Terminology and Classification:
The current classification system by ACOG includes four distinct disorders:
I. Gestational Hypertension: New-onset
hypertension after 20 weeks without proteinuria or other signs of end-organ
damage. It typically resolves by 12 weeks postpartum.
II. Preeclampsia/Superimposed Preeclampsia:
The new onset of hypertension after 20 weeks of gestation, accompanied by one
or more of the following:
a.
Proteinuria
b.
Thrombocytopenia (platelet count <
100,000/μL)
c.
Impaired liver function (elevated
transaminases to twice the normal concentration)
d.
Renal insufficiency (serum creatinine
> 1.1 mg/dL or a doubling of baseline)
e.
Pulmonary edema
f.
New onset cerebral or visual
disturbances.
III.
Eclampsia: The onset of grand mal
seizures in a patient with preeclampsia that cannot be attributed to other
causes.
IV.
Chronic Hypertension: Hypertension
present before pregnancy or diagnosed before 20 weeks' gestation.
Pathogenesis:
I. Pathophysiology: The primary
pathophysiologic basis is now understood to be placental and endothelial
dysfunction, leading to:
a.
Generalized Vasospasm (causing
hypertension and reduced organ perfusion).
b.
Increased Capillary Permeability (causing
edema, including pulmonary edema).
c.
Activation of the Coagulation System
(causing thrombocytopenia).
II. Diagnosis: RollOver Test: This test is
obsolete and no longer used in clinical practice. It has been replaced by more
reliable clinical monitoring and biomarker research.
Assessment and Diagnostic Criteria
The "mild" vs. "severe" classification
of preeclampsia is outdated. The current standard is Preeclampsia vs.
Preeclampsia with Severe Features.
Preeclampsia with Severe Features is diagnosed by the
presence of any of the following:
i.
Systolic BP ≥ 160 mm Hg or Diastolic BP ≥
110 mm Hg on two occasions at least 4 hours apart (antihypertensive therapy is
often initiated sooner).
ii.
Thrombocytopenia (Platelets <
100,000/μL).
iii.
Impaired Liver Function (Elevated AST/ALT
to twice the normal concentration).
iv.
Severe Persistent Right Upper Quadrant or
Epigastric Pain (This indicates liver involvement, not merely an
"aura").
v.
Renal Insufficiency (Serum Creatinine
> 1.1 mg/dL or a doubling from baseline).
vi.
Pulmonary Edema.
vii.
New Onset Cerebral or Visual Disturbances
(e.g., severe headache, scotomata, blurred vision).
Signs/Symptoms:
I. Proteinuria: Diagnostic threshold is ≥
0.3 grams in a 24hour urine collection (gold standard),
II. Oliguria: Defined as < 30 mL/hour over
24 hours,
III. Weight Gain/Edema: These are not reliable
diagnostic criteria as they are common in normal pregnancy.
IV. Diagnosis is based on BP and evidence of
organ dysfunction.
V. HELLP Syndrome: A severe variant of
preeclampsia characterized by Hemolysis, Elevated Liver enzymes, and Low
Platelets.
Management
A. General and Supportive Care:
I. Bed Rest: Strict bed rest is no longer
recommended due to the increased risk of thromboembolism and lack of proven
benefit. Activity may be modified, but mobility is encouraged.
II. Diet: Salt restriction and specific high-protein
diets are not recommended. A balanced, nutritious diet is advised. Salt
restriction can be detrimental.
III. Environment: A calm environment is
supportive, but the primary seizure prophylaxis is pharmacological, not
environmental.
B. Medication Management (Magnesium Sulfate): Indication:
First-line for seizure prophylaxis in preeclampsia with severe features and for treatment of
eclampsia.
I.
Dosing (Updated):
a.
Loading Dose: 4-6 grams IV over 15-20
minutes.
b.
Maintenance Dose: 1-2 grams/hour via
continuous IV infusion pump.
II.
Monitoring for Toxicity (Updated):
a.
Respiratory Rate: Must be > 16/minute.
b.
Urine Output: Must be > 30 mL/hour.
c.
Deep Tendon Reflexes: Must be present
(absence is the first sign of toxicity).
d.
Serum Magnesium Levels: Therapeutic range
is 48 mg/dL.
III.
Antidote: Calcium Gluconate 1 gram (10%
solution) IV over 10 minutes must be available at the bedside.
C. Blood Pressure Management: Antihypertensive medications (e.g.,
Labetalol, Nifedipine) are used to manage severe hypertension (≥ 160/110 mm Hg)
to prevent maternal stroke.
D. Delivery:
Delivery is the
only definitive cure for preeclampsia. The timing is based on gestational age
and disease severity. Vaginal delivery is preferred, but cesarean section is
performed for standard obstetric indications.
Nursing Problem Priorities:
I. Seizure Prophylaxis & Neurologic
Monitoring: Administer MgSO₄ and monitor for signs of toxicity and CNS
irritability.
II. Severe Hypertension Management:
Administer antihypertensive medications as ordered to prevent cerebral vascular
accident (stroke).
