Preeclampsia

 

 

Considerations 

 

  • Pregnancy considerations (difficult intubation, aspiration, ↓ time to desaturation, aortocaval compression, 2 patients)

  • Multisystem disease:

    • Airway: edema → even more difficult 

    • CNS: seizures, intracranial hemorrhage (ICH), cerebral edema,  ICP

    • Respiratory: pulmonary edema (secondary to hypoalbuminemia & hypertension)

    • CVS: relatively hypovolemic,  SVR, hyperdynamic, hypertensive crisis, LV dysfunction

    • Renal dysfunction: oliguria, ATN

    • Coagulopathy: thrombocytopenia, MAHA, risk of DIC

    • HELLP (Hemolysis, Elevated Liver enzymes, Low Platelets)

  • ↓ uteroplacental perfusion, IUGR, placental abruption, premature labour & delivery

  • Medications: antihypertensive/anticonvulsant therapy (including risk of MgSO4 toxicity)

  • Potential delivery & resuscitation of premature infant:

    • Steroids if gestational age < 34+6 

    • MgSO4 for neuroprotection if gestational age < 31+6

  • Consider delivery:

    • If severe preeclampsia at any gestational age

    • If non-severe preeclampsia > 37 wks gestational age

 

 

Goals 

 

  • BP control (sBP <160 mmHg, dBP <110 mmHg) (SOGC 2014

  • Prevent end-organ complications (seizures, ICH, ischemia)

  • Optimize fluid status

  • Optimize uteroplacental perfusion

  • Excellent labour analgesia to mitigate adverse effects of pain

  • Prevent complications if general anesthesia:

    • Failed airway 

    • Hypertensive crisis

 

 

Anesthetic Options 

 

  • Anesthetic technique depends on:

    • Fetal distress

    • Airway assessment

    • Platelets/coagulation profile

  • Choices:

    • Epidural:

      • Preferred technique

      • Allows for titration of local anesthetic & IV fluids (minimizes risk of BP fluctuations & pulmonary edema)

      • If using for cesarean, consider not adding epinephrine (may decrease uteroplacental perfusion)

    • Spinal:

      • Traditionally relatively contraindicated in severe preeclampsia for fear of marked hypotension, but recent studies (as per Chestnut) suggest spinal may be appropriate

    • GA:

      • Least desirable

      • Risk of ICH from hypertension secondary to intubation &  possibility of difficult intubation secondary to airway edema

  • Chestnut suggests the following for platelets:

    • < 50: neuraxial technique contraindicated

    • 50-80: risk vs benefit (consider trend, function, other coagulation investigations)

    • > 80: likely safe

    • SOGC 2014 guidelines suggest > 75 is safe unless coagulopathy, falling platelet count or other antiplatelet agents

 

 

Management of Eclamptic Seizure 

 

  • SOGC 2014 guidelines:

    • Primary immediate goals:

      • Stop convulsions with MgSO4 (4g bolus over 20min, then 1g/hr) 

      • Establish a patent airway 

      • Prevent major complications (e.g., hypoxemia, aspiration)

      • Phenytoin & benzodiazepines should NOT be used for eclampsia prophylaxis or treatment, unless there is a contraindication to MgSO4 or it is ineffective

  • Further obstetric management:

    • Antihypertensive therapy (labetolol 10-20mg IV or hydralazine 5-10mg IV) 

    • Induction or augmentation of labor 

    • Expeditious (preferably vaginal) delivery

    • Fetal bradycardia typically occurs during &/or immediately after a seizure but does not mandate immediate delivery unless it is persistent

  • Considerations of magnesium therapy:

    • Interaction with NdMRs (nondepolarizing muscle relaxants):

      • Increases the potency & duration of NdMRs (titrate/reduce dose)

      • Directly inhibits acetylcholine release & postmembrane sensitivity to acetylcholine

      • No change in succinylcholine (onset & duration unchanged, use standard dose)

    • Effects on uterine tone:

      • Potential PPH as a tocolytic agent; however, studies demonstrate no increase in blood loss

      • Have uterotonics available, group & screen completed

    • Interaction with calcium channel blockers (specifically nifedipine)

    • Possibly greater hypotensive effects