Valerie Hill - Hypertension

Leading cause of maternal and perinatal morbidity and mortality in the world.

Hypertensive Disorders

Three most common types of hypertensive disorders in pregnancy

Three most common types are chronic hypertension, gestational hypertension and pre-eclampsia/eclampsia

Non Severe Hypertension

• BP > 140/90 taken at 2 measurements at least 15 mins apart.

• MAP >105mmHg.

• FHR may be abnormal. Placental perfusion may be reduced with oligohydraminos. Premature placental aging not apparent.

• Treated with antihypertensives to bring DBP down to 85 to reduce risk of severe HTN. Labetelol is the antihypertensive of choice.

Severe Hypertension

• BP > 160/110 taken at 2 measurements at least 15 mins apart.

• MAP >105mmHg.

• Obstetrical emergency requiring immediate treatment. FHR may be abnormal. Placental perfusion is decreased presenting as IUGR. FHR may show decels in late labour. At birth the placenta appears smaller than normal with premature aging apparent. Ischemic necroses (white) and intervillous fibrin deposition (red) appear.

Chronic Hypertension

• Predates the pregnancy or appears before 20 weeks.

• Can occur with comorbid conditions such as DM or kidney disease, which requires tighter BP control. 

Gestational Hypertension

• HTN that appears for the first time at or after 20 weeks gestation.

• Comorbid conditions such as DM or kidney disease, which requires tighter BP control.

Pre-eclampsia

• HTN (chronic or gestational), accompanied by new-onset proteinuria (conc of 0.03g/L+ in at least 2 random urine speciments collected at least 6 hours apart with no UTI. In a 24 hour specimen it is 0.3g/L+.) and/or one or more adverse conditions or severe complications.

• Onset after 20 weeks gestation.

• In chronic HTN, pre-eclampsia is known as superimposed pre-eclampsia, and presents with the same symptoms as normal pre-eclampsia but may also present with resistant HTN (meaning HTN that requires 3+ meds).

PIERS Model (7 things tested)

Assessment data collected from a pre-eclampsia patient in the first 48 hours of hospitalization to determine the risk of severe adverse effects. Gestational age, presence of chest pain or dyspnea, o2sat, platelet count, creatinine and AST are recorded into the model.

Urine Dipstick Measurements (0, trace, +1-4)

• 0 - negative

• Trace - trace

• +1 - 0.3g/L

• +2 - 1g/L (strongly suggests 0.3g/day)

• +3 - 3g/L

• +4 - 10+g/L

Patho of Pre-Eclampsia

• Abnormally thick walled muscular vessels with higher resistance. The spiral maternal blood vessels may also have a lesion called acute atherosis which looks like early atherosclerosis. Placental perfusion is decreased, resulting in hypoxia and endothelial damage

• Interferes with normal adaptations of pregnancy (more blood, vasodilation, decreased resistance, increased cardiac output)

• The main pathogenic factor of pre-eclampsia is NOT high BP, but instead is poor perfusion as a result of vasospasm. When the arteries vasospasm, it diminishes the diameter of the BVs, causing poor perfusion and therefore the increase in BP. 

HELLP Syndrome

Severe pre-eclampsia accompanied by hemolysis (H), elevated liver enzymes (EL) and low platelets under 100x10⁹ (LP). Mortality can be as high as 25%. Mostly seen in older white multiparous patients.

Symptoms of HELLP

Symptoms include malaise, RUQ pain, N&V.

Patho of HELLP

• The pathophysiology of HELLP is that when arteries vasospasm, fibrin is deposited in BVs and platelets adhere to BVs. As RBCs pass through the narrow BVs they break (hemolysis), which contributes to the low platelet and RBC counts we see.

• At the same time, the deposits in liver BVs impair its function and cause elevated liver enzymes from damaged hepatic tissue. 

6 Preventions of Pre-Eclampsia in low risk pts

• Abstain from alcohol and smoking

• Folate

• Calcium

• Exercise

• Patients at high risk should take low-dose aspirin (81mg)

• There is no reliable screening for pre-eclampsia.

Transient Hypertension

•  Elevated BP due to normal environmental stimuli

White Coat Hypertension

BP that is elevated in the clinicians office (>140/90) but is consistently normal outside of it (<135/85)

Masked hypertension

BP that is consistently normal in the clinicians office (<140/90) but is consistently higher outside of it (>135/85).

Eclampsia

• Characterized by seizures from the effects of pre-eclampsia.

• Can occur before, during or after birth. Postpartum eclampsia usually occurs within the first 48 hours, but some cases can develop beyond 48 hours.

Normal Pregnancy BP

• Normally, DBP drops 10mmHg below non-pregnant values around mid-gestation and then slowly climbs up to non-pregnant values in the third trimester. 

What do we need to monitor in individuals taking magnesium for pre-eclampsia?

• Deep Tendon Reflexes

• Additionally, since magnesium is excreted renally, we must assess kidney function and urine output. We want to see diuresis in 24-48 hours as that's a sign of good kidney perfusion since the arteries stopped spasming. However, diuresis without excreting magnesium is a sign of impending renal failure.

• Resp rate

Biceps Reflex

Thumb is placed on the biceps tendon and a downward blow is struck to cause flexion at the elbow

Patellar Reflex

Percussion hammer struck at the patellar tendon to evoke extension of the knee

Ankle Clonus

• Examiner supports the leg with the knee flexed and sharply dorsiflexes the foot. No oscillations should be seen when the foot is dorsiflexed or dropped (negative clonus).

What is the treatment of pre-eclampsia with severe features?

If pre-eclampsia with severe features is diagnosed, birth is warranted regardless of gestational age. Vaginal birth is preferred. If the patient is under 35 weeks gestation, corticosteroids are given to promote fetal lung maturation. 12mg IM betamethasone every 24 hours is the dose, and this is why it is ideal if the birth can be delayed for 48 hours.

Why is Magnesium Sulphate Given to Patients with pre-Eclampsia? What are the doses and routes of admin?

• Magnesium sulphate is given to patients with pre-eclampsia to prevent seizures.

• Usually given IV with a loading dose of 4g infused over 20-30 mins followed by a maintenance dose.

• Rarely given IM because of pain and tissue damage. IF it is given IM, 5mg is given in each glute muscle, and repeated at 4 hour intervals.

Antidote for Magnesium Sulphate Toxicity

 Calcium gluconate is the antidote given by slow IV push.

What marks resolution of preclampsia/eclampsia after birth?

• Symptoms of preeclampsia/eclampsia resolve after birth, though hypertension may persist. Resolution of the disease process is marked by diuresis occurring 24-48 hours after birth.

How long does HELLP resolve in after birth?

• HELLP resolves in 72-96 hours after birth, but in those hours lab values may be wonky.

What is used and what is contraindicated to control bleeding PP after pre-eclampsia

Oxytocin and prostaglandins are used to control bleeding in post partum patients with pre-eclampsia as they cannot tolerate excess blood loss. Ergot products are contraindicated as they increase BP.