Episode #127 Amniotic Fluid Embolism: Are You Prepared? Part 2

Hello and welcome back to the Anesthesia Patient Safety Podcast.  My name is Alli Bechtel, and I am your host. Thank you for joining us for another show. We are headed back over to the maternity unit today to discuss a critical topic in obstetric anesthesia, amniotic fluid embolism.

Before we dive into the episode today, we’d like to recognize Nihon Kohden America, a major corporate supporter of APSF. Nihon Kohden America has generously provided unrestricted support to further our vision that “no one shall be harmed by anesthesia care”. Thank you, Nihon Kohden America – we wouldn’t be able to do all that we do without you!”

Let’s return to our featured article from the latest October 2022 APSF Newsletter by David Arnolds called, “Recognition and Management of Amniotic Fluid Embolism: A Critical Role for Anesthesia Professionals on Labor and Delivery.” To follow along with us, head over to APSF.org and click on the Newsletter heading. First one down is the current issue. Then scroll down until you get to our featured article today. I will include a link in the show notes as well.

We are going to pick up right where we left off last week with the recognition part of amniotic fluid embolism before moving on to the management. Have you checked out table 1 in the article yet? This includes the diagnostic criteria for research purposes for AFE developed by an expert panel from the Society for Maternal-Fetal Medicine and the Amniotic Fluid Embolism Foundation. Let’s review the criteria now.

1. Sudden onset of cardiorespiratory arrest, or both hypotension with systolic blood pressure <90 mm Hg and respiratory compromise which may include dyspnea, cyanosis, or oxygen saturation, SpO2 < 90%.
2. Overt disseminated intravascular coagulation or DIC following appearance of these initial signs or symptoms. Coagulopathy must be detected prior to loss of sufficient blood to itself account for dilutional or shock-related consumptive coagulopathy.
3. Clinical onset during labor or within 30 min. of delivery of placenta
4. No fever (>38° C) during labor

Arnolds tells us that these criteria were developed to be more specific rather than sensitive so there may be cases of amniotic fluid embolism that do not meet these criteria. There is another set of criteria that may be more sensitive created by an expert panel from the International Network of Obstetric Surveillance Systems. The criteria include the following:

1. Acute cardiorespiratory collapse within 6 hours after labor, delivery or ruptured membranes, with no other identifiable cause
2. Following the acute cardiopulmonary collapse, there is acute coagulopathy in those women who survive the initial event.

The most common reason for cases not meeting the full research criteria was not having or being unable to obtain laboratory evidence for DIC within a certain time frame. Checking labs to evaluate coagulation status may be extremely helpful in managing patients with AFE, but it may not occur or may not occur in the appropriate time frame due to ongoing resuscitation and resource availability.  The keys to remember for the recognition of amniotic fluid embolism in obstetric patients is acute cardiorespiratory collapse without another cause that is associated with acute coagulopathy.

Now it’s time to review the management of these critically ill patients. Keep in mind that some patient with AFE will present with cardiac arrest. When this is the case, the initial management involves high-quality advanced cardiac life support for a pregnant patient. This is outlined by the American Heart Association Scientific Statement on Cardiac Arrest in Pregnancy. Here are the keys for pregnant patients at greater than 20 weeks gestational age:

Left Uterine Displacement

• Prioritize oxygenation and airway management
• Performance of a perimortem cesarean delivery or resuscitative hysterotomy to remove the aortocaval compression to support maternal resuscitation efforts. Keep an eye on the clock or assign someone to be a time-keeper because the perimortem cesarean delivery should be performed within 5 minutes of cardiac arrest if return of spontaneous circulation has not occurred and this is regardless of fetal viability.

Now, what about patients with AFE who do not present with cardiac arrest? Or patients who have return to spontaneous circulation within the 5 minute time frame? These patients often have acute pulmonary hypertension and right ventricular failure as their initial presentation. You will need to act quickly since right ventricular failure may be followed by left ventricular failure and cardiovascular collapse. There is a role for focused cardiac ultrasound either transthoracic or transesophageal performed by a trained anesthesia professional to provide information about heart function, volume status, and the response to therapy. Patients may require norepinephrine or epinephrine administration for vasopressor and inotropic support. Dobutamine or milrinone are other options for inotropic support and inhaled nitric oxide or epoprostenol are pulmonary vasodilators that may be needed to support the right ventricle. Take care with fluid administration in patients with right ventricular dysfunction to avoid fluid overload. Careful volume administration with ongoing assessment of the volume status is critical.

It is important to remember that AFE occurs in obstetric patients who may be removed from the intensive care and operating room setting so the immediate availability of drugs and equipment may be limited. Initial treatment may include phenylephrine and epinephrine while additional resources are obtained. This is a good time to bring out your institution-specific amniotic fluid embolism cognitive aid to identify where the advanced inotropic support and pulmonary vasodilators are and who is responsible for bringing them to the labor and delivery unit quickly.  If you have extracorporeal membrane oxygenation or ECMO at your institution, there should be early consideration to use this resource.

