Hypertension in Pregnancy

BP normally decreases initially (nadir at 16-20wks) then increases in pregnancy.  Baseline 5-10% preeclampsia risk in primips.

Most common complication in pregnancy (2-3%)

Definitions

• Hypertension: blood pressure exceeding 140/90 mm Hg
• Hypertension with onset >20 weeks GA – PIH
• Mild pre-eclampsia: PIH, proteinuria, no end organ damage
• Severe pre-eclampsia: PIH, proteinuria, end organ damage
• Eclampsia: pre-eclampsia plus convulsions
• Hypertension with onset < 20 weeks, w/o proteinuria – CHRONIC HTN
• Transient hypertension of pregnancy or chronic hypertension identified in   the latter half of pregnancy – GESTATIONAL HTN
• Preeclampsia superimposed on chronic hypertension
• HELLP: haemolytic anemia, elevated liver enzymes, low platelets

Pathogenesis

Failure of the second wave of trophoblastic invasion of spiral vessels (normally will get rid of surrounding muscle) – leads to tight spiral vessels, decreased prostacyclin (vasodilator), increased thromboxane (vasoconstrictor) – the placenta releases cytokines, free radicals and complement fixation – inflammatory response, endothelial cell damage, fibrin deposition, HTN – vasoconstriction – vascular bed most affected = presentation (kidney – pre-eclampsia; liver – fatty liver; reticuloendothelial – HELLP)
* VASOSPASM

Symptoms:                                                                     Signs:

Headaches                                                            HTN

Visual disturbances                                          Retinal vsaospasm

Epigastric or RUP pain                                    Hepatic tenderness

Edema                                                                    Hyperreflexia/clonus

Treatment

• Delivery!
• Continuous fetal monitoring
• Magnesium sulphate for prevention of seizures (4g IV bolus over 20 minutes, then 2-4g/hr) à continue for 12-24 hr post partum and must monitor for toxicity (↓DTR, ↓RR, anuria, hypotonia, CNS/cardiac depression) à antagonist calcium gluconate (10%), 1g or 10mL IV over 2 minutes
• Antihypertensives
  • Hydralazine 2-10mg IV bolus over 5 minutes, then q15-30minutes prn
  • Labetolol 50-100mg IV q10minutes (contraindicated if poor liver function)
  • Methyldopa 250mg bid – 1g tid
  • Nifedipine 10mg PO q4-8h
• Admission orders
  • NPO
  • Bedrest
  • Vitals and DTR q1h
  • Fetal monitor
  • IV NS
  • Foley
  • I/O q1h
  • Urine dip d12h
  • Labs – Hgb, PLT, Cr, AST/ALT, Uric acid, urine protein
    • Consider peripheral smear, PT/PTT, LDH
  • NST qdaily
  • BPP
  • MgSO4 4g IV push then 2g IV q1h (continue until 24 hr postpartum)
  • Hydralazine 5mg IV push over 5 minutes q15minutes until BP <140/90, repeat 6 hr later if BP >140/90