A middle aged female G1P0 @ 30 weeks presents to your emergency department with new lower extremity swelling and a severe headache. Her initial blood pressure reveals a BP of 170/112. The patient appears anxious since this is her first pregnancy and she is otherwise a healthy individual.
You obviously are concerned about preeclampsia in this patient. So what are the criteria for diagnosis?
For our purposes in the emergency department we are going to have two thresholds which will determine if this pregnant patient needs aggressive blood pressure control and magnesium loading now or can wait to see their OB:
- Mild Preeclampsia (Do not need aggressive BP control in the ED)
- BP > 140/90
- 2+ on urine dipstick
- Well appearing, mild leg swelling, otherwise asymptomatic
- Severe Preeclampsia (Need aggressive BP control in the ED)
- BP > 160/110
- 2+ on urine dipstick
- Any concerning sign/symptom or abnormal lab value will bump your patient up to severe: Liver enzyme elevation, thrombocytopenia (plt < 100,000/mm3), elevated creatinine (>1.2 mg/dL), persistent headache, neurological findings or visual disturbance, pulmonary edema, RUQ pain or oliguria
SYSTEMIC EFFECTS OF PREECLAMPSIA
So your patient has severe preeclampsia and you want to begin treating her blood pressure and getting in touch with the OB/Gyn on call but before you do that you should examine the patient and think about the possible complications that should be on your mind.
Here is a quick bit on what complications you can expect and what you should be on the look out for:
- Cardiovascular: Preeclamptic patients have increased afterload from new hypertension, decreased preload (as volume expansion normal to pregnancy is reduced in these patients) and endothelial damage, all of which can result in higher risk of pulmonary edema.
- Perform a thorough cardiac and lung exam
- Consider a CXR and EKG to evaluate
Neurologic: The two most feared complications of severe preeclampsia are an aggressive tonic-clonic type seizure and stroke. Another less common entity to be on the lookout for is posterior reversible encephalopathy syndrome (PRES). Normally cerebral auto-regulation maintains constant cerebral blood flow in the face of hypertension by vasoconstriction however this fails above a certain blood pressure level which is thought to be lower in preeclamptic patients. Increased CBF produces hyperperfusion, disruption of the blood-brain barrier, and edema formation. PRES patients will typically present with headaches, nausea, altered mental function, visual disturbances, and seizure.
- Perform a thorough neurological exam
- In woman presenting with any lateralizing finding on neuro exam, consider emergent CT brain.
- MRI is necessary for the diagnosis of PRES
- Renal: Preeclamptic patients experience decreased volume expansion, decreased renal blood flow, renal artery vasospasm and breakdown of the glomerular apparatus. This results in significant oliguria as well as leakage of protein into the urine. Urine output may benefit from fluid resuscitation however pulmonary edema is a real risk so this should be avoided or approached cautiously.
- Ask about urine output, check creatinine and evaluate for proteinuria
- Uterine: Compromised uterine blood flow results secondary to incomplete remodeling of the spiral arteries in the placenta. This leads to abnormal fetal growth, oligohydramnios, increased risk of abruption and sudden fetal decompensation.
- Perform bedside ultrasound to assess for fetal heart tones
- If vaginal bleeding, think abruption until proven otherwise
- The patient will need continuous electronic fetal monitoring as well as further assessment of fetal growth, and amniotic fluid assessment
LABS & WHY
You get out of the patient room and now you need to decide what labs order:
- CBC/Chem: Standard. Also will help you look for anemia and thrombocytopenia which can be seen in HELLP (hemolysis, elevated liver enzymes and low platelets). HELLP is an independent factor for poor prognosis in preeclampsia.
- LFTs: Again, evaluate for HELLP and also screen for cholestasis of pregnancy if patient with RUQ pain.
- Coags: Screen for DIC if patient appears sick. Coagulation screen does not add any value in light of normal platelet count.
- Uric Acid: Elevated levels of uric acid have been shown to be specific for preeclampsia though literature shows that decisions just as early delivery should not be based off this lab value alone.
- Urinalysis/Urine dip: Evaluate for proteinuria.
NOW ON TO BLOOD PRESSURE CONTROL
While labetalol and methyldopa are first line treatments for management of hypertension in pregnancy in the outpatient setting, the evidence for acute therapies are mixed. A recent cochrane review comparing hydralazine, labetalol and oral nifedipine concluded that until better evidence is available, the choice of antihypertensive should depend on the clinician's experience and familiarity with the particular drug.
Here are treatment recommendations and when you should decide to move on to the next agent:
- Hydralazine 5 mg, or 10 mg IV or IM. A dose of 5-10 mg can be repeated at 20-minute intervals as needed. If there is no response after 20 mg IV or 30 mg IM then another agent can be considered.
- Labetalol 20 mg IV as a bolus can be given initially. Further 40 mg 10 minutes later if needed followed by two further doses at 80 mg 10 minutes apart, to a maximum dose of 220 mg. If adequate response is not achieved, an alternative agent can be used.
- Short-acting nifedipine can be given orally at 10 mg to start, repeated at 30 minute intervals if required for up to 3 doses. If adequate response is not achieved, an alternative agent can be used.
- In rare cases where the woman is not responding to any of these three drugs or there is evidence of hypertensive encephalopathy, sodium nitroprusside can be considered, starting at 0.25 μg/kg/minute, to a maximum dose of 5 μg/kg/minute. If used for longer than 4 hours , fetal cyanide poisoning is a concern.
All patient's with severe preeclampsia need seizure prophylaxis with magnesium, it improves mortality!
- Loading dose : 4g over 5-10 minutes
- Maintenance: 1-2mg/hr for 24 hours
Call an OB! These patients need admission for observation, blood pressure control, magnesium maintenance and continuous fetal monitoring. Get OB on board as soon as you can!
Our patient's labs ended up revealed no signs of HELLP, normal uric acid, normal creatinine and 2+ protein in her urine. She receiving 20 mg IV hydralazine and 40 mg IV labetalol with improvement of her BP to the 140s/90s. She was loaded with magnesium and admitted to the OB service for further management. Another job well done.
- Berzan et al. Treatment of preeclampsia: current approach and future perspectives.Curr Hypertens Rep. 2014 Sep;16(9):473.
- Savaj et al. An Overview of Recent Advances in Pathogenesis and Diagnosis of Preeclampsia. Iranian Journal of Kidney Diseases. Oct2012, Vol. 6 Issue 5, p334-338.
- Alexander et al. Hypertensive Emergencies of Pregnancy. Obstetrics and Gynecology Clinics. Volume 40, Issue 1 (March 2013)
Moattia et al. A review of stroke and pregnancy: incidence, management and prevention. European Journal of Obstetrics & Gynecology and Reproductive Biology. Volume 181, October 2014, Pages 20–27
Firoz et al. Oral antihypertensive therapy for severe hypertension in pregnancy and postpartum: a systematic review. BJOG. Volume 121, Issue 10, pages 1210–1220, September 2014.