery in Preeclampsia • Fetal indications • Severe intrauterine growth restriction • Nonreassuring fetal surveillance • Oligohydramnios

  23. Indications for Delivery in Preeclampsia • Maternal indications • Gestational age of 38 weeks or greater • Platelet count below 100,000 • Progressive deterioration of hepatic or renal function • Suspected placental abruption • Persistent severe headache or visual changes • Persistent severe epigastric pain, nausea, or vomiting • Eclampsia

  24. Criteria for Treatment • Diastolic BP > 105-110 • Systolic BP > 200 • Avoid rapid reduction in BP • Do not attempt to normalize BP • Goal is DBP < 105 not < 90 • May precipitate fetal distress

  25. Hypertensive Emergencies • Fetal monitoring • IV access • IV hydration to maintain urine output > 30 mL per hour, limit to 100 mL per hour. • The reason to treat is maternal, not fetal • May require ICU

  26. Characteristics of Severe HTN • Crises are associated with hypovolemia • Clinical assessment of hydration is inaccurate • Unprotected vascular beds are at risk, ie., uterine

  27. Key Steps Using Vasodilators • 250-500 cc of fluid, IV • Avoid multiple doses in rapid succession • Allow time for drug to work • Maintain LLD position • Avoid over treatment

  28. Acute Medical Therapy • Hydralazine • Labetalol • Nifedipine • Nitroprusside • Clonidine

  29. Hydralazine • Dose: 5-10 mg every 20 minutes • Onset: 10-20 minutes • Duration: 3-8 hours • Side effects: headache, flushing, tachycardia, lupus like symptoms • Mechanism: peripheral vasodilator

  30. Labetalol • Dose: 20 mg, then 40, then 80 every 20 minutes, for a total of 220mg • Onset: 1-2 minutes • Duration: 6-16 hours • Side effects: hypotension • Mechanism: Alpha and Beta blockade

  31. Nifedipine • Dose: 10 mg po, not sublingual • Onset: 5-10 minutes • Duration: 4-8 hours • Side effects: chest pain, headache, tachycardia • Mechanism: CA channel blockade

  32. Clonidine • Dose: 1 mg po • Onset: 10-20 minutes • Duration: 4-6 hours • Side effects: unpredictable, avoid rapid withdrawal • Mechanism: Alpha agonist, works centrally

  33. Nitroprusside • Dose: 0.2 – 0.8 mg/min IV • Onset: 1-2 minutes • Duration: 3-5 minutes • Side effects: cyanide accumulation, hypotension • Mechanism: direct vasodilator

  34. Seizure Prophylaxis • Magnesium sulfate • Loading dose of 4 to 6 g diluted in 100 mL of normal saline, given IV over 15 to 20 minutes, followed by a continuous infusion of 1-2 g per hour • Monitor urine output, RR and DTR’s • With renal dysfunction, may require a lower dose

  35. Magnesium Sulfate • Is NOT a hypotensive agent • Works as a centrally acting anticonvulsant • Also blocks neuromuscular conduction • Serum levels: 4-7 mg/dL • Additional benefit of reducing the incidence of placental abruption

  36. Toxicity • Respiratory rate < 12 • DTR’s not detectable • Altered sensorium • Urine output < 25-30 cc/hour • Antidote: 10 ml of 10% solution of calcium gluconate 1 g IV over 2 minutes.

  37. Eclampsia • New onset of seizures in a woman with pre-eclampsia. • Preceded by increasingly severe preeclampsia, or it may appear unexpectedly in a patient with minimally elevated blood pressure and no proteinuria. • Blood pressure is only mildly elevated in 30-60% of women who develop eclampsia. • Occurs: Antepartum - 53%, intrapartum - 19%, or postpartum - 28%

  38. Treatment of Eclampsia • Protecting the patient and her airway • Place patient on left side and suction to minimize the risk of aspiration • Give oxygen • Avoid insertion of airways and padded tongue blades • IV access • Mag Sulfate 4-6 g IV bolus, if not effective, give another 2 g

  39. Alternate Anticonvulsants • Diazepam 5-10 mg IV • Sodium Amytal 100 mg IV • Pentobarbital 125 mg IV • Dilantin 500-1000 mg IV infusion

  40. After the Seizure • Assess maternal labs • Fetal well-being • Effect delivery • Transport when indicated • No need for immediate cesarean delivery

  41. Other Complications • Pulmonary edema • Oliguria • Persistent hypertension • DIC

  42. Pulmonary Edema • Fluid overload • Reduced colloid osmotic pressure • Occurs more commonly following delivery as colloid oncotic pressure drops further and fluid is mobilized

  43. Treatment of Pulmonary Edema • Avoid over-hydration • Restrict fluids • Lasix 10-20 mg IV • Usually no need for albumin or Hetastarch (Hespan)

  44. Oliguria • 25-30 cc per hour is acceptable • If less, small fluid boluses of 250-500 cc as needed • Lasix is not necessary • Postpartum diuresis is common • Persistent oliguria almost never requires a PA cath

  45. Persistent Hypertension • BP may remain elevated for several days • Diastolic BP less than 100 do not require treatment • By definition, preeclampsia resolves by 6 weeks

  46. Disseminated Intravascular Coagulopathy • Rarely occurs without abruption • Low platelets is not DIC • Requires replacement blood products and delivery

  47. Anesthesia Issues • Continuous lumbar epidural is preferred if platelets normal • Need adequate pre-hydration of 1000 cc • Level should always be advanced slowly to avoid low BP • Avoid spinal with severe disease

  48. SORT: KEY RECOMMENDATIONS FOR PRACTICE • In women without end-organ damage, chronic hypertension in pregnancy does not require treatment unless the patient's blood pressure is persistently greater than 150 to 180/100 to 110 mm Hg. – C • Calcium supplementation decreases the incidence of hypertension and preeclampsia, respectively, among all women (NNT = 11 and NNT = 20), women at high risk of hypertensive disorders (NNT = 2 and NNT = 6), and women with low calcium intake (NNT = 6 and NNT = 13). – A

  49. Low-dose aspirin (75 to 81 mg daily) has small to moderate benefits for the prevention of preeclampsia (NNT = 72), preterm delivery (NNT = 74), and fetal death (NNT = 243). The benefit of aspirin is greatest (NNT = 19) for prevention of preeclampsia in women at highest risk (previous severe preeclampsia, diabetes, chronic hypertension, renal disease, or autoimmune disease). – B • For women with mild preeclampsia, delivery is generally not indicated until 37 to 38 weeks of gestation and should occur by 40 weeks. – C

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