Hypertensive Disorders of Pregnancy

Post a comment   Post Comment on Twitter


     1  Hypertensive Disorders of Pregnancy Michael Moxley, MD
     2  Learning Objectives Define chronic hypertension of pregnancy Define preeclampsia and eclampsia Discuss the etiologies of and risk factors for hypertensive disorders of pregnancy Review the clinical management of hypertensive disorders of pregnancy
     3  Definitions
     4  Chronic hypertension in pregnancy Mild – SBP>=140mmHg, DBP>=90mmHg Severe – SBP>=180, DBP>=110 Using antihypertensives before pregnancy Onset before 20 weeks EGA Persistence beyond postpartum period (12 weeks)
     5  Preeclampsia A clinical diagnosis defined by a classic triad: Hypertension (BP = 140/90) Proteinuria (1+ dipstick or 300 mg/24 hr) [Edema (especially non-dependent)] No longer considered a required component Mild preeclampsia meets the above criteria
     6  Severe Preeclampsia Any one of the following: Blood pressure sustained above 160/110 Proteinuria >2+ dipstick or > 5 gm/24 hr Headache/visual disturbances Epigastric pain Oliguria (< 500 mL/24 hours) HELLP syndrome Fetal growth restriction
     7  Eclampsia Seizure activity unrelated to other central nervous system disorders (epilepsy, meningitis, mass lesion, intracranial hemorrhage), with or without resultant coma Associated with ~50,000 maternal deaths (10% of total) worldwide each year
     8  Incidence 12 – 22% pregnancies – affected by hypertensive diseases during pregnancy 5% - chronic hypertension in pregnancy. 5-8% - preeclampsia, 10% of whom develop eclampsia Hypertensive diseases - responsible for 17.6% of maternal deaths in the US. In 2003, there were 495 pregnancy-associated deaths, 68 (14%) due to hypertension.
     9  Maternal Death Definitions Pregnancy-associated death – death during pregnancy or within 1 year of end of pregnancy, regardless of cause Pregnancy-related death – death in this time period, related to pregnancy itself or a health condition worsened by pregnancy Not-pregnancy-related death – death in this time period due to incidental or accidental causes, i.e. unrelated to pregnancy
     10  Maternal Death Definitions Pregnancy-related death sub-classification Direct maternal death - maternal death resulting directly from obstetric causes Indirect maternal death - maternal death resulting from a medical illness that predated or developed during the pregnancy
     11  Risk Factors Nulliparity Previous pregnancy with preeclampsia Family history of preeclampsia Chronic hypertension (30%) Diabetes mellitus (30-50%) Shorter duration of sexual cohabitation with father of pregnancy (primipaternity)
     12  Risk Factors Renal disease (30-50%) Connective tissue diseases Multiple gestation Hydatidiform mole Certain fetal anomalies (e.g. sacrococcygeal teratoma, triploidy) Age > 35 African-American race
     13  Pathophysiology Incompletely understood Thought to stem from inadequate invasion of trophoblast into the myometrium This lack of invasion allows the myometrial portion of the spiral arterioles to maintain their muscular walls, preventing development of the normal low-resistance uteroplacental circulation.
     14  Pathophysiology Increased vascular reactivity Increased platelet activation Altered prostanoid balance favoring production of TXA2 and PGF2 (vasoconstrictors, platelet aggregators) over PGI2 and PGE (vasodilators, platelet dis-aggregators).
     15  Pathophysiologic manifestations Alterations are seen in nearly every system: Hematologic Thrombocytopenia, hemolysis, increased platelet activation Cardiovascular Vasospasm, hemoconcentration Renal Proteinuria, oliguria, ATN, acute renal failure
     16  Pathophysiologic manifestations Hepatic Elevated transaminases, hyperbilirubinemia, hepatic hemorrhage Neurologic Headache, scotomata, blurred vision, hyperreflexia, temporary blindness, seizures
     17  Pathophysiologic manifestations Fetoplacental IUGR, oligohydramnios, abruption, impaired gas exchange, nonreassuring fetal status
     18  HELLP Syndrome Occurs in up to 20% of women with severe preeclampsia, more commonly in white women and multigravid women H-Hemolysis EL-Elevated liver function tests AST> 72 IU; LDH > 600 IU LP-Low platelets
     19  Chronic Hypertension - Evaluation Specialized testing, ideally prior to pregnancy (ECHO, ECG, ophthlalmologic exam, renal sonography) Rule out other medical etiologies (pheochromocytoma, Cushing’s syndrome)
     20  Preeclampsia-Initial Evaluation Serial blood pressure measurements Urine protein excretion Fetal monitoring Tests to rule out HELLP: Hematocrit, platelets, uric acid, alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactic dehydrogenase (LDH)
     21  Chronic Hypertension - Management Generally, deliver at term, unless superimposed preeclampsia, HELLP syndrome Avoid ACE inhibitors (renal failure, oligohydramnios, pulmonary hypoplasia, IUGR) and atenolol (IUGR)
     22  Preeclampsia-Management Seizure prophylaxis Blood pressure control Delivery
     23  Preeclampsia-Term Pregnancy Delivery is a short-term goal Induction of labor is appropriate after maternal-fetal observation/stabilization Cesarean reserved for standard obstetric indications Cesarean may be recommended in cases of severe preeclampsia where delivery is remote
     24  Preeclampsia-Preterm Pregnancy Mild preeclampsia - expectant management is acceptable under certain conditions Close maternal-fetal surveillance Ability to intervene either if conditions worsen or if acceptable gestational age reached In-hospital vs. home care?
     25  Preeclampsia-Preterm Pregnancy Severe preeclampsia - controversial Delivery for poor maternal condition is likely to be necessary over the short term Sibai has advocated expectant management for selected patients to attempt to reduce perinatal morbidity and mortality due to prematurity
     26  Preeclampsia-Preterm Pregnancy Expectant management of severe preeclampsia at preterm gestational age: Hospitalization Magnesium sulfate for seizure prophylaxis, at least during initial observation period Blood pressure control to range of 140-155/90-105 (labetalol or nifedipine) Daily assessment of maternal-fetal condition
     27  Preeclampsia-Preterm Pregnancy 24-34 weeks – corticosteroids for fetal lung maturation 24-32 weeks – ongoing daily surveillance if stable 33-34 weeks – deliver after 48 hours Deliver for HELLP syndrome, severe headache, uncontrolled hypertension, eclampsia
     28  Criteria for Expectant Management
     29  Magnesium Sulfate Zuspan identified magnesium as the primary agent in the treatment of eclampsia and suggested its use for the prevention of eclampsia Raises the seizure threshold Has a direct vascular relaxant effect, but is NOT an antihypertensive agent
     30  Magnesium Sulfate Given IV (most commonly) or IM 6 gram load followed by 2 grams per hour Therapeutic range 6-8 mg/dL Supratherapeutic levels lead to CNS depression, cardiac arrythmias, possible cardiac arrest (Mg level 15-20 mg/dL) Antidote - Calcium gluconate
     31  Magnesium Sulfate Continued until about 24 hours post-partum, depending on the patient’s condition While some argue the use of magnesium in mild preeclampsia, most authorities advocate its use in all women with preeclampsia
     32  Antihypertensive Therapy BP persistently over 160-170/110 warrants treatment Goal - 10-15% decrease (140-150/95-100) Overtreatment leads to uterine underperfusion and risk of fetal bradycardia