Hypertension in Pregnancy

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.

Categories

Chronic Hypertension Gestational Hypertension Preeclampsia Preeclampsia superimposed on

Chronic Hypertension

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)

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.

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.

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.

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

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.

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

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.

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

Evaluation of Hypertension in Pregnancy

History ID and Complaint HPI (S/S of

Preeclampsia) Past Medical Hx,

Past Family Hx Past Obstetrical Hx,

Past Gyne Hx Social Hx Medications,

Allergies Prenatal serology,

blood work Assess for

Hypertension in Pregnancy risk factors

Physical Vitals HEENT = Vision Cardiovascular Respiratory Abdominal =

Epigastric pain, RUQ pain

Neuromuscular and Extremities = Reflex, Clonus, Edema

Fetus = Leopold’s, FM, NST

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)

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

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

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!!!

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

Pregnancy Induced Hypertension

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

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*

Pregnancy Induced Hypertension

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

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

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

Mild vs. Severe Preeclampsia

Mild Severe

Systolic arterial pressure 140 mm Hg – 160 mm Hg ≥160 mm Hg

Diastolic arterial pressure 90 mm Hg – 110 mm Hg ≥110 mm Hg

Urinary protein <5 g/24 hrDipstick +or 2 +

≥5 g/24 hrDipstick 3+or 4+

Urine output >500 mL/24 hr ≤500 mL/24 hr

Headache No Yes

Visual disturbances No Yes

Epigastric pain No Yes

Etiology

Exact mechanism not known

• Immunologic• Genetic• Placental ischemia

• Endothelial cell dysfunction• Vasospasm• Hyper-responsive response to vasoactive hormones (e.g.

angiotensin II & epinephrine)

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

Pathophysiology

Pathophysiology

• Airway edema• Cardiac• Renal• Hepatic • Uterine

Upper airway edema

• Upper airway edema• Laryngeal edema• Airway obstruction

• Potential for airway compromise or difficulty in intubation

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

Hepatic

• Usually mild• Severe PIH or preeclampsia complicated by

HELLP periportal hemorrhagesischemic lesiongeneralized swellinghepatic swelling epigastric pain

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*

Uterine

• Activity increased• Hyperactive/hypersensitive to oxytocin• Preterm labor – frequent• Uterine/placental blood flow – decreased by 50-

70%• Abruption – incidence increased

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)

Morbidity / Mortality

Fetal complications:

• Abruptio placentae• IUGR• Premature delivery • Intrauterine fetal death

HELLP Syndrome

• Hemolysis• Elevated Liver enzymes• Low Platelets

• < 36 wks• Malaise (90%), epigastric pain (90%), N/V (50%)• Self-limiting • Multi-system failure

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

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

Controlling the HTN

• Hydralazine• Labetalol• Nitroglycerin• Nifedipine• Esmolol• Na Nitroprusside – risk of cyanide toxicity in the

fetus

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

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

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

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

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. “

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

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

• Enhanced sensitivity to non-depolarizing muscle relaxants

• MgSO4 blunts response to vasconstrictors and inhibits catecholamine release after sympathetic stimulation

Thank You!