Abstract
Background
The Society of Thoracic Surgeons Workforce on Critical Care and the Extracorporeal Life Support Organization sought to identify how the coronavirus disease 2019 (COVID-19) pandemic has changed the practice of venoarterial (VA) and venovenous (VV) extracorporeal membrane oxygenation (ECMO) programs across North America.
Methods
A 26-question survey covering 6 categories (ECMO initiation, cannulation, management, anticoagulation, triage/protocols, and credentialing) was emailed to 276 North American Extracorporeal Life Support Organization centers. ECMO practices before and during the COVID-19 pandemic were compared.
Results
Responses were received from 93 (34%) programs. The percentage of high-volume (>20 cases per year) VV ECMO programs increased during the pandemic from 29% to 41% (P < .001), as did institutions requiring multiple clinicians for determining initiation of ECMO (VV ECMO, 25% to 43% [P = .001]; VA ECMO, 20% to 32% [P = .012]). During the pandemic, more institutions developed their own protocols for resource allocation (23% before to 51%; P < .001), and more programs created sharing arrangements to triage patients and equipment with other centers (31% to 57%; P < .001). Direct thrombin inhibitor use increased for both VA ECMO (13% to 18%; P = .025) and VV ECMO (12% to 24%; P = .005). Although cardiothoracic surgeons remained the primary cannulating proceduralists, VV ECMO cannulations performed by pulmonary and critical care physicians increased (13% to 17%; P = .046).
Conclusions
The Society of Thoracic Surgeons/Extracorporeal Life Support Organization collaborative survey indicated that the pandemic has affected ECMO practice. Further research on these ECMO strategies and lessons learned during the COVID-19 pandemic may be useful in future global situations.
Graphical abstract
In Short.
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This study demonstrates the evolution of extracorporeal membrane oxygenation practice before and during the COVID-19 pandemic.
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More centers created protocols for sharing equipment and triaging patients based on local or regional resources.
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Research on changes in extracorporeal membrane oxygenation strategies during the COVID-19 pandemic may be beneficial in future global situations.
Extracorporeal membrane oxygenation (ECMO) has played an evolving role in treating respiratory failure during the coronavirus disease 2019 (COVID-19) pandemic as a bridge to lung recovery or transplantation.1, 2, 3, 4 The personnel and resources for ECMO during the pandemic were limited globally.3,5 How the pandemic changed institutional workflow and systems processes has not been extensively studied. The lessons learned may improve preparation for future pandemics.3,6
To assess the impact of COVID-19 on ECMO management, members of The Society of Thoracic Surgeons (STS) Workforce on Critical Care and Extracorporeal Life Support Organization (ELSO) created a survey of ECMO practice in North American ECMO centers. We hypothesized that practice management had changed during the course of the pandemic.
Material and Methods
Survey Development
An expert panel of ELSO and STS Workforce on Critical Care members developed a cross-sectional survey comprising 26 questions covering 6 categories: ECMO initiation, cannulation, management, anticoagulation, triage/protocols, and credentialing. ELSO and STS Executive Leadership provided approval (Supplemental Table 1). ECMO programs were considered low or high volume on the basis of annual cannulations; the threshold number was 20 per year (low volume, ≤20; high volume, >20).1,7 The pre-COVID period was defined as 2019; the COVID period was from 2020 to May 2021, when the survey was completed.
Survey Administration
The survey was emailed in May 2021 to the program directors of the 276 North American adult ECMO programs registered with ELSO. Two emails were sent during a 2-week period before survey closure. The Baylor College of Medicine institutional review board deemed this study did not constitute human subject research.
Statistical Analysis
The analysis compared practices before COVID and during the pandemic; the findings were stratified into 6 categories. Specific data were stratified by institutional ECMO volumes (large vs small programs) and hospital type (academic vs private). For comparisons (pre-COVID vs COVID periods), a McNemar or Bowker test (where appropriate) was used for observations that had a response at each time point. P < .05 was considered significant. Analysis was performed with SAS 9.4 software (SAS Institute).
