Amniotic Fluid Embolism

Amniotic fluid embolism (AFE) is a life threatening condition in which there is a severe reaction to the amniotic fluid and fetal debris that enter maternal circulation during the birthing process, resulting in cardiovascular collapse. 

The pathophysiology of AFE is not fully understood, and used to be believed to be due to amniotic contents blocking pulmonary circulation. However, current researchers have hypothesized that it is actually due to the activation of the immune response which leads to a “cytokine storm” and the release of pro-coagulation and vasoactive substances, much like you see in systemic inflammatory response syndrome. 

Learn about AFE on the go in episode 252 of the Straight A Nursing podcast. Listen from any podcast platform, or straight from the website here.

The physiological response to this reaction involves:

• Increased pulmonary pressures
• Increased pressure in right ventricle, leading to right ventricular failure
• Left ventricular failure 
• Ventilation/perfusion mismatch
• Pulmonary edema
• Respiratory failure
• Activation of the coagulation cascade, resulting in DIC and ultimately hemorrhage
• Hemodynamic instability
• End organ ischemia
• Multi-organ failure

Who is most at risk for AFE and what’s the prognosis?

According to the AFE foundation, risk factors for AFE are difficult to determine. Studies show that potential risk factors are advanced maternal age, cesarean delivery, multiples, preeclampsia, eclampsia, placental abnormalities, polyhydramnios, labor induction, meconium stained amniotic fluid, and vaginal delivery using forceps or a vacuum device.

Prior reports showed a mortality rate of 99 percent, but newer reports (and more defined parameters for what constitutes AFE) indicate a mortality rate of approximately 20 percent. However, it is important to note that most individuals who do survive do not have good outcomes due to neurological impairment secondary to prolonged hypoxia. Further, when AFE occurs prior to delivery, mortality rates for the neonate are 20 to 60 percent and neurological impairment exists in approximately half of those who survive.

Now that you have a basic understanding of what AFE is, let’s go through how to care for these patients using the Straight A Nursing LATTE method.

L: How does the patient LOOK?  

Clinical manifestations of AFE have an abrupt onset either during delivery or within thirty minutes of delivery. Signs and symptoms include:

• Sudden development of hypoxemic respiratory failure, severe hypotension and cardiac arrest occurs in the majority of patients
• Low O2 saturation with dyspnea and tachypnea
• Coarse or “wet” lung sounds due to pulmonary edema
• Cyanosis
• Hemorrhage due to clotting factors being depleted with DIC
• Feeling of impending doom
• Tonic-clonic seizures and stroke (not common)

In some cases, the immune reaction is less severe and these patients typically have a better outcome.

A: How do you ASSESS the patient with AFE?

• Assess your ABC’s – AIRWAY, BREATHING, CIRCULATION! 
• Full set of vitals – especially BP, HR, and O2 saturation
• Hemodynamic monitoring may be utilized
• ECG
• Fetal heart rate monitoring
• Assess for signs of bleeding which can occur at any site of an invasive procedure (even an IV placement), in the uterus, and at any surgical incisions. Blood can pool under the patient, so always do a thorough assessment.

T: What TESTS will be ordered for AFE?

• Coagulation studies – DIC is a key abnormality in AFE. Coagulation studies will show an elevated D-Dimer, low fibrinogen levels, prolonged PT and PTT in later stages, increased INR.
• CBC 
  • Hbg/hct will be low due to hemorrhage
  • Platelets will be low due to depletion in DIC
  • WBC may be elevated
• Type & Screen – This patient will require blood products such as platelets, cryoprecipitate, FFP or PRBCs.
• Arterial blood gas usually reveals hypoxemia and hypercapnia. If the patient has suffered a cardiac arrest or prolonged hypotension, the ABG will show metabolic acidosis.
• 12 Lead ECG – Conducted to evaluate cardiac dysrhythmias.
• Echocardiogram – This ultrasound of the heart will typically show reduced LV ejection fraction due to the damage incurred in cardiac arrest as well as increased pulmonary pressures.
• Tests to rule out other causes for cardiopulmonary dysfunction can include liver function tests, electrolytes, BUN, creatinine, troponin I, BNP and chest x-ray.

Note that many other conditions can mimic AFE. These include hemorrhage secondary to uterine atony, placental abruption resulting in DIC, pulmonary embolism resulting in obstructive shock, air embolism, septic shock, anaphylactic shock and cardiogenic shock.

T: What TREATMENTS will be provided?

Most patients with AFE will experience cardiac arrest which requires prompt ACLS protocols and CPR at a rate of 100 bpm with full chest recoil and minimal interruptions. One individual will be responsible for manually displacing the uterus during compressions in order to improve cardiac preload. This maneuver relieves pressure placed on the vena cava by the uterus when in a supine position. 

