Preeclampsia

Anesthesia Implications

Anesthesia Implications

Difficult airways – Preeclampsia increases risks of a difficult airway. This is due to upper airway edema as a result of third spacing.

Neuraxial and epidural anesthesia – Neuraxial anesthesia, if not contraindicated, is the anesthetic of choice in a cesarean section to help control blood pressure and improve uteroplacental perfusion. If delivering naturally, be sure to place the epidural early to avoid general anesthesia if the patient’s condition warrants an emergency cesarean section.

Antihypertensives – Medications are rarely given unless the patient is exhibiting severe symptoms. If the patient is showing these symptoms, the objective is to keep BP < 160/110. Medication is given to prevent stroke, MI, or placental abruption. Hypertensive emergencies are typically treated with labetolol nifedipine, or nicardipine. For patients resistant to these medications, sodium nitroprusside, nitroglycerine, and fenoldopam are typically effective. Caution should be exercised when using beta blockers as they run the risk of reducing uterine blood flow and inhibiting labor.

Hypertensive drug responses – Drugs like Ketamine are generally avoided because of potential rises in blood pressure. Exaggerated responses to Methergyn and sympathomimetics may be seen.

Magnesium therapy – if the patient is on this therapy, they will have a heightened sensitivity to nondepolarizing muscle relaxants (NDMRs), and increased risks for both uterine atony and hemorrhage.

Pulmonary edema – third spacing, in general, is a real problem for these patients as there is likely endothelial damage and low oncotic pressure. Be on the watch for signs of pulmonary edema.

Fluid replacement – this can be tricky because of the risks of pulmonary edema and other third spacing issues. Arterial and/or central lines are recommended for use when gauging the patients need for fluids.

Postop – if the patient has HELLP syndrome as a comorbidity, TTP can occur postoperatively.

Pathophysiology

Considered a hypertensive disorder of pregnancy.

Classic triad of symptoms – hypertension (BP > 140/90), proteinuria (>300 mg/24 hours), and generalized edema. This is the classic triad, however, generalized edema is no longer a required symptom to be diagnosed with preeclampsia. Diagnosis may also be made if the patient demonstrates thrombocytopenia ( 1.1 mg/dL), pulmonary edema, or cerebral/visual symptoms. To be diagnosed the parturient should have a normal blood pressure during the first 20 weeks of pregancy. Severe preeclampsia is defined as a BP > 160/110.

Preeclampsia AND gestational hypertension are defined as parturient hypertension sometime after 20 weeks of gestation. What is the difference between preeclampsia and gestational hypertension?
Preeclampsia is accompanied by proteinuria. 80% of patients will develop preeclampsia after 34 weeks of gestation. If developed prior to 34 weeks, there is a much higher risk for adverse outcomes.

Symptoms of preeclampsia AND eclampsia include hypertension, proteinuria, and generalized edema. What then is the difference? Eclampsia includes seizures.

Risk factors – obesity, advanced maternal age, and nulliparity.

Treatment – delivery of the baby and placenta is the treatment. During pregancy, magnesium sulfate is typically administered to prevent seizures. The normal dose is 4-6 grams IV followed by a continuous infusion of 1-2 g/hr. Serum concentrations are maintained between 2.0 – 3.5 mEq/L.

Smoking – this habit is actually protective against preeclampsia

Gestational hypertension will resolve within 12 weeks postpartum. If it does not, the condition would be classified as chronic hypertension.

Additional Notes:

According to the NHBPEP, the diagnosis of preeclampsia should still be considered even in the ABSENCE of proteinuria if the following conditions are present:
1. persistent epigastric or right upper quadrant pain
2. persistent cerebral symptoms
3. fetal growth restriction
4. thrombocytopenia
5. elevated serum liver enzymes.

References

Hines. Stoelting’s anesthesia and co-existing disease. 7th edition. 2018. p. 676 – 678
UptoDate. Retrieved from www.uptodate.com. 2020.