The next phase of presentation and management involves the development of a significant coagulopathy. Management may involve the use of viscoelastic testing to guide transfusion of blood, blood products, and clotting factor concentrates. During a hemorrhage event, empiric ratio-based resuscitation as part of a massive transfusion protocol may need to be followed. There is evidence from several case reports and case series that supports hyperfibrinolysis during AFE. The recommended treatment is administration of tranexamic acid 1g IV given over 10 minutes with consideration for repeat 1g IV 30 minutes later with ongoing bleeding. Another option is administration of fibrinogen concentrate or cryoprecipitate which is associated with improved outcomes. This is supported with the previously established goal during an obstetric hemorrhage to treat the resultant hypofibrinogenemia. Patients with an amniotic fluid embolism are also at risk for uterine atony so be prepared to provide prophylactic and ongoing treatment to help decrease additional blood loss.

Next up, let’s discuss proposed treatments for amniotic fluid embolism. Keep in mind that these were developed from case reports and discussions, but there are no universal recommendations that are supported by evidence at this time. Have you heard the phrase, “A-OK” as a treatment for AFE? This involves administration of the combination of atropine, ondansetron, and ketorolac. Other medications include hydrocortisone, lipid emulsion, and C1 esterase inhibitor, that last one is usually reserved for treatment and prevention of hereditary angioedema.  However, there is no evidence to support the use of these medications for patients with an amniotic fluid embolism.

Check out the case report, “Atypical amniotic fluid embolism managed with a novel therapeutic regimen” that was published in 2017. The authors describe a case of patient with a suspected AFE following cesarian delivery who was treated with atropine 0.2mg, Ondansetron 8mg, and Ketorolac 15mg IV with improvement in hemodynamics. I will include the citation in the show notes as well. The proposed A-OK regimen calls for IV administration of the following medications: Atropine 1mg to treat increased vagal stimulation and improve vasomotor tone, Ondansetron 8mg to block serotonin receptors, and Ketorolac 30mg to decrease thromboxane production. While this proposed treatment strategy may be helpful, it is vital to keep in mind that more research is necessary to determine if this is an effective treatment for AFE. The first step for management must include effective supportive care in order to help keep patients safe.

Last week, we talked about the Society for Maternal-Fetal Medicine Special Statement: Checklist for initial management of amniotic fluid embolism that was published in 2021. This checklist can be used as a cognitive aid during crises management of a patient with an amniotic fluid embolism. I will include the citation in the show notes again this week. The management involves four parts: circulatory collapse, coagulopathy, pulmonary hypertension and right ventricular failure, and post-event debriefing.

Let’s talk a little more about post-event debriefing following an AFE event. Have you been involved in taking care of a patient with an amniotic fluid embolism? Did your team participate in a debriefing session? This is an important step for providing support to all the members of the healthcare team who were involved in the patient’s care. Plus, this is a good time to discuss what went well during the management – For example, was there a hands off team leader who used the amniotic fluid embolism cognitive aid or was a massive transfusion protocol activated appropriately – and to identify opportunities for improvement – For example, needing to make appropriate modifications to the cognitive aid depending on resources availability or developing a clear strategy to activate the ECMO team. Another important step for all cases of suspected AFE is to the contact the Amniotic Fluid Embolism Foundation. I will include the link in the show notes as well. If you head over to the website, the Foundation provides support for the patient and family members. The AFE Foundation is a non-profit organization that was established in 2008 by a survivor of an AFE event to bring together families, healthcare professionals, and researchers with a goal to decrease maternal and infant mortality due to amniotic fluid embolism through support, research, and education initiatives. You can get involved as well by submitting any cases of suspected AFE to the AFE Patient Registry. This registry helps to support research on this rare syndrome with a goal to be able to better recognize, diagnose, treat, and even prevent AFE from occurring in the future.

We made it to the end of the article! The key takeaways for anesthesia professionals on labor and delivery units is that early recognition and high-quality supportive care for patients with amniotic fluid embolism is critical to save lives and decrease morbidity.

Before we wrap up for today, we are going to hear from Arnolds again. I asked his what do you hope to see going forward? Let’s take a listen to what he had to say.

[Arnolds] “Going forward, I hope to see us learn more about the pathogenesis and pathophysiology of amniotic fluid embolism, so we can move from providing high quality supportive care as we currently are to identifying patients at increased risk for this rare disorder and providing them with targeted treatment.”

[Bechtel] Thank you so much to Arnolds for contributing to the show today. We hope to see further research in this area so that we can keep obstetric patients with AFE safe. Education about AFE is also important so go ahead and share this article and podcast series with your colleagues and other healthcare professionals who provide care for obstetric patients.

If you have any questions or comments from today’s show, please email us at [email protected]. Please keep in mind that the information in this show is provided for informational purposes only and does not constitute medical or legal advice. We hope that you will visit APSF.org for detailed information and check out the show notes for links to all the topics we discussed today.

Have you considered applying for the joint APSF-FAER Mentored Research Training Grant? The Letter of Intent submissions for the 2023 grant opened December 1^st and will close on January 1, 2023 so there is still time. This is a two-year, $300,000 award to help anesthesiologists develop skills and preliminary data in order to become independent investigators in the field of anesthesia patient safety. The first step is the letter of intent prior to submitting a full application. So, what are you waiting for? Get your letter of intent in! I will include a link to the submission page in the show notes as well. You might be the next anesthesia patient safety researcher!

Until next time, stay vigilant so that no one shall be harmed by anesthesia care.

© 2022, The Anesthesia Patient Safety Foundation