EXECUTIVE SUMMARY

Emergency clinicians are adept at diagnosing and treating pulmonary embolisms (PE). In cases deemed intermediate- or high-risk, determining which treatment is best is not always clear. Innovators at Massachusetts General Hospital developed the first pulmonary embolism response team (PERT), which has since been adopted widely.

  • A PERT is a multidisciplinary panel of specialists who rapidly respond to PE cases that present complex challenges to the treating clinician.
  • PERTs can be activated from anywhere, but experts note 60% of PERT calls start in the emergency setting.
  • Emergency physicians serve as valuable participants on PERTs, considering they diagnose and treat so many PEs.
  • Studies have shown PERTs produce improved outcomes, but there is a big push to centralize data collection on PERT cases so the benefits can be documented better, and care can be optimized.

Data suggest as many as 900,000 people in the United States experience a pulmonary embolism (PE) or deep vein thrombosis (DVT) event every year, with 60,000 to 100,000 individuals dying from their condition. In fact, 10% to 30% of patients with PE or DVT die within one month of diagnosis.1

These conditions certainly are well-known to emergency physicians, many of whom have become highly skilled in both the diagnosis and treatment of PE and DVT. However, for patients with intermediate- or high-risk thromboembolisms, treatment often requires more than anticoagulation therapy. But precisely how to proceed is not always clear.

Nonetheless, with time to treatment a critical factor, how does the frontline provider expedite the kind of multidisciplinary insight needed to reach a sound treatment decision? Innovators at Massachusetts General Hospital (MGH) devised their own solution to this dilemma with the creation of the first pulmonary embolism response team (PERT) in 2012.

Akin to other rapid response mechanisms, a PERT activation quickly assembles a team of experts from multiple specialties so an informed treatment decision can be made quickly. In fact, the concept has worked so well at MGH that it has been adopted by medical centers across the United States and even globally.

Furthermore, at least in the United States, emergency medicine physicians play a central role in the PERT process, explains Christopher Kabrhel, MD, MPH, an emergency medicine specialist and director of the Center for Vascular Emergencies at MGH.

“About 60% of PERT activations, not only in our hospital but across the country, come from the ED. That’s because the ED is the most common place for a PE to be diagnosed,” he says. “However, it is important for emergency physicians to also be active members of PERTs. We have an active knowledge and skill set that is useful in helping with the diagnosis, risk-stratification, and treatment decisions [for] patients with PE precisely because we do diagnose so many of them.”

Risk-Stratify

Although the PERT concept has been adopted by many hospitals, not all emergency providers can access a PERT in their institutions. A group called the PERT Consortium, established in 2015, is trying to facilitate wider adoption of the concept while also collecting data and pushing improvements in PE care.2

Rachel Rosovsky, MD, MPH, vice president of the PERT Consortium, described the evolution of PE care in recent years during a March 11 presentation sponsored by the CDC.

For patients with acute PE, she said anticoagulation saves lives, but stressed therapy must start early. To learn which patients would benefit from more advanced therapies beyond anticoagulation, Rosovsky said patients must be risk-stratified.

For instance, patients at high risk of dying from PE are hemodynamically unstable, meaning their blood pressure is low, there is a clear strain on the heart, the right ventricle shows dysfunction, and troponin levels are elevated.

“These patients clearly need something beyond anticoagulation. They need primary reperfusion,” Rosovsky indicated, referring to advanced therapies aimed at restoring blood flow through or around blocked arteries.

The next risk category is intermediate, divided into intermediate-high and intermediate-low. Patients in this group typically record normal blood pressure, but there are signs of right ventricular strain on their heart, revealed through either an echocardiogram or a CT scan, and elevated cardiac troponin levels.

“Intermediate-high is when patients have evidence of right heart strain on both of those modalities [CT/echo and troponin levels], and intermediate-low is when they have evidence of right heart strain on just one of those [modalities],” Rosovsky said. “These [intermediate-risk] patients definitely need anticoagulation, and there is a subset that may benefit from rescue reperfusion therapy.”

Patients at low risk do not show problematic blood pressure levels or any evidence of heart strain. “These patients need anticoagulation and often can be discharged early,” Rosovsky said.

For intermediate-risk and high-risk patients, it often is unclear what, if any, advanced therapies should be employed. Rosovsky said this is caused in part by a lack of quality comparative data, the rapid advancement of interventional tools in recent years, and conflicting guideline recommendations.

Consequently, before the implementation of the PERT at MGH “the lead patients for treatment really depended on who got called and where they were in the hospital,” Rosovsky said. “There was no consistency in decision-making and there was ... no single team or acceptable algorithm. There was really no systemic way that we were evaluating our results.”

