Hypertensive Disorders Of Pregnancy

HYPERTENSIVE DISORDERS OF PREGNANCY

BY DR. JAMES E. OMIETIMI DEPART. OF OBSTETRICS & GYNAECOLOGY UPTH, PORT HARCOURT

INTRODUCTION Spectrum of disorders including Pre-Eclampsia, Eclampsia, Chronic hypertension (either essential or secondary to renal disease, endocrine disease, or other causes), Chronic hypertension with superimposed Pre-Eclampsia, and Gestational hypertension. 2nd commonest indication for admission into the ANW after prolonged pregnancy worldwide and here in UPTH was found to be the commonest in the year 2003. Accounted for 88 out of 588 (14.5%) of admissions into ANW in the year 2003. Annual Report.

CLASSIFICATION

PREGNANCY INDUCED HYPERTENSION -PIH (without proteinuria) -PIP (without hypertension) -Pre-Eclampsia CHT and CRD CHT (without proteinuria) CRD (proteinuria and hypertension) CHT with superimposed PE CHT due to endocrine disease Cushing’s Dx. & Syndrome Primary Hyperaldosteronism Thyrotoxicosis Pheochromocytoma Acromegaly CHT due to coarctation of the aorta

PRE-ECLAMPSIA AND ECLAMPSIA

Pre-Eclampsia is a multisystem disorder of unknown aetiology and unique to pregnant women after 20 weeks gestation. It is a progressive disease with a very variable mode of presentation and rate of progression. It is pregnancy specific with reduced organ perfusion secondary to vasospasm and endothelial calsification. Pre-Eclampsia is said to complicate 5% of all deliveries. It is said to affect 5.8% of primigravidae and 0.4% of secundagravidae.

RISK FACTORS; • parity, • race, • multiple gestations, • environmental factors, • maternal age, • maternal size • history of chronic hypertension

Definition and Diagnosis

Pre-Eclampsia can not be accurately defined until its cause is known. It is described as a syndrome comprising of hypertension and proteinuria, +/- edema occurring after 20 weeks gestation. Hypertension -140/90 mm of Hg or more on at least two occasions four hours or more apart after the 20th week of pregnancy in a woman known to be normotensive and in whom blood pressure returns to normal by the sixth postpartum week. Proteinuria is defined as the excretion of 0.3 g protein or more within 24 Hr or a measurement of 1+ or more using reagent strips.

Classification This is classified as mild or severe forms as the latter is associated with increased maternal and fetal morbidity. Severe form is said to occur if one or more of the conditions in the table are present.

Definition of severe pre-eclampsia 1. Arterial pressure > 160mmHg systolic or > 110mmHg diastolic on two occasions at least 6 hrs apart. 2. Proteinuria > 5g in 24 hour > 3 + urine dipstick 3. Oliguria < 400 ml of urine in 24 h 4. Cerebral signs – headache, blurred vision or altered consciousness 5. Pulmonary oedema or cyanosis 6. Epigastric or right upper quadrant pain 7. Impaired liver function 8. Hepatic rupture 9. Thrombocytopenia 10. HELLP Syndrome

Hypertensive Disorders During Pregnancy: Indications of Severity Abnormality

Mild

Severe

Diastolic blood pressure

< 100 mg Hg

110mmHg or higher

Proteinuria

Trace to 1 +

Headache

Absent

Present

Visual disturbances

Absent

Present

Upper abdominal pain

Absent

Present

Oliguria

Absent

Present

Convulsion

Absent

Present (eclampsia)

Serum creatinine

Normal

Elevated

Thrombocytopenia

Absent

Present

Liver enzyme elevation

Minimal

Marked

Fetal growth restriction

Absent

Obvious

Pulmonary edema

Absent

Present

Persistent 2 + or more

Material Vascular Disease

Faculty Placentation

Excessive Trophoblast

Genetic Immunologic or Inflammatory Factors Reduced Uteroplacental Perfusion Vasoactive Agents: Prostaglandins Nitric Oxide Endothelins

Noxious Agents: Cytokines Lipid Peroxidases Endothelial Activation Capillary Leak

Vasospasm

Activation of Coagulation Edema

Proteinuria Hemoconcentration

Hyper tension

Oliguria

Seizures

Liver Ischemia

Abruption

Thrombo cytopenia

Pathophysiology The summary is that as a result of the damage to the endothelial cells, it looses its functions and in addition also produces pro-coagulants, vasoconstrictions and mitogens. The increased pressor sensitivity of the maternal vessels leads to profound vasospasm and reduced organ perfusion which are characteristic of this disorder.

