Preeclampsia is a pregnancy-specific, multi-organ system disease characterized by hypertension and proteinuria beginning after 20 weeks gestation and resolving by 6–12 weeks postpartum.
May be mild, severe, or part of a larger spectrum of diseases, including pregnancy-induced hypertension, eclampsia, and hemolysis, elevated liver enzymes, and low platelet count (HELLP) syndrome.
Epidemiology
Incidence
5–8% of all pregnancies; rising incidence in the US.
Increased incidence of Cesarean section in severe cases.
Early onset preeclampsia (before 34 weeks gestation) associated with increased risk for future cardiovascular disease.
Mortality
Comprises ~10–15% of maternal death worldwide.
Third leading cause of maternal mortality in the US (behind pulmonary embolus and hemorrhage).
Late onset preeclampsia (after 34 weeks gestation) has lower maternal and fetal morbidity and mortality compared to early disease.
Etiology/Risk Factors
Maternal factors:
Nulliparity
Preeclampsia in previous pregnancy
Family history of preeclampsia
Pre-gestational diagnosis of chronic hypertension, diabetes, vascular, or renal disease
Obesity (BMI >35)
Presence of antiphospholipid antibodies
African American or Filipino race
Age >40 years
Paternal factors: Male who previously fathered a preeclamptic pregnancy; male born from a preeclamptic pregnancy.
Physiology/Pathophysiology
Two proposed hypotheses:
An atypical maternal immune response to embryonic trophoblasts results in impaired invasion of trophoblastic cells into the uterine wall. This leads to maladaptation of myometrial spiral arteries with reduced, high-resistance, utero-placental flow. The irregular placental perfusion can cause placental hypoxia and the release of inflammatory cytokines into the maternal circulation with consequent endothelial dysfunction.
An imbalance of placental production of prostacyclin and thromboxane can result in systemic vasoconstriction and placental ischemia.
Anesthetic GOALS/GUIDING Principles
Assess the severity of disease and end-organ damage.
Avoid hemodynamic extremes, especially when general anesthesia is attempted (intubation and extubation).
Gentle fluid resuscitation with caution of excess fluid administration.
Delivery of fetus/placenta is the only cure.
Diagnosis⬆⬇
Symptoms
Seizures, visual disturbances, headaches
Pulmonary and peripheral edema
Shortness of breath
Abdominal pain
Nausea/vomiting
Vaginal bleeding
Decreased urine output
History
Prenatal history and care, including pre-gestational diagnoses of hypertension and renal disease.
Prevention: Aspirin may be prescribed for high-risk patients (abnormal uterine artery Doppler at 16 weeks gestation). It is not recommended for prophylactic use in low-risk patients.
Antihypertensives
Hydralazine (first line): 5–10 mg IV q15 minutes
Labetalol (first line): 20 mg IV q10 minutes up to a maximum dose of 300 mg.
Nifedipine (second line): 10 mg PO TID titrated to effect for maximum dose of 120 mg daily. Should be avoided in women with CAD, DM >15 years, or >45 years old.
Continuous epidural infusion can block sympathetic nerve fibers and may assist with BP control.
Magnesium sulfate (first line): 4–6 g IV bolus over 15 minutes, followed by 1–2 g/hr for seizure, prophylaxis. Therapeutic level ~6–8 mEq/mL
Ergot alkaloids (e.g., Methergine) should be avoided as it may cause a hypertensive crisis.
Diagnostic Tests & Interpretation
Labs/Studies
24-hour urine protein
Urine protein: urine creatinine ratio
Hgb/Hct/platelet count
Liver enzymes to assess for HELLP syndrome
Blood type and screen or cross-matching, as appropriate
Fetal ultrasound
Echocardiogram if suspicion for cardiomyopathy
CONCOMITANT ORGAN DYSFUNCTION
CNS: Visual disturbance, headache, eclamptic seizures, or cortical blindness may be due to cerebral edema.
CV: Vasoconstriction due to endothelial dysfunction and consequent hypertension.
Respiratory: Increased risk of pulmonary edema due to lower colloid oncotic pressures and increased capillary permeability
Renal: Proteinuria due to increased permeability of albumin and other plasma proteins.
GI: Hepatic edema causing RUQ pain; rupture of Glisson's capsule in severe disease may lead to hepatic hemorrhage; elevated liver enzymes in HELLP syndrome.
Circumstances to delay/Conditions
Appropriate BP control is necessary before induction of general anesthesia, even in emergent cases.
Coagulopathy may preclude the use of neuraxial anesthesia.
Classifications
Mild preeclampsia: Systolic >140 mm Hg or diastolic >90 mm Hg with proteinuria (>300 mg/24 hrs)
Severe preeclampsia: Systolic >160 mm Hg or diastolic >110 mm Hg and/or end-organ damage.
