Hypertensive Disorders of Pregnancy

Family Medicine Specialist ProgramCME

Case

A 32 year-old G2P1 woman presents for her routine ante-natal visit at 32 weeks’ gestation. Her BP is 140/90. Throughout her pregnancy to date her BP has ranged from 115/75 to 130/85. Her weight is 105 kg.

What steps do you perform as part of your initial investigation?

Case - continued

Repeated blood pressures over the next three hours range from 140/90 to 155/95.

What is your management plan?

Objectives• Describe the classification of hypertension in

pregnancy.• Discuss the appropriate monitoring and

management of hypertension in pregnancy and pre-eclampsia.

• Discuss how to determine the appropriate medication according to the condition of the woman.

• Describe a Quality Improvement project with regards to patients presenting with hypertension in pregnancy.

Classification of Hypertension

1. Pre-existing hypertension– With co-morbid conditions– With Pre-eclampsia• Resistant hypertension• New or worsening proeinuria• > 1 adverse conditions(s)

2. Gestational hypertension– With co-morbid conditions– With Pre-eclampsia• New or worsening proteinuria• > 1 adverse conditions(s)

Determining Blood Pressure

• Sitting position with arm at heart level• Appropriate size BP cuff• Accurate mercury sphygmomanometer• Repeat measurements in > 4 hour intervals

unless very high

Definitions

Hypertension• Diastolic BP of >90 mm Hg on 2 measurements > 5 minutes apart after a period of 10 minutes rest•Diastolic BP of > 110 mm Hg on a single measurement

Hypertension - Definition

• Pre-existing hypertension– Hypertension < 20 weeks gestation

• Gestational hypertension– Onset of hypertension > 20 weeks gestation

(includes preeclampsia)

Preeclampsia- Definition

• Hypertensive disorder of pregnancy– With pre-existing hypertension this means:• resistant hypertension• New/worsening proteinuria• One or more adverse conditions

– With gestational hypertension• New-onset proteinuria• One or more adverse conditions

Severe Preeclampsia - Definition

• Onset before 34 weeks gestation• Associated with heavy proteinuria – 3 – 5 gms per day

• With onset of one or more adverse conditions

Definition

• Proteinuria– Indicates glomerular dysfunction– Urine protein > +2 on dipstick– Urine protein > 200 mg/L on 24 hour collection or

urine protein/creatinine ratio > 0.03 on spot check– 24 hour urine analysis should be considered if

urine protein > +1 on dipstick

• Edema is NOT part of the definition

Preeclampsia Adverse Conditions (1)

• Vascular/Pulmonary– BP • sBP > 160 mm Hg• dBP > 110 mm Hg

– Pulmonary edema– Chest pain– Shortness of breath (dyspnea)

Preeclampsia Adverse Conditions (2)

• Renal– Oligouria– Elevated serum creatinine– Serum albumin <20 g/L

• Hepatic– Abdominal/epigastric/right upper quadrant pain– Severe nausea or vomiting– Elevated liver enzymes – AST, ALT, LDH

Preeclampsia Adverse Conditions (3)

• Central Nervous System– New or unusual headache– Seizures (eclampsia)– Visual disturbances

• HELLP Syndrome– Hemolysis– Elevated liver enzymes (AST, ALT, LDH)– Low platelet count

Preeclampsia Adverse Conditions (4)

• Hematological– Decreased platelets <100,000– Disseminated intravascular coagulopathy (DIC)

Hypertension & Fetal consequences

• Intrauterine growth restriction (IUGR)• Oligohydramnios• Placental abruption• Prematurity• Fetal compromise• Intrauterine fetal death

Incidence• 10% of all pregnancies complicated by

hypertension– one third of these will have proteinuria

• majority of preeclampsia in nulliparous patients– 2 to 5 %– Increased mortality risk in older gravidas– Increased risk in pregnancy with new partner

• multiparas have increased risk with preexisting hypertension, renal disease, diabetes mellitus

• preeclampsia is a leading case of direct maternal mortality

Preeclampsia Morbidity & Mortality

• Maternal– Stroke (sBP > 160 mm

Hg)– Pulmonary edema– Jaundice– Seizure (eclampsia)– Placental abruption– Acute renal failure

• Fetal– Oligohydramnios– Intrauterine growth

restriction (SGA)– Metabolic acidosis

• 5 minute APGARS <3• Requiring respiratory

ventilation at birth

– Fetal death

Assessment of woman - Clinical

• Blood Pressure– assess severity– ensure consistency in measuring– relationship of high BP to DIC not seizure

