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Hypertensive Disorders With Pregnancy. Amr Nadim, MD Professor of Obstetrics & Gynecology Ain Shams Maternity and Women’s Hospital [prof.amrnadim@gmail.com].
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Hypertensive Disorders With Pregnancy Amr Nadim, MD Professor of Obstetrics & Gynecology Ain Shams Maternity and Women’s Hospital [prof.amrnadim@gmail.com]
C.G. is a 39 year old married white female gravida 2, para 0, with one spontaneous abortion who presented for prenatal care at 14 weeks gestation. Blood pressure at that time was 130/80. The patient had no significant medical history and her gynecologic history was significant only for oral contraceptive use several years ago. The patient noted that her physician stopped the birth control pills after only two cycles, but the patient was not told why. • The pregnancy had been unremarkable until approximately one month ago when the patient noted increased swelling of her hands and feet. A 6 Kg. weight gain in two weeks time was noted. Blood pressure at that time was 124/78. There was no urinary protein. On the day prior to admission, at 28 weeks, the patient presented with a blood pressure of 160/98 and had been sent home to bedrest with instructions to take a single baby aspirin daily. On the day following, the patient was noted at home to have a persistent blood pressure of 180/100.
Avant propos… • Complicates 7-10% of pregnancies • 70% Preeclampsia-eclampsia • 30% Chronic hypertension • Eclampsia 0.05% incidence • 20% of Maternal Deaths • Cause of 10% of Preterm birth • Etiology unknown
Young female 3 fold increased risk • African American 2 fold increased risk • Multifetal pregnancies • Twins • Triplets • Hypertension • Diabetes Mellitus • Renal Disease • Collagen Vascular Disease
Hypertension during Pregnancy: Classification • Pregnancy-induced hypertension • Hypertension without proteinuria/edema • Preeclampsia • mild • severe • Eclampsia • Coincidental HTN: preexisting or persistent • Pregnancy-aggravated HTN • superimposed preeclampsia • superimposed eclampsia • Transient HTN: occurs in 3rd trimester, mild
Preeclampsia: Definition • Hypertension • > 140/90 • relative no longer considered diagnostic • Proteinuria • > 300 mg/24 hours or 1or 2+ on urine dipstick • may occur late • Edema (non-dependent) • so common & difficult to quantify it is rarely evoked to make or refute the diagnosis
SBP > 160 mm Hg DBP > 110 mm Hg Proteinuria > 5 g/24 hr. or 3-4+ on dipstick Oliguria < 500 cc/24 hr. serum creatinine Pulmonary edema or cyanosis CNS symptoms (HA, vision changes) Abdominal (RUQ) pain Any feature of HELLP hemolysis liver enzymes thrombocytopenia IUGR or oligohydramnios Criteria for Severe Preeclampsia
Preeclampsia: Risk Factors • Nulliparity (or, more correctly, primipaternity) • Chronic renal disease • Angiotensinogen gene T235 • Chronic hypertension • Antiphospholipid antibody syndrome • Multiple gestation • Family or personal history of preeclampsia • Age > 40 years • African-American race • Diabetes mellitus
Etiology and Prevention • Etiology is unknown. • Many theories: • genetic • immunologic • dietary deficiency (calcium, magnesium, zinc) • supplementation has not proven effective • placental source (ischemia)
Etiology and Prevention • A major underlying defect is a relative deficiency of prostacyclin vs. thromboxane • Normally (non-preeclamptic) there is an 8-10 fold in prostacyclin with a smaller in thromboxane • prostacyclin salutatory effects dominate • vasodilation, platelet aggregation, uterine tone • In preeclampsia, thromboxane’s effects dominate • thromboxane (from platelets, placenta) • prostacyclin (from endothelium, placenta)
Preeclampsia Prophylaxis: Aspirin • Aspirin has been extensively studied as a targeted therapy to thromboxane production • CLASP study, A multicenter RCT [CLASP Collaborative Group, Lancet 1994;343:619-29] • 9364 women, risk factors for PIH or IUGR or who had PIH or IUGR • 60 mg ASA daily vs. placebo • Small reduction (12%) in occurrence of PIH • Small reduction in preterm deliveries: 20 vs 22% • No difference in neonatal outcome
Preeclampsia Prophylaxis: Aspirin • NIH study of high-risk patients, RCT, 60 mg aspirin daily vs. placebo [Caritis, et al., N Engl J Med 1998;338:701-5] • pre-gestational DM (471 patients) • chronic hypertension (774 patients) • multifetal gestations (688 patients) • prior history of preeclampsia (606 patients) • No reduction in development of preeclampsia in any subgroup or groups in aggregate • No difference in perinatal death, preterm delivery, IUGR, maternal or fetal hemorrhagic complications
Preeclampsia: Mechanism • At this time the most widely accepted proposed mechanism for preeclampsia is: Global Endothelial Cell Dysfunction • Endothelial cell dysfunction is just one manifestation of a broader intravascular inflammatory response • present in normal pregnancy • excessive in preeclampsia • Proposed source of inflammatory stimulus: placenta
Pathophysiology Of importance, and distinguishing preeclampsia from chronic or gestational hypertension, is that preeclampsia is more than hypertension; it is a systemic syndrome, and several of its “non-hypertensive” complications can be life-threatening when blood pressure elevations are quite mild.
