Vancouver IM LMR

Thanks Dr. Tran for teaching on this very important topic! Here are the slides from the presentation

SOGC 2022 guidelines

Why does it matter?

• Affects 5-10% of pregnancies
• Leading cause of maternal and neonatal morbidity and mortality worldwide.
• Women with HDP are 2-4x higher risk of developing risk factors and future cardiovascular disease.

Diagnosis of HTN in pregnancy

• HTN should not be diagnosed on a single office BP reading unless BP >160/110 (white coat hypertension affecting 30% of pregnancies!).
  • If blood pressure high in office (>= 140/90 mmHg), confirm Dx of hypertension with out of office BP monitoring (24h ABPM or home BP monitoring – threshold of >25% of readings >135/85 mmHg).

Hypertensive Disorders of Pregnancy

• Gestational HTN: Develops for the first time at >20 weeks without evidence of pre-eclampsia
• Chronic HTN: Develops either before pregnancy or < 20 weeks

Gestational HTN

• Initiate meds once BP > 140/90 to target a diastolic BP of < 85.
• Med choices safe in pregnacy and breastfeeding: Labetalol nifedipine XL, methyldopa
• Why DBP < 85?
  • CHIPS trial (NEJM 2015) looked at patients with chronic/gestational HTN randomized to tight control (DBP < 85) vs less tight (DBP < 100), with the outcome of pregnancy loss or high level neonatal care > 48 hours in 1st 28 days of life. BP achieved was 133/85 (tight) vs 139/90 (less tight).
    • Negative trial – no difference in primary, maternal or neonatal outcomes, but frequency of severe HTN >=160/110 higher in less tight control group.
• CHAP trial (NEJM 2022) showed us that in chronic HTN, treatment of HTN to target < 140/90 vs only treating severe HTN decreased pre-eclampsia (NNT = 15), with no effect on neonatal outcomes from driving the BP down.
  • Exception: Practically for a very small baby, on a case by case basis HTN target may be liberalized to prioritize perfusion to the fetus.

Pre-eclampsia

• Gestational or chronic HTN with new onset proteinuria (urine PCR > 30) or one/more adverse conditions
  • Adverse conditions (bold = deliver regardless of GA)
    • CNS: Headache, visual symptoms, eclampsia, PRES, cortical blindness/retinal deatchment, GCS < 13, stroke/TIA
    • Cardioresp: Chest pain, dyspnea, O2 < 97%, uncontrolled severe HTN despite 3 HTN meds, O2 < 90%/need >50% O2 for over an hour, pulmonary edema, myocardial infarction
    • Heme: Low PLT, PLT < 50, required any transfusions
    • Renal: Elevated creatinine, Cr > 150 with no prior renal disease, new dialysis indication
    • Hepatic: RUQ or epigastric pain, elevated serum AST/ALT, INR > 2 (without DIC or warfarin), hepatic hematoma or rupture
    • Uteroplacental: Atypical or abonrmal non-stress test, fetal growth restriction, oligohydramnios, absent/reversed end-diastolic flow on umbilical artery Doppler, placental abruption, intrauterine death
• Pathophysiology: Impaired placentation -> utero-placental perfusion mismatch -> placental hypoxia -> endothelial dysfunction -> systemic badness
• Features to ask about: Headaches, vision issues, swelling (hands, face), weight gain (more than 5 pounds in a week), abdominal pain (epigastric, RUQ), difficulty breathing
• Labs to send: CBC, lytes, Cr, INR, bilirubin, AST, ALT, ADH, (uric acid – no longer recommended by SOGC), urine PCR
• Prevention
  • Aspirin (81 vs 162 mg) once daily: NNT 61 for prevention of pre-eclampsia. No consensus re: specific dose, question of small increased bleeding with the higher ASA dose
    • Definitely indicated in presence of high risk features: prior preeclampsia, pre-pregnancy BMI > 30, chronic HTN, pre-gestational DM, CKD, SLE/APLA, assisted reproductive therapy
    • Also considered if 2+ of: prior placental abruption, stillbirth, fetal growth restriction, maternal age over 40, nulliparity, multifetal pregnancy
    • ***OBIM at BCWH stops ASA at 36 weeks given viability of the baby in the event of pre-eclampsia + avoiding bleeding risk and issues with epidural on antiplatelets
  • If low dietary calcium intake (<900 mg/day) – supplement 500 mg calcium daily.
  • Exercise (140 mins moderate intensity exercise) for effect size of 25% reduction of developing gestational HTN or preeclampsia
  • Baseline labs (CBC, chem 7, liver enzymes, urine PCR)
  • Consideration of referral to placental assessment program at BCWH (EMMA)
• Treatment of pre-eclampsia
  • HTN management
    • For patients on antiHTN medications, give medication from the other classes
      • What you’ll frequently see -> IV labetalol, immediate-release nifedipine.
      • Remember to give long acting meds as well!!!
    • For severe HTN > 160/110, goal to reduce < 160/110 in the short term and ideally < 140/90.
  • Magnesium sulfate
    • Given for women with severe HTN or adverse maternal conditions for prevention of eclamptic seizures
    • Loading dose of 4 g, then infusion of 1 g/hour. Continues until 24 hours after birth. Requires close monitoring (ICU level)
  • Delivery of the pregnancy (induction of labour if pregnancy viable, or termination of pregnancy otherwise) – multidisciplinary determination (MFM, ObGyn, OBIM)
• Post-partum amangement of preeclampsia: Note that BP rises 3-7 days postpartum often to a higher level than before delivery!!! This is why we need close follow up a few days after discharge to check BP. Majority will have resolution of HTN and lab abnormalities by 6 weeks to 3 months post-partum.
  • Assess cardiovascular risk factors following pregnancy complicated by hypertensive disorder
    • Canadian Postpregnancy Clinical Network recommendation: 6 months post-partum then every 1-3 years – BP, HbA1C, lipids, uACR, Cr
  • Advise patient of future risk of recurrence of a hypertensive disorder in subsequent pregnancies (~20% future risk) + plan to give ASA and counsel exercise for next pregnancy.
  • Persistent HTN or proteinuria after 6-12 months should prompt consideration of a secondary HTN workup!! Captopril and enalapril are safe options in breastfeeding.