• Cardiorespiratory– chest pain– dyspnea– distended neck veins

Assessment of woman – Clinical (cont’d)

• Central Nervous System– presence and severity of headache– vision disturbances – blurring, scotomata– tremulousness, irritability, somnolence– hyperreflexia

• Hematologic– bleeding, petechiae

• Hepatic– RUQ and epigastric pain– nausea and vomiting

• Renal– urine output and colour

Assessment of woman - Laboratory• Hematologic– hemoglobin, platelets (HELLP), blood film– PTT, INR, fibrinogen, FDP– LDH (HELLP), uric acid, bilirubin

• Hepatic– ALT, AST (HELLP)– glucose and ammonia to rule out AFLP

• Renal– proteinuria– creatinine, urea, uric acid

Assessment of Fetus

• Fetal movement• Fetal heart rate assessment, by auscultation

or EFM• Fetal growth assessment by fundal height

measurement or ultrasound• Where resources exist:– Biophysical profile (BPP)– Amniotic fluid volume (AFV)

Maternal Stress Reduction

• Component of maternal BP is adrenergic• Maternal discomfort must be minimized• Several components

– well planned management protocol (team approach)

– clear explanation of plan to woman/family– quiet, dimly lit, isolated room– minimization of negative stimuli

Management of symptoms

• Nausea and vomiting– antiemetic of choice

• Maternal pain (headache, RUQ or epigastric pain)– morphine 2 – 4 mg IV– antacid– minimize palpation

Anti-hypertensive therapy - Goals

• minimize risk of maternal cerebro-vascular accident

• prevent placental abruption• gain time for further assessment and

treatment– stabilize for transfer to higher level facility, if

needed– facilitate vaginal delivery when possible– prolong gestation where appropriate/feasible

Anti-hypertensive agents

• Labetalol (Trandate®, Normodyne®)• Hydralazine (Apresoline®)• Nifedipine (Adalat-PA®)• Clonidine

Anti-hypertensive agents

Hydralzine• direct arteriolar vasodilator• rapid onset of action useful for hypertensive

crisis• can be used orally or via IV• should not be first choice due to high rate of

maternal/fetal adverse effects

Anti-hypertensive agents

Hydralzine (cont’d)Dosage:– 5 mg IV test dose, followed by 5 – 10 mg IV q 20

min.– infusion 0.5 – 10 mg/hourCaution: unpredictable hypotension with

resulting fetal compromiseSide Effects: flushing, headache, and maternal

tachycardia

Anti-hypertensive agents

Labetalol• Combined α and β-blocker with Intrinsic

Sympathetic Activity• Rapid onset of action useful for hypertensive

crisis• Can be used orally or via IV

Anti-hypertensive agents

LabetalolDosage: maximum 300 mg IV dose

– bolus 10 – 20 mg IV q 10 min. up to 300 mg– infusion 1 – 2 mg/min., increasing by 1 mg/ q 15

min. to a maximum of 4 mg/min. IB titrated to BP

Caution: asthmaSide Effects: fetal bradycardiaBenefits: dependable, familiar

Anti-hypertensive agents

Nifedipine• Calcium channel blocker• Direct relaxation of vascular smooth muscle• Oral agent• Not sub-lingual administration

Anti-hypertensive agents

NifedipineDosage:

– Adalat PA 10 mg bid may increase to 40 mg bid– Adalat XL starting dose 30 mg/day

Caution: magnesium toxicity (?) with use of Adalat and MgSO4 in combination

Side Effects: flushing, headache, palpitations, tocolysis

Anti-hypertensive agents

Clonidine• Potent α-2-adrenoceptor central stimulant• Used to treat mild and moderate

hypertensionDosage:

– 150 µg infused in normal saline– Per os: 0.1 mg to 0.2 mg twice a day

Side Effects: sedation, dry mouth

Seizures

• Blood pressure not a reliable predictor of who will have seizures

• No benefit to prophylaxis in absence of proteinuria

• High ‘number needed to treat’ to prevent seizure

• agents not innocuous nor completely effective• MgSO₄ is agent of choice when seizure

prophylaxis is felt to be indicated

Seizures – Possible complications

• Fetal bradycardia (more than 50%)• Placenta abruptio (10% to 20%)• Aspiration pneumonia (5% to 10%)• Cerebral hemorrhage, especially in the older

woman• Temporary loss of sigh with progressive recovery

within one week (10%)• Coma due to the cerebral edema (5%)• Psychosis that can last 2 weeks (less than 5%)

