Hypertension in Pregnancy

OBJECTIVES List criteria for the diagnosis of preeclampsia List criteria for the diagnosis of severe preeclampsia/HELLP syndrome Discuss current management considerations

Hypertension Sustained BP elevation of 140/90 or greater Proper cuff size Measurement taken while seated Use 5th Korotkoff sound

Forms of HTN in Pregnancy Gestational Hypertension Formerly called Pregnancy-Induced Hypertension No proteinuria

Forms of HTN in Pregnancy Gestational Hypertension Preeclampsia Hypertension with proteinuria May have other evidence of end-organ disease Edema Visual changes Headache Epigastric pain Laboratory changes

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

Patient Categories 25%

Forms of HTN in Pregnancy Gestational Hypertension Preeclampsia Chronic Hypertension As a group these occur in 12 to 22% of pregnant patients and are directly responsible for approximately 18% of maternal mortality nationally.

Chronic Hypertension Pre-existing hypertension Hypertension before 20 weeks in the absence of gestation If hypertension persists beyond 6 weeks postpartum

Preeclampsia Hypertension after 20 weeks of gestation Proteinuria- 300mg Edema

Preeclampsia Hypertension after 20 weeks of gestation Proteinuria- 300mg Edema BP > 160 systolic or >110 diastolic 5grams of protein in 24 hour urine Oliguria Cerebral of visual distrubances Pulmonary edema or cyanosis Epigastric or RUQ pain Impaired liver function Thrombocytopenia IUGR

Risk Factors FACTOR RISK RATIO Nulliparity 3:1 Age > 40 African American 1.5:1 Chronic hypertension 10:1 Renal disease 20:1 Antiphospholipid syndrome

Risk Factors FACTOR RISK RATIO Family history of PIH 5:1 Diabetes mellitus 2:1 Twin gestation 4:1

Prevention Low dose ASA ineffective in patients at low risk Calcium supplementation is ineffective (2.0 g of calcium gluconate per day) No compelling evidence that either are harmful Recent study done with antioxidant (1,000mg VitC and 400mg VitE). Small study that needs to be confirmed.

Cardiovascular Effects Hypertension Increased cardiac output Increased systemic vascular resistance Hypovolemia

Neurologic Effects Seizures-eclampsia Headache Cerebral edema Hyper-reflexia

Pulmonary Effects Capillary leak Reduced colloid osmotic pressure Pulmonary edema

Hematologic Effects Volume contraction Elevated hematocrit Low platelets Anemia due to hemolysis

Renal Effects Decreased glomerular filtration rate Increased BUN/creatinine Proteinuria Oliguria Acute tubular necrosis

Fetal Effects Increased perinatal morbidity Placental abruption Fetal growth restriction Oligohydramnios Fetal distress

Severe Preeclampsia BP > 160-180 systolic or 110 diastolic Proteinuria > 5 g per day Pulmonary edema Oliguria Elevated liver enzymes Low platelets Growth restriction Decreased AFV Headache Epigastric pain

Management The ultimate cure is delivery Assess gestational age Assess cervix Fetal well-being Laboratory assessment Rule out severe disease!!

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

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

Indications for Delivery Worsening BP Nonreassuring fetal condition Development of severe PIH Fetal lung maturity Favorable cervix

Unfavorable Cervix No contraindication to prostaglandin agents If < 32 weeks, consider cesarean When favorable, oxytocin

Hypertensive Emergencies Fetal monitoring IV access IV hydration The reason to treat is maternal, not fetal May require ICU

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

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

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

Acute Medical Therapy Hydralazine Labetalol Nifedipine Nitroprusside Diazoxide Clonidine

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

Labetalol Dose: 20mg, 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 block

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

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

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

Seizure Prophylaxis Magnesium sulfate 4-6 g bolus 1-2 g/hour Monitor urine output and DTR’s With renal dysfunction, may require a lower dose

Magnesium Sulfate Is not a hypotensive agent Works as a centrally acting anticonvulsant Also blocks neuromuscular conduction Serum levels: 6-8 mg/dL

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 v over 3 minutes

Treatment of Eclampsia Few people die of seizures Protect patient Avoid insertion of airways and padded tongue blades IV access MGSO4 4-6 bolus, if not effective, give another 2 g

THE FIRST THING TO DO AT A SEIZURE IS TO TAKE YOUR OWN PULSE!

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

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

Other Complications Pulmonary edema Oliguria Persistent hypertension DIC

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

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

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

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

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

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

HELLP Syndrome He-hemolysis EL-elevated liver enzymes LP-low platelets

HELLP Syndrome Is a variant of severe preeclampsia Platelets < 100,000 LFT’s - 2 x normal May occur against a background of what appears to be mild disease

Conservative Management Controversial Steroids Requires tertiary care Must have stable labs and reassuring fetal status May use antihypertensives

SUMMARY Criteria for diagnosis Laboratory and fetal assessment Magnesium sulfate seizure prophylaxis Timing and place of delivery