Pathophysiology: Cardiovascular • In severe preeclampsia, typically hyperdynamic with normal-high CO, normal-mod. high SVR, and normal PCWP and CVP. • Despite normal filling pressures, intravascular fluid volume is reduced (30-40% in severe PIH) • Variations in presentation depending on prior treatment and severity and duration of disease • Total body water is increased (generalized edema)
Pathophysiology: Cardiovascular • Preeclamptic patients are prone to develop pulmonary edema due to reduced colloid oncotic pressure (COP), which falls further postpartum: Colloid oncotic pressure: Antepartum Postpartum Normal pregnancy: 22 mm Hg 17 mm Hg Preeclampsia: 18 mm Hg 14 mm Hg
Pathophysiology • Respiratory: • Airway is edematous; use smaller ET tube (6.5) • risk of pulmonary edema; 70% postpartum • Renal: • Renal blood flow & GFR are decreased • Renal failure due to plasma volume or renal artery vasospasm • Proteinuria due to glomerulopathy • glomerular capillary endothelial swelling w/subendothelial protein deposits • Renal function recovers quickly postpartum
Pathophysiology: Hepatic • RUQ pain is a serious complaint • warrants imaging, especially when accompanied by liver enzymes • caused by liver swelling, periportal hemorrhage, subcapsular hematoma, hepatic rupture (30% mortality) • HELLP syndrome occurs in ~ 20% of severe preeclamptics.
Pathophysiology • Coagulation: • Generally hypercoagulable with evidence of platelet activation and increased fibrinolysis • Thrombocytopenia is common, but fewer than 10% have platelet count < 100,000 • DIC may occur, • Acutely esp. with placental abruption • Neurologic: • Symptoms: headache, visual changes, seizures • Hyperreflexia is usually present • Eclamptic seizures may occur even w/out BP • Possible causes: hypertensive encephalopathy, cerebral edema, thrombosis, hemorrhage, vasospasm
Hypertension during Pregnancy: Classification • Pregnancy-induced hypertension • Hypertension without proteinuria/edema • Preeclampsia • mild • severe • Eclampsia • Coincidental HTN: preexisting or persistent • Pregnancy-aggravated HTN • superimposed preeclampsia • superimposed eclampsia • Transient HTN: occurs in 3rd trimester, mild
Classification • Chronic hypertension • Preeclampsia-eclampsia • Preeclampsia Superimposed upon chronic hypertension or Renal Disease • Gestational hypertension (only during pregnancy) • Transient hypertension (only after pregnancy)
Chronic Hypertension Defined as hypertension diagnosed • Before pregnancy • Before the 20th week of gestation • During pregnancy and not resolved postpartum
Gestational Hypertension • Gestational Hypertension: • Systolic >140 • Diastolic>90 • No Proteinurea • 25% Develop Pre-eclampsia
Gestational Hypertension Diagnosis of gestational hypertension: • Detected for first time after midpregnancy • No proteinuria • Only until a more specific diagnosis can be assigned postpartum If: • BP returns to normal by 12 weeks postpartum, diagnosis is transient hypertension. • BP remains high postpartum, diagnosis is chronic hypertension. • Proteinurea develops Superimposed Preeclampsia is diagnosed (25% incidence)
Preeclampsia-Eclampsia • Occurs after 20th week (earlier with trophoblastic disease) • Increased BP (gestational BP elevation) with proteinuria • ‘LL’ Edema is NOT part of this definition
Diagnosis of Preeclampsia-Eclampsia • Gestational Hypertension: • Systolic >140 • Diastolic>90 • Proteinuria is defined as urinary excretion • 0.3 g protein or greater in a 24-hour • +2 or greater on urine dip specimen
Blood Pressure Measurement How would you measure the Blood Pressure for a pregnant lady?
Preeclampsia-Eclampsia • Blood pressure • Measure blood pressure • in the sitting position, • with the cuff at the level of the heart. • Inferior vena caval compression by the gravid uterus while the patient is supine can alter readings substantially, leading to an underestimation of the blood pressure. • Blood pressures measured in the left lateral position similarly may yield falsely low values if the blood pressure is measured in the higher arm and the cuff is not maintained at heart level. • Allow women to sit quietly for 5-10 minutes before measuring the blood pressure.