Seizures - Management

Magnesium sulfate (MgSO₄)– agent of choice for prophylaxis and termination of seizures– will control seizures within 1 to 2 hours– most woman will regain consciousness and orientation– Superior to phenytoin for prophylaxis– superior to phenytoin or diazepam in preventing

recurrence– decreased maternal morbidity and mortality with use for

cessation of seizure activity– no difference in perinatal mortality– should be on ‘essential drug list’ in every country

Seizures - Management

Magnesium sulfateLoading Dose:

– 4 g IV (20 ml of 20% solution) slowly over 20 min.– followed by 1 – 4 g / hour IV

OR– 5 g IM (10 ml of 50% solution) with 1 ml of 20%

lidocaine in same syringe twice, each side– followed by 5 g IM q 4 h

Seizures - Management

Magnesium sulfateSide Effects: weakness, paralysis, cardiac

toxicityMonitor: reflexes, respiration, level of

consciousnessCAUTION: Confirm the concentration of this

medication when calculating the dosage

Seizures - Management

Magnesium sulfateOverdose:• observe closely for possible side effects including

weakness, respiratory paralysis, somnolence• especially high risk in those with oliguria or those

receiving calcium channel blockersANTIDOTE• stop magnesium sulfate infusion• give calcium gluconate 1g IV (10 ml of 10%

solution) over 10 minutes

Seizures – Management protocols

Every labour and delivery unit should establish and post protocols for the use of magnesium sulfate.

Parameters should include:• Preparation of medication• Assessments required prior to administration• Administration protocol• Assessment for side effects• Management of toxicity• Documentation

Seizures – Differential diagnosis

When magnesium sulfate therapy fails to control seizures, consider other possible causes:• chronic epilepsy• encephalitis• meningitis• cerebral tumor• cerebral vascular malformation (aneurysm)• secondary cerebral abscesses due to parasitic or

fungal infections• severe malaria

Transport

• Consider transport only if local resources limited and maternal/fetal condition permits

• Stable maternal BP• Reassuring fetal status• Administer appropriate anti-hypertensive agents• Give MgSO₄, if appropriate• Consult with referral centre and woman/family• Woman should be transported on her left side,

accompanied by skilled birth attendant

Delivery – “The Cure”• Timely delivery minimizes maternal and neonatal

morbidity and mortality• Optimize maternal status before interventions to

deliver• Delay delivery to gain fetal maturity and to allow

transfer only when maternal and fetal condition permit

• Gestational hypertension is a progressive disease, expectant management is potentially harmful in presence of severe disease or suspected fetal compromise

When to deliver

≥37 weeks with gestational hypertension≥34 weeks with severe gestational hypertension<34 weeks with any of:

– poorly controlled diastolic BP– laboratory evidence of worsening end-organ

involvement– suspected fetal compromise– uncontrolled seizures– symptoms unresponsive to appropriate therapy

Management - Overview

• stress reduction (helps in 50% of cases)• clinical and laboratory assessment of mother and fetus• treat blood pressure if diastolic BP ≥ 110 mmHg• treat nausea and vomiting, and other symptoms

including pain effectively• consider seizure prophylaxis• consider timing and mode of delivery (induction)• consider transfer to referral center, if applicable• closely monitor the woman in the early post-partum

Case:

A 32 year old G2P1 woman presents for her routine prenatal visit at 32 weeks’ gestation. Her blood pressure is 140/90. In the past, throughout her pregnancy it has been 115/75 to 130/85. Her weight is 105 kg.

What steps do you perform as part of your initial investigation?

Case:

• Repeat measurement in ≥ 4 hour intervals unless very high

• Assess for proteinuria (urine dip stick)• Question woman about any signs and

symptoms of gestational diabetes• Order initial blood work: (liver function test,

uric acid, platelets)

Case (cont’d)

Repeat blood pressures over the next three hours range from 140/90 to 155/95

Urine dip stick: 3+What is your management plan?

Case:

• Delivery is the cure• Monitor blood pressure and control with

medications if necessary• Monitor fetal well being

Key Messages

• Health care providers must be able to promptly recognize the various presentations of hypertension in pregnancy.

• Health care providers must be able to identify appropriate monitoring and management of gestational hypertension, including having a plan for referral and transfer to a higher-level health care facility when needed.

Key Messages (cont’d)

• Health care providers must be able to take emergency measures to stop seizure activity, and to stabilize the woman.

• Magnesium sulfate is a cost effective and life-saving drug. Health care providers must advocate with national health authorities to ensure a continuous and an uninterrupted supply of this medication as part of their safe motherhood programs.