All these factors figured into the creation of the first PERT, which today includes representatives from vascular medicine, emergency medicine, hematology/oncology, interventional cardiology, vascular surgery, radiology, pharmacy, interventional radiology, non-interventional cardiology, cardiac surgery, and pulmonary/critical care. Sometimes, even the patient or family members take part in a PERT call.

“Anyone in the hospital can activate the PERT if they are concerned about a patient with PE or even a patient with a suspected severe PE,” Kabrhel explains. “For example, some patients present with a likely PE, but they are too unstable to undergo imaging, and we activate a PERT.”

There is a specific number used to activate PERT. That number is well publicized throughout the hospital, along with some indications for activation. A PERT fellow, who often is an interventional cardiology, vascular medicine, or pulmonary fellow, will respond to the page, gather some basic information, and activate the rest of the multidisciplinary team by sending a group page and an email that includes a link to an online meeting.

The meetings are scheduled to take place promptly, typically within just a few minutes, to discuss the case. Further, during the conference call, participants can access a patient’s imaging and lab results.

Kabrhel describes one recent case that involved a woman in the later stages of pregnancy who was beginning to contract. She was diagnosed with a large, central PE and right heart strain.

“The PERT got activated, and I was one of the people who responded,” he shares. “The question was how to deal with the patient’s PE in the setting of her impending delivery.”

It was a difficult case because clinicians knew once the woman was in active labor, she would start to bear down, and she would ultimately become less stable.

“We knew that we couldn’t do a spinal or epidural anesthetic in order to do a C-section. She needed to be on blood thinners, and that was, therefore, contraindicated,” Kabrhel says. “Yet, we also knew if we were to intubate her and plan to do an operative C-section, the process of intubation acts much the same way as the process of bearing down in labor does. It [would] decrease blood flow to the heart, and there is a good chance she would code during that process.”

Making the multidisciplinary PERT available enabled clinicians to evaluate all the complexities of the patient’s care.

“My contribution, for example, was understanding what happens to patients when you emergently intubate them and what happens to their physiology in the setting of a large PE,” Kabrhel says.

Ultimately, clinicians decided to take the patient to the cardiac surgery operating room. She would be intubated, but only once the cardiac surgeons and the critical care intensivists were at the bedside and prepared to put her on cardiac bypass.

“We anticipated that with intubation, which we unfortunately couldn’t avoid, the patient might become unstable. We prepared for that by being able to put her on bypass emergently without any delay, which could result in hypertension or brain damage,” Kabrhel explains.

The event proceeded precisely as clinicians expected: The woman was intubated, she became unstable, and was placed on cardiac bypass.

“An emergency C-section took place, and the baby was delivered and is doing fine,” Kabrhel reports. “The woman has since undergone a percutaneous thrombectomy with our interventional cardiology and vascular medicine team [to break up or remove the PE].”

This case is a good illustration of how multiple specialists involved with a PERT can contribute to a complex case, providing the best chance for a good outcome.

MGH has collected data to show how the PERT process has elevated care and outcomes for PE patients overall. For instance, Rosovsky shared data showing that before the implementation of PERT, the 30-day mortality rate for patients who presented to the hospital with a PE was on the rise. However, this trend reversed once PERT was implemented.3

Rosovsky noted other medical centers that have implemented PERT have reported positive results, too, although she acknowledged not every single-center study has demonstrated such positive outcomes.4

Address Buy-In

Are there enough resources at every facility to assemble a PERT approach? Kabrhel says roughly 30% of PERTs are in community hospitals.

“No one expects that every community hospital is going to have access to ECMO, advanced cardiac surgery, or even some of these newer catheter-based thrombectomy devices that the large academic medical centers have,” Kabrhel explains. “However, a lot of PERT patients are treated with anticoagulation alone, and many receive catheter-directed thrombolysis that can be done at small hospitals."

Kabrhel adds that when creating a PERT at a small facility, it is easy to liaise with a larger hospital, either for a virtual PERT consultation or a network transfer to places with the right resources to take care of a patient. “PERT can happen anywhere, with the recognition that there will be occasional patients who need to be transferred to other academic centers,” Kabrhel says.

A PERT requires an activation system; at MGH, that is as simple as a phone number. “Hospitals have these for other things. They have rapid response teams for codes, and they have STEMI teams. We just copied that.”

Facilities have to activate several specialties simultaneously, but Kabrhel argues that is not complicated. “Simply sending out a Zoom link for a multidisciplinary meeting after you receive a page about it is commonplace,” he explains.

What may be complicated is securing buy-in from various specialties. Some clinicians might be concerned another specialist is going to dictate how they should manage PE. “There are different approaches among different specialties in terms of what they think the optimal management of PE is. There is sometimes reluctance on the part of participants to join a [PERT] if they think they will now be going to have to adopt someone else’s algorithms,” Kabrhel observes.

