• Nathan Riley, MD

Obgyno Wino Podcast Episode 17 - Chronic Hypertension in Pregnancy (Part 2)

Updated: Jul 23, 2019

“Many are the strange chances of the world, and help oft shall come from the hands of the weak when the Wise falter.” - J.R.R. Tolkien, The Silmarillion

2018 Malbec from Öko Winery

PB#203 - Published December 2018

In Part 1, I covered:

- definition of chronic hypertension (cHTN) in pregnancy

- workup/diagnosis

- differential diagnoses

- prenatal checklist

Five Pearls for Part 2

  1. Goal BP range w/ oral treatment throughout pregnancy: 120-159 mmHg/ 80-109 mmHg

  2. Dropping pressures too low/quickly may cause hypoperfusion and big problems for both mom and fetus

  3. Up-titration of BP meds and close follow-up is recommended for patients requiring treatment in pregnancy

  4. Remain vigilant in BP monitoring for up to 2 weeks postpartum. Counsel patients appropriately on signs and symptoms of severe preeclampsia

  5. In absence of superimposed preeclampsia, delivery should not be recommended earlier than 37wga. If BPs can't be controlled, delivery should not be delayed beyond 34wga.

Treatment in pregnancy

- your goal in initiating antihypertensive therapy is to prevent sustained severe range BPs (≥160/110mmHg) with the hope of preventing stroke and other end-organ damage from high pressures, but not dropping them so low as to cause hypoperfusion of organs and baby

- aim for 120-159 mmHg/ 80-109 mmHg

- if the patient has co-morbidities such as diabetes or renal disease, your MFM or cardiology consultants may want to aim even lower, particularly if there is already evidence of end-organ damage or ventricular hypertrophy

- if they were on anti-hypertensive therapy prior to pregnancy, probably best to continue therapy, though this is debated and should be individualized (except for ACE-I and ARB, as mentioned in Part 1 unless the patiently is completely dependent on them)

Selecting an agent - BPs high but not severe

- important to differentiate between acute versus chronic treatment

- Oral therapies are generally used to keep blood pressures within that ideal range mentioned above. Immediate-release Nifedipine is the exception, as it is a great agent for managing acute hypertensive urgency.

- These meds may need to be titrated over 24-48 hrs in the inpatient setting

- You'll usually only be referring to Table 2 if you are trying to keep the patient pregnant or in postpartum patients

- In my practice, methyldopa and HCTZ are last ditch efforts

- HCTZ, in theory, can cause oligohydramnios, but this hasn't panned out through available data

- Labetalol preferred β-blocker; other β-blockers, such as Atenolol, are linked to growth restriction and low birth weight

Selecting an agent - BPs persistently severe

- goal: prevent stroke (particularly if pressures are sustained >180 mmHg systolic or 120 mmHg diastolic (if >240/140 the ICU and your friendly MFM - this is an emergency!)

- before talking protocols, you're not going to administer a medication to rapidly drop a person's BP from the severe range unless you need to

REMEMBER: these patients are accustomed to higher pressures, and so are there placenta/baby and other organs. Don't bottom them out!

- there are formalized treatment algorithms in the practice bulletin, but here's the skinny:

- If a patient is found to have a BP in the severe range (≥ 160 mmHg systolic or ≥ 110 mmHg diastolic), don't panic. Get some medications ready (see below). Re-check BP in 15 minutes. If still in the severe range, pick a starting medication. Evidence hasn't supported one over the other. So your pick...