Results
Of the 276 North American ECMO programs surveyed, the response rate was 34% (n = 93). Of respondents, 63% (n = 62) described their programs as academic, and 80% (n = 78) identified as only adult ECMO programs (Supplemental Table 1).
The number of venovenous (VV) programs considered high volume (>20 cases per year) increased from 29% (n = 25) to 41% (n = 36) after the pandemic started (P < .001; Figure 1). During the pandemic, 23% (n = 20) of VV programs performed 21 to 50 cases; 18% (n = 16) performed >50 cases per year. Overall venoarterial (VA) ECMO volume was minimally affected.
Figure 1.
The proportion of high-volume programs (>20 cases per year) for venovenous (VV) extracorporeal membrane oxygenation (ECMO) increased after the pandemic started.
Initiation
Before the pandemic, most programs relied on 1 or 2 people for cannulation decision for VA ECMO or VV ECMO (Figure 2). During COVID, more institutions involved multiple decision makers for initiating ECMO. The percentage of institutions using ≥3 clinicians during COVID increased from 25% before the pandemic to 43% (P = .001) for VV ECMO and from 20% to 32% (P = .012) for VA ECMO (Figure 2).
Figure 2.
The proportion of institutions using ≥3 clinicians to determine initiation of venoarterial (VA) and venovenous (VV) extracorporeal membrane oxygenation (ECMO) increased during the pandemic.
Utilization/Cannulation
The number of programs with a dedicated cannulation team for VA ECMO (59% [n = 54] vs 60% [n = 55]; P = .317) and VV ECMO (60% [n = 53] vs 61% [n = 54]; P = .317) did not change.
Cardiothoracic surgeons performed most cannulations, but the proportion of cannulations performed by pulmonary and critical care physicians increased during the pandemic (from 13% [n = 12] to 17% [n = 16]; P = .046; Supplemental Table 2).
Most programs (74% [n = 68]) reported that >50% of patients undergoing VA ECMO were cannulated peripherally. The preference for VV canulation changed during the pandemic, with an increase in the use of multisite (57% [n = 51]) over single-site dual lumen cannulation (43% [n = 39]; P = .007).
Management
During the pandemic, the number of centers that reported caring for ECMO patients in a single dedicated unit decreased from 61% (n = 57) to 35% (n = 33; P < .001).
Unfractionated heparin was the preferred anticoagulant before the pandemic for both VA and VV circuits (87% [n = 81] and 85% [n = 78], respectively). This shifted toward the use of direct thrombin inhibitors during the pandemic for VA ECMO from 13% (n = 12) to 18% (n = 17; P = .025) and for VV ECMO from 12% (n = 11) to 24% (n = 22; P = .005).
Resource Allocation
The increased ECMO demand resulted in more programs developing intrahospital resource allocation protocols (from 23% before COVID to 51% during COVID; P < .001). This was seen for VA ECMO and VV ECMO and high-volume and low-volume programs (Figure 3). Regional cooperation in sharing equipment and coordinating interhospital patient transfer increased from 31% to 57% (P < .001) during the pandemic (Figure 4); increases were seen for VA ECMO and VV ECMO programs and low-volume and high-volume programs (Figure 4).
Figure 3.
The number of large-volume and small-volume venoarterial (VA) and venovenous (VV) extracorporeal membrane oxygenation (ECMO) programs that developed intrahospital resource allocation protocols increased during the pandemic.
Figure 4.
The number of large-volume and small-volume venoarterial (VA) and venovenous (VV) extracorporeal membrane oxygenation (ECMO) programs that developed interhospital regional and local triage agreement strategies for resource allocation increased during the pandemic.
Credentialing
Most programs did not change the credentialing process once the pandemic started (Supplemental Table 3). A formal review process for complications related to ECMO increased from 78% (n = 70) to 82% (n = 75; P = .046).