Renal involvement defined as proteinuria >3 g/24 hrs, 3+ on urine dipstick, or sudden oliguria
CNS involvement
Pulmonary edema
Liver dysfunction
RUQ/epigastric pain
Thrombocytopenia
HELLP syndrome
Evidence of fetal compromise
Eclampsia: New onset of grand mal seizures occurring during or after pregnancy that do not have another identifiable cause.
Treatment⬆⬇
PREOPERATIVE PREPARATION
Premedications
Avoid benzodiazepines and limit narcotics.
Nonparticulate antacid (i.e., bicitrate)
MgSO4 infusion for seizure prophylaxis
Special Concerns for Informed Consent
Regional anesthesia and coagulopathy
Possible need for blood transfusion
Possible need for invasive monitoring
INTRAOPERATIVE CARE
Choice of Anesthesia
ACOG and ASA recommend regional anesthesia in patients without evidence of coagulopathy.
Early placement of epidural should be considered to avoid general anesthesia.
Spinal anesthesia is a suitable alternative to epidural for Cesarean section even in severe preeclampsia.
Monitors
Standard ASA monitors
Consider arterial line for better hemodynamic monitoring.
CVP and PAP monitoring is rarely necessary.
Induction/Airway Management
Neuraxial techniques: Consider supplemental O2 via facemask or nasal canula for patients with neuraxial anesthesia/analgesia.
General endotracheal anesthesia (GETA)
Rapid sequence induction, along with aspiration precautions.
Difficult airway: There is an increased risk of failed intubation due to pharyngolaryngeal edema. Be prepared for a difficult airway, including having a supraglottic device available.
Careful attention to BP management with induction and intubation; intracranial hemorrhage, secondary to severe hypertension, is the leading cause of morbidity and mortality in preeclamptic women. Consider having esmolol and nitroglycerin available.
Hypotension with induction may lead to fetal compromise/distress.
Maintenance
Neuraxial. In the OR, intermittent boluses with high concentration local anesthetics (possibly without epinephrine) for surgical anesthesia/analgesia.
GETA. Less than 0.5 MAC of volatile anesthetic supplemented by nitrous oxide after delivery of the fetus. All inhalational agents cause uterine relaxation and can contribute to postpartum hemorrhage.
MgSO4 causes prolonged duration of non-depolarizing neuromuscular blockade.
Gentle fluid resuscitation with caution to avoid fluid overload
Extubation/Emergence
The patient is considered to have a full stomach.
Avoid severe hypertension.
Follow-Up⬆⬇
Bed Acuity
ICU admission may be indicated if there is evidence of severe end-organ damage, including renal failure, cerebral hemorrhage, hepatic rupture, and/or pulmonary edema.
Routine postpartum ward may be appropriate in a patients without pulmonary edema or hemodynamic derangements.
Preeclampsia and all of its associated complications may present de novo after delivery.
TurnerJA.Diagnosis and management of pre-eclampsia: An update. Int J Womens Health. 2010;2:327–337.
SteegersEA, von DadelszenP, DuvekotJJ, et al.Lancet. 2010;376(9741):631–644.
GogartenW.Preeclampsia and anaesthesia. Curr Opin Anaesthesiol. 2009;22:347–351.
American Society of Anesthesiologists Task force on Obstetric Anesthesia. Practice Guidelines for Obstetric Anesthesia. Anesthesiology. 2007;106:843–863.
VisalyaputraS, RodanantO, SomboonviboonvvW, et al.Spinal versus epidural anesthesia for cesarean delivery in severe preeclampsia: A prospective randomized, multicenter study. Anesth Analg. 2005;101:862–868.
Additional Reading⬆⬇
American College of Obstetricians and Gynecologists (ACOG)Practice Bulletin: Diagnosis and management of preeclampsia and eclampsia. Obstet Gynecol. 2002;99 (1):159–167.
LewisG, ed. 2007. The confidential enquiry into maternal and child health (CEMACH). Saving mothers’ lives: Reviewing maternal deaths to make motherhood safer-2003–2005. The Seventh Report on Confidential Enquiries into Maternal Deaths in the United Kingdom. London: CEMACH.
Preeclampsia is a relatively common, transient multi-organ system disease diagnosed after 20 weeks gestation.
Early placement of a epidural should be considered to assist with BP control and as a preferred alternative to general anesthesia. Rule out coagulopathy and thrombocytopenia before neuraxial anesthesia is attempted.
When a GETA is indicated, be prepared for a difficult tracheal intubation and have back-up airway equipment, including supraglottic devices, if available.