Anesthesia Considerations 

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