Other interventions include:

• Emergent cesarean section may improve the chances of resuscitation in the mother and increase survival for the baby as well.
• If no pulse is present after four minutes of CPR, a perimortem cesarean is conducted with a goal of having the baby delivered within five minutes of the cardiac arrest.
• Administer tranexamic acid for DIC, which is usually administered as 1 gram given over 10 minutes intravenously.
• In severe hemorrhage, administer fluids until blood products are available, then administer PRBCs as needed.
• Administer platelets, FFP and cryoprecipitate as needed.
• Administer fluid boluses for hypotension and continuously monitor the patient for signs of pulmonary edema.
• Administer medications to improve blood pressure as ordered by the MD: 
  • Norepinephrine – a vasopressor used to increased blood pressure
  • Dobutamine or milrinone – positive inotropes that help the heart contract more strongly
  • Epoprostenol or sildenafil – pulmonary vasodilators to help reduce pulmonary pressures so the right ventricle can work more effectively
• Maintain SpO2 greater than 94%. Most patients will require mechanical ventilation.
• ECMO may be considered in patients that do not respond to mechanical ventilation, in cases where oxygenation is needed for fetal delivery, and in cases of prolonged cardiac arrest.
• Intralipid (an intravenous fat emulsion) is currently being studied as a possible treatment in AFE. Studies suggest it prevents and reverses pulmonary hypertension and subsequent right ventricular failure. More work is being done in this area and is definitely something to monitor if you are working in labor & delivery.

E: How do you EDUCATE the patient/family?

• Amniotic fluid embolism can be incredibly distressing and overwhelming to family members. If possible, assign someone to keep the family updated during the resuscitation attempt. 
• Debrief the family after the event and consider having a hospital chaplain present where appropriate. What should have been a happy and joyous time can quickly become a time of intense grief, anger, sorrow, and disbelief. 
• If the patient or the baby survive, teach the family of the risk for neurological impairment and that this will be irreversible.
• For patients who survive, assure them that they did not do anything to cause AFE to occur.
• For patients who would like to have another baby, successful pregnancy after AFE is possible. 
• The risk of AFE recurring is unknown as no recurrences have yet been reported.
• Provide information on support groups like the ones hosted by the AFE foundation which can be found at AFEsupport.org. 

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References:

AFE Foundation. (2022). What is an Amniotic Fluid Embolism? Amniotic Fluid Embolism Foundation. https://afesupport.org/what-is-amniotic-fluid-embolism/

Baldisseri, M., & Clark, S. L. (n.d.). Amniotic fluid embolism—UpToDate. Retrieved September 18, 2022, from https://www.uptodate.com/contents/amniotic-fluid-embolism?search=amniotic%20fluid%20embolism&source=search_result&selectedTitle=1~46&usage_type=default&display_rank=1#H4

Clark, S. L. (2018). Managing obstetric emergencies: Anaphylactoid syndrome of pregnancy (aka AFE). Contempory OB/GYN, 64(7). https://cdn.sanity.io/files/0vv8moc6/contobgyn/d12c7111a02d78e3007500cc23782977822ef61a.pdf/obgyn0718_ezine.pdf

Combs, C. A., Montgomery, D. M., Toner, L. E., & Dildy, G. A. (2021). Society for Maternal-Fetal Medicine Special Statement: Checklist for initial management of amniotic fluid embolism. American Journal of Obstetrics and Gynecology, 224(4). https://doi.org/10.1016/j.ajog.2021.01.001

Holman, H. C., Williams, D., Sommer, S., Johnson, J., Wheless, L., Wilford, K., McMichael, M. G., & Barlow, M. S. (2019). RN Maternal Newborn Nursing (11.0). Assessment Technology Institute.

Igor, G. (n.d.). INTRALIPID Rescue of Amniotic Fluid Embolism: From Theory to Existence. 4.

Kaur, K., Bhardwaj, M., Kumar, P., Singhal, S., Singh, T., & Hooda, S. (2016). Amniotic fluid embolism. Journal of Anaesthesiology, Clinical Pharmacology, 32(2), 153–159. https://doi.org/10.4103/0970-9185.173356

Leung, L. (n.d.). Evaluation and management of disseminated intravascular coagulation (DIC) in adults—UpToDate. Retrieved September 18, 2022, from https://www.uptodate.com/contents/evaluation-and-management-of-disseminated-intravascular-coagulation-dic-in-adults?search=amniotic%20fluid%20embolism&topicRef=1591&source=see_link

Perry, S. E., Lowdermilk, D. L., Cashion, K., Alden, K. R., Hockenberry, M. J., Wilson, D., & Rodgers, C. C. (2018). Maternal Child Nursing Care (E. F. Olhansky, Ed.; Sixth). Elsevier.