Comment
Our survey results highlight several key changes in ECMO utilization and practice in North America: programs performing >20 VV ECMO cases per year (high-volume centers) increased; the number of clinicians determining the eligibility of ECMO initiation increased; resource allocation and triage protocols for ECMO were developed for use within individual centers and for regional cooperation between centers; the demand for ECMO resulted in more hospitals having to care for ECMO patients in multiple units; and the use of direct thrombin inhibitors increased.
The increase in the proportion of high-volume VV ECMO programs reflects increased demand for ECMO for respiratory failure. As a result, high-volume centers may have reached their capacity limit, forcing low-volume ECMO centers to expand their capacity. This increased demand changed ECMO practices during the pandemic, with a doubling of centers reporting that VV ECMO patients were cared for in multiple units.
The proportion of centers involving 3 or more providers in the decision to initiate ECMO increased during the pandemic. This probably reflects increased ECMO demand for COVID-19 respiratory failure and shared decision for appropriate oversight of resources and triaging.
Survey respondents identified large changes to intrahospital and interhospital resource reallocation of ECMO circuits and personnel and the interhospital transfer of ECMO patients.3,5 The number of programs triaging ECMO patients or equipment with other institutions based on available local or regional resources significantly increased compared with before COVID. As the number of patients with COVID-19 surged, ECMO simultaneously became both an expectation for severe acute respiratory distress syndrome and an increasingly limited resource.3,5 Our findings also showed a substantial increase in programs that developed resource triage protocols within their institutions. These processes may help prepare for future pandemics.5
Cardiothoracic surgeons remained the primary proceduralists for VV ECMO cannulation; however, during the pandemic, more pulmonary and critical care physicians performed cannulations. Many programs reported a significant increase in the use of multisite (femoral and internal jugular) over single-site (internal jugular or subclavian dual lumen) cannulation. This probably reflects a shift in the population of patients from those with chronic lung diseases (pre-COVID) to those with higher acuity acute respiratory distress syndrome during the pandemic who needed urgent bedside cannulation.2,3,7
COVID-19 is associated with severe vascular complications and hypercoagulability, with a high incidence of heparin-induced thrombocytopenia after therapeutic anticoagulation.8 The use of direct thrombin inhibitors in VV ECMO and VA ECMO increased, despite the increase in cost compared with heparin.9
This study has several limitations. First, some management changes may have occurred as part of a program’s natural development and not the pandemic. Second, only ELSO-registered programs were included in the survey. Third, the response rate of this survey was only 34% but compares favorably with the 9% to 19% response rate from 3 previous STS surveys.10 Although approximately 60% of overall respondents represented academic programs, a larger survey response rate may have altered some of the results by changing the distribution of respondents. Nevertheless, approximately 40% of programs reported fewer than 10 VA or VV ECMO cases annually, whereas 20% reported performing more than 50 VA or VV ECMO cases annually; these results suggest that the survey encompassed a reasonable cross-section of North American ECMO programs. Fourth, the definition of low-volume vs high-volume centers was somewhat arbitrary; stratifying sites by very high volume (>50 cases per year) may have yielded different results. COVID surges differed in timing and intensity on the basis of geography and urban/rural location of centers, which may have affected participant responses. Finally, care models of daytime and night-time ECMO coverage were not identified, which may have affected practice patterns.
In conclusion, this survey demonstrates the evolution of ECMO practice before and during the COVID-19 pandemic. More high-volume VV ECMO centers developed, and more centers created protocols for sharing equipment and triaging patients based on local or regional resources. Anticoagulation management is evolving with increased use of direct thrombin inhibitors.
Acknowledgments
The Supplemental Tables can be viewed in the online version of this article [https://doi.org/10.1016/j.atssr.2022.10.017] on http://www.annalsthoracicsurgery.org.
The authors thank members of the STS Workforce on Critical Care for reviewing the manuscript and Rebecca Bartow, PhD, of Texas Heart Institute’s Scientific Publications for editorial contributions.
Funding Sources
The authors have no funding sources to disclose.
Disclosures
Rita Milewski reports a relationship with Destiny Pharma Ltd that includes: board