III. Maternal-Fetal Surveillance: Continuous
fetal monitoring; frequent maternal vital signs, strict I&O, and assessment
for symptoms of severe features (headache, epigastric pain, visual changes).
IV. Fluid Balance Management: Monitor for
pulmonary edema; avoid fluid overload.
V. Prevention of Complications: Monitor for
progression to HELLP syndrome, eclampsia, placental abruption, and pulmonary
edema.
VI. Patient & Family Education: Educate
on signs/symptoms of worsening condition, emphasizing that the risk persists up
to 46 weeks postpartum.
Dosing Details: First-Line Antihypertensive
Medications in Pregnancy:
The following table provides specific dosing for both
acute/severe hypertension and ongoing maintenance therapy.
|
Medication
|
Route
|
Indication
|
Dosing Protocol
|
Key Monitoring & Nursing Considerations
|
|
Labetalol
|
IV
|
Acute Severe Hypertension
|
• Initial Dose: 20 mg IV push over 2 minutes.
• Repeat Dosing: If target BP not reached in 10 minutes, give 40 mg IV. Then
80 mg IV every 10 minutes as needed.
• Maximum Cumulative Dose: 300 mg per course.
• Continuous Infusion (Alternative): 1-2 mg/min, titrate to effect (max 300
mg).
|
• Contraindicated in patients with asthma, heart
failure, or bradycardia.
• Monitor maternal heart rate (can cause bradycardia).
• Monitor for neonatal hypoglycemia after birth.
|
|
Nifedipine
|
Oral (Capsule)
|
Acute Severe Hypertension
|
• Dose: 10 mg orally.
• Repeat Dosing: May repeat in 20-30 minutes if needed.
• Maximum Dose: 30 mg in 1 hour.
• Formulation Note: Use immediate-release capsule. The capsule can be
pierced and swallowed if the patient cannot swallow it whole.
|
• Avoid sublingual administration due to risk of
precipitous BP drop.
• Common side effects: headache, flushing, tachycardia.
• Synergistic effect with magnesium sulfate; monitor for potential
hypotension.
|
|
Hydralazine
|
IV
|
Acute Severe Hypertension
|
• Initial Dose: 5 mg IV push over 2 minutes.
• Repeat Dosing: If no effect in 20 minutes, give 5-10 mg IV.
• Subsequent doses of 10 mg can be given every 20-40 minutes as needed.
• Maximum Dose: 20-30 mg total.
|
• Onset of action can be slower (10-20 minutes).
• Can cause reflex tachycardia and headaches.
• Associated with more fetal heart rate decelerations than other agents.
|
|
Labetalol
|
Oral
|
Maintenance Therapy
|
• Starting Dose: 100 mg twice daily.
• Titration: Increase every 2-3 days as needed.
• Usual Dosage Range: 200-800 mg twice daily (max 2400 mg/day).
|
• Monitor heart rate and BP.
• Advise patient to avoid sudden position changes (orthostatic hypotension).
|
|
Nifedipine
|
Oral (ER)
|
Maintenance Therapy
|
• Starting Dose: 30 mg once daily (extended-release
formulation).
• Titration: Can increase to 60 mg or 90 mg once daily.
• Maximum Dose: 120 mg daily.
|
• Use extended-release (ER/XL) for maintenance.
• Monitor for peripheral edema and gingival hyperplasia with long-term use.
|
|
Methyldopa
|
Oral
|
Maintenance Therapy
|
• Starting Dose: 250 mg two or three times daily.
• Titration: Increase every 2 days as needed.
• Usual Dosage Range: 500 mg to 2000 mg daily in 2-4 divided doses (max 3000
mg/day).
|
• Safest for long-term use in pregnancy (extensive
safety data).
• Side effects: drowsiness, dry mouth, depression (monitor mood).
• Can cause a positive Coombs' test, rarely hemolytic anemia.
|
Clinical Protocol for Acute Severe Hypertension
(≥160/110 mm Hg)
This is often managed using a standardized algorithm or
"severe hypertension pathway" to ensure timely treatment.
- Confirm
Reading: Re-check BP after 15 minutes with an appropriate-sized cuff.
- Administer
First-Line Agent: Choose one (e.g., Labetalol 20 mg IV).
- Re-assess
BP: Check BP every 10-20 minutes.
- Escalate
if Needed:
- If
BP remains ≥160/110 mm Hg after 10-20 minutes, administer the next dose
in the sequence (e.g., Labetalol 40 mg IV).
- Switch
Agents if Goal Not Met: If the maximum dose of the first agent is
ineffective (e.g., BP still severe after Labetalol 80 mg), switch to a
second-line agent (e.g., Nifedipine 10 mg orally).
- Target:
The goal is to achieve a BP below 160/110 mm Hg within 30-60 minutes and
then maintain it in a safer range (e.g., 140-150/90-100 mm Hg).
- Notify
Physician: If the BP does not respond to two first-line agents, this is
considered refractory hypertension and requires immediate physician
consultation, as it may signal impending crisis.
Important Note: These protocols are for educational
purposes. All medication administration must follow specific, written physician
orders and the official protocols of the treating institution.