Labetalol (administered over 2 minutes to avoid dropping pressure too rapidly):

  1. Give 20 mg IV

  2. Re-check BP in 20 minutes (still severe?)

  3. Give 40 mg IV

  4. Re-check BP in 20 minutes (still severe?)

  5. Give 80 mg IV

  6. Re-check BP in 20 minutes (still severe?)

  7. Switch agents - initiate Hydralazine protocol above

Hydralazine (administered over 2 minutes to avoid dropping pressure too rapidly):

  1. Give 5 or 10 mg IV

  2. Re-check BP in 20 minutes (still severe?)

  3. Give 10 mg IV

  4. Re-check BP in 20 minutes (still severe?)

  5. Switch agents - initiate Labetalol protocol below

Nifedipine (immediate release formula; great if no IV access)

  1. Give 10 mg tablet PO

  2. Re-check BP in 20 minutes (still severe?)

  3. Give 20 mg tablet PO

  4. Re-check BP in 20 minutes (still severe?)

  5. Give 20 mg tablet PO

  6. Re-check BP in 20 minutes (still severe?)

  7. Switch agents - initiate Labetalol protocol below

- some other considerations...if you see severe range BPs, you should repeat labs to evaluate for end-organ damage (serum CBC, CMP, and uric acid; +proteinuria assessment)

- IV infusions can be considered for labetalol or hydralazine (long half-life so difficult to titrate)

- hydralazine: 50% of recipients will experience adverse effects, many of which resemble severe preeclampsia (epigastric pain, fluid retention and oliguria through activation of renin-angiotensin system, headache)

- if none of these work, nicardipine or esmolol infusion or IV enalapril may be considered as 2nd line, but consult with anesthesia, MFM, and/or CCU first

- also...if you hadn't guessed, throughout all of this, continuous fetal monitoring is important

- if your patient has severe features of superimposed preeclampsia (hint: giving antihypertensives is probably going to qualify), you should consider magnesium sulfate for seizure prophylaxis

- mag sulfate and regional anesthesia may both effect blood pressures, so keep that in mind so that you don't accidentally cause hypoperfusion

Intrapartum considerations for women w/ cHTN in pregnancy

- strict monitoring of I/O (esp if requiring frequent dosing of antihypertensives)

- continue oral antihypertensive regimen

- careful with IV fluids

- be patient with the first stage of labor to avoid c-section (data suggest that women w/ cHTN w/ superimposed preeclampsia have longer first stages)

- epidural is still safe

- general anesthesia is less safe in these patients; intubation and extubation are associated w/ acute BP elevations

Timing of delivery

- must balance risks of prematurity to newborn against maternal risks of continuing pregnancy as underlying hypertensive disease worsens

- 37w0d - 39w0d for patients w/ cHTN and no other significant maternal or fetal co-morbidities (though waiting until 39w6d can be considered cautiously w/ some patients); when you opt for delivery within that range depends on whether they require oral hypertensives or if they develop new co-morbidities

- no later than 37w0d for patients w/ cHTN and superimposed preeclampsia

- no later than 34w0d for patients w/ cHTN and superimposed severe preeclampsia

** remember to initiate steroids for fetal lungs if delivering at <37 wga, but don't delay delivery for 2nd dose if maternal or fetal condition requires urgent delivery after the first dose

*** important to remember that a "honeymoon period" may occur in severe preeclamptics after administration of corticosteroids as reflected by modestly improved lab values (e.g. transaminemia) but that their administration does not improved outcomes

Postpartum considerations

- auto-transfusion after delivery results in a rapid influx of fluid into the intravascular space and, thus, may cause hypertension to present postpartum, particularly w/in the first two weeks

- upon discharge, patient should be seen in ambulatory clinic 4-7 days after discharge

- they should continue to check BPs at home; counsel them on pertinent signs and symptoms of severe preeclampsia that should prompt evaluation

- laying out expectations is important

- NSAIDs have been demonized due to concern that they may exacerbate hypertension (decreased prostaglandin production, decreased vasodilation, increased sodium retention), but data support their safety overall in cHTN

- if patient requires an oral medication be started prior to discharge:

i. extended release Nifedipine is a great option

ii. β-blocker (propranolol and labetalol preferred as they aren't concentrated in breastmilk)

iii. ACE-I also acceptable at lower doses

iV. Diuretics feasible but may decrease milk production

- f/u with their PCP for chronic management of HTN

121 views0 comments