Blood Pressure Assessment:Patient preparation and posture Standardized technique: Patient 1. No caffeine in the preceding hour. 2. No smoking or nicotine in the preceding 15-30 minutes. 3. No use of substances containing adrenergic stimulants such as phenylephrine or pseudoephedrine (may be present in nasal decongestants or ophthalmic drops). 4. Bladder and bowel comfortable. 5. Quiet environment. Comfortable room temperature. 6. No tight clothing on arm or forearm. 7. No acute anxiety, stress or pain. 8. Patient should stay silent prior and during the procedure.
Blood Pressure Assessment:Patient preparation and posture Standardized technique: Posture • The patient should be calmly seated for at least 5 minutes, with his or her back well supported and arm supported at the level of the heart. His or her feet should touch the floor and legs should not be crossed. • The patient should be instructed not to talk prior and during the procedure.
Standardized technique: Use a mercury manometer or a recently calibrated aneroid or a validated electronic device. Aneroid devices should only be used if there is an established calibration check every 6-12 months. Recommended Technique for Measuring Blood Pressure
Electronic oscillometric devices: Use a validated electronic device according to BHS, AAMI or IP standards. For self blood pressure measurement devices, a logo on the packaging ensures that this type of device and model meets the international standards for accurate blood pressure measurement. Office Home / Self Recommended Technique for Measuring Blood Pressure AAMI=Association for the Advancement of Medical Instrumentation; BHS=British Hypertension Society; IP: International Protocol.
Recommended Technique for Measuring Blood Pressure (cont.) • Select a • cuff with the appropriate size
Locate brachial and radial pulse Position cuff at the heart level Arm should be supported Recommended Technique for Measuring Blood Pressure (cont.)
To exclude possibility of auscultatory gap, increase cuff pressure rapidly to 20-30 mmHg above level of disappearance of radial pulse Place stethoscope over the brachial artery Recommended Technique for Measuring Blood Pressure (cont.)
Drop pressure by 2 mmHg / sec Appearance of sound (phase I Korotkoff) = systolic pressure Record measurement Drop pressure by 2 mmHg / beat Disappearance of sound (phase V Korotkoff) = diastolic pressure Record measurement Take 2 blood pressure measurements, 1 minute apart Recommended Technique for Measuring Blood Pressure (cont.)
Korotkoff sounds 200 No sound 180 Clear sound Phase 1 160 Muffling Phase 2 Auscultatory gap No sound 140 120 Muffled sound Phase 3 100 Muffled sound Phase 4 80 60 Possible readings: No sound Phase 5 40 184 / 100 136 / 100 20 184 / 86 = correct 136 / 86 0 mm Hg Recommended Technique for Measuring Blood Pressure (cont.) Systolic BP Diastolic BP
Preeclampsia-Eclampsia • Blood pressure • Record Korotkoff sounds I (the first sound) and V (the disappearance of sound) to denote the systolic blood pressure (SPB) and DPB, respectively. • In about 5% of women, an exaggerated gap exists between the fourth (muffling) and fifth (disappearance) Korotkoff sounds, with the fifth sound approaching zero. In this setting, record both the fourth and fifth sounds (eg, 120/80/40 with sound I = 120, sound IV = 80, sound V = 40).
Recommended Technique for Measuring Blood Pressure • Standardized technique: • For initial readings, take the blood pressure in both arms and subsequently measure it in the arm with the highest reading. • Thereafter, take two measurements on the side where BP is highest.
Recommended Technique for Measuring Blood Pressure (cont.) Record the blood pressure to the closest 2 mmHg on the manometer as well as the arm used and whether the patient was supine, sitting or standing.
Recommended Technique for Measuring Blood Pressure (cont.) • Avoid digit preference for five (5) or zeros (0) by not rounding up or down. • Record the heart rate.
Recommended Technique for Measuring Blood Pressure (cont.) • The seated blood pressure is used to determine and monitor treatment decisions. • The standing blood pressure is used to test for postural hypotension, if present, which may modify the treatment.
Blood Pressure Assessment:Patient preparation and posture Standing position For patients over age 65, diabetics and patients being treated with antihypertensives, check if there are postural changes while taking blood pressure reading, i.e. after one to five minutes in the standing position and under circumstances when the patients complains of symptoms suggestive of hypotension.
Classification of Preeclampsia-Eclampsia • Mild Pre-eclampsia • Severe Pre-eclampsia
Classification of Preeclampsia-Eclampsia • Criteria for Severe Preeclampsia (one or more) • Blood Pressure: >160 systolic, >110 diastolic • Proteinurea: >5gm in 24 hours, over 3+ urine dip • Oligurea: less than 400ml in 24 hours • CNS: Visual changes, headache, scotomata, mental status change • Pulmonary Edema • Epigastric or RUQ Pain: Usually indicates liver involvement
Classification of Preeclampsia-Eclampsia • Criteria for Severe Preeclampsia (one or more) • Impaired Liver Function tests • Thrombocytopenia: <100,000 • Intrauterine Growth Restriction: With or without abnormal doppler assessment • Oligohydramnios