COMPLICATIONS OF PRE-ECLAMPSIA

et

FETUS  IUGR, Preterm delivery, Abruptio placenta, IUFD MATERNAL Kidneys - Proteinuria, ↓ GFR, ↑ Plasma Creatinine Cardiovascular - ↓ Plasma Volume, ↓ CVP, AP ↑ & SVR - Glomerular endothehosis  Renal failure (ATN, Cortical necrosis)   Contractility usually unchanged. Brain-

HT encephatopathy, ischaemia and infarction, vasospasm, Haemorrhage, Oedema, Eclampsia

Liver

- Altered LFT, Periportal hepatic necrosis, Subcapsulaar haemorrhage, FDP, HELLP.

Lungs-

Leaking Capillaries  pulmonary Oedema, ARDS

Coagulation

-Thrombocytopenia

(↑ Platelet activation and consumption)

Prediction and Prevention No ideal predictive tests that fulfil all described criteria.Two most important predictive factors: 1. Nulliparity - Pre-Eclampsia in 5.8% primigravida, 0.4% Secundagravida. 2. Family History - Considerable evidence support significant genetic contribution Aetiology & pathophysiology are still not understood fully and this has hindered development of effective preventive measures. . Anti-platelet therapy -Low dose Aspirin . Calcium Supplementation

INVESTIGATIONS Urinalysis, urine m/c/s FBC Clotting time Serum E/U/Cr + Uric acid LFTs Biophysical profile Ultrasound measurement of AC

TREAT MENT Delivery is the cure for Pre-Eclampsia. The prime objective is to prevent convulsion. The management ideally should be multidisciplinary. It is based on the severity of the disease and also influenced by gestational age.

Management should include;

1. Treatment of hypertension The risk of cerebral haemorrhage is a major cause of maternal deaths (60%) Significant risk of CVA occurs when MAP > 140mmHg (180/120). The aim of treatment is to prevent intracerebral haemorrhage while not affecting uteroplacental blood flow and maternal renal functions.

Prolonged treatment of HT is advisable when the fetus is immature in an attempt to delay delivery. However, this can only be undertaken provided the mother is not placed at risk and that strict monitoring of both the mother and the fetus is carried out at frequent regular intervals, hospitalization and bed rest may be all that is required in some patients.

Antihypertensive therapies Acute therapy-hydrallazine, labetalol Prolonged therapy-methyldopa, nifedipine, hydralazine ACE inhibitors not recommended Diuretics not recommended except in pulmonary edema

For Severe Pre-Eclampsia Anticonvulsant-Mg-Sulphate, Diazepam Antihypertensives - Follow by Delivery Conservative management in severe cases – Need to be cautious. Maternal safety is paramount.

MANAGEMENT IN HOSPITAL 1. Detailed examination followed by daily scrutiny for clinical findings such as headache, visual disturbances, epigastric pain, and rapid weight gain. 2. Weight on admittance and every alternate day thereafter. 3. Analysis for proteinuria on admittance and daily ward urinalysis 4. Blood pressure readings in sitting position with an appropriate-size cuff every 4 hours, except between midnight and morning. 5. Measurement of plasma or serum creatinine, uric acid, hematocrit, platelets, and serum liver enzymes, the frequency to be determined by the severity of hypertension. 6. Frequent evaluation of fetal size and amnionic fluid

ECLAMPSIA Eclampsia is defined as the new onset of convulsions, before or during pregnancy or post partum, unrelated to other cerebral pathologic conditions in a woman with Pre-Eclampsia. Incidence Reported rate 1:2000 to 1:3000 deliveries. The incidence is significantly higher in non industrialized nations. Estimates in developing countries varies from 1 in 100 to 1 in 1700. Worldwide of estimated 500,000, maternal deaths every year – 10 – 15% are associated with HDP. Reported maternal mortality rates varies from 0.5% in US to 20%, perinatal mortality from 10% to 28%

Management Aim

1. Stop Convulsions and prevent recurrence 2. Control the blood pressure 3. Avoidance of diuretics and limitation of fluid administration 4. Correct fluid and electrolyte imbalance 5. Deliver the patient in the fastest possible

Anticonvulsants - Diazepaml - Phenytoin - Chlomethiazole - Magnesium sulphate The anticonvulsant therapy should protect the woman and her fetus from deleterious effects of convulsion but should not expose either to additional risks from the therapy.

Supportive Management

Airways - Nasogastric tube - Oxygen - Catheterization / Urinary output monitoring - Tepid sponge / Expose to fan - Management of an unconscious patients. -

Complications Pulmonary Oedema - Renal and hepatic failiure - Hemiplegia - Altered Consciousnes / Coma - Some degree of Blindness - Psychoses -