Still, Kabrhel stresses this kind is not what PERT is about. “PERT is a process, it is not a protocol,” he says. “The benefit of PERT comes from the discussion among specialists who have different opinions, different literature bases, and different biases. The ability to openly discuss the best treatment for a patient among people with whom you may not agree, I think, results in the best care.”

Most often, the hurdles are about overcoming egos and achieving cooperation among people who are fearful they are going to be told what to do. In reality, everyone will be asked to give their opinions. “Focus on the fact that we want people with different opinions, and we value those different opinions,” Kabrhel adds.

Engage the Patient

If there are differing opinions, how does a PERT decide which treatment is best? In most cases, PERT participants reach a consensus on how to proceed. “There are occasional cases where there are differences of opinion. In those instances, whenever it is possible, we try to leave [the decision] up to the patient,” Kabrhel says. “We believe in shared decision-making.”

Typically, clinicians tell the patient about treatment options, including supportive data as well as pros and cons. “In those instances when we have had patients or their families or their primary care physicians participate in the multidisciplinary call, it has always been a positive experience,” Kabrhel says. “The patient realizes just how much thought and care is going in to the treatment decisions that are being made.”

Over the past year, blood clots associated with COVID-19 have added another layer of complexity for clinicians, including the MGH PERT. “Initially, we were getting activated a lot because of COVID-related thromboses, and no one knew what to make of that,” Kabrhel explains. “The types of patients we care for in the ED ... go from being a diversity of patients to being predominantly COVID-19 [patients], and then trickling back to something that seems a little more like normal.”

Also, there has been ample debate over where and how various COVID-19-related clots originated, and how the PERT should respond. “We had to evolve just like everybody in medicine,” Kabrhel says. “We certainly are still busy and active. It was ... a moving target over time.”

At MGH, the PERT activates 12 to 20 times a month, with more than half those activations coming from the ED. “You probably need at least a few [activations] per month in order to inspire people to participate [in a PERT],” Kabrhel says. “[But] it may only take one patient for whom activating multidisciplinary care and facilitating access to various resources can be life-saving.”

Consider New Tools

The concept of PERT is consistent and well-understood, but not all PERTs operate similarly. For instance, while a fellow takes the lead in setting multidisciplinary meetings at MGH, most PERTs begin with a call to a specific attending physician who happens to be on call that day. “Then, [that attending physician] will activate the rest of the team,” Kabrhel says.

Not every specialist will be available to respond to each PERT call. “There is enough redundancy that we always have four or five different people and specialists who respond to the call, even though it may not be the same four or five people every time,” Kabrhel says.

Kabrhel regularly encourages colleagues in emergency medicine to take part in the PERT process, noting it is an enriching experience. “The idea of serving on a PERT ... is a little bit unusual,” Kabrhel says. “It can be incredibly rewarding to participate in the care of these complex patients, and to provide advice and expertise that we as emergency physicians have.”

Although PERTs are widespread, the PERT Consortium has collected more data from institutions on the East and West Coasts vs. other areas of the United States. Jeffrey Kline, MD, a professor of emergency medicine at Indiana University, says the Midwest tends to be more conservative.

“[Practitioners here] are waiting for clear evidence of effectiveness, which is lacking,” Kline says, adding PERT programs probably make a large difference to a tiny number of patients.

Another reason why PERTs may be less visible in the Midwest is because there are fewer vascular medicine fellowships there, according to Kline. “These fellows often do the majority of the work in East Coast [hospitals]. That said, there is strong representation [in the PERT Consortium] from Indiana, Michigan, Nashville, and Cleveland.”

Kline suggests the biggest technical issue to consider is what the role of the mechanical suction catheter, a tool he refers to as disruptive, will be going forward in the care of PE patients. “I could see 90% of clots treated with this catheter in five years,” he predicts. “Emergency medicine physicians [will] still have a role because many patients are referred [to PERTs] who should not be, and they still need care, if not by the PERT.” 

REFERENCES

  1. Beckman MG, Hooper WC, Critchley SE, Ortel TL. Venous thromboembolism: A public health concern. Am J Prev Med 2010;38:S495-S501.
  2. PERT Consortium. About the PERT Consortium.
  3. Todoran TM, Giri J, Barnes GD, et al. Treatment of submassive and massive pulmonary embolism: A clinical practice survey from the second annual meeting of the Pulmonary Embolism Response Team Consortium. J Thromb Thrombolysis 2018;46:39-49.
  4. Carroll BJ, Beyer SE, Mehegan T, et al. Changes in care for acute pulmonary embolism through a multidisciplinary pulmonary embolism response team. Am J Med 2020;133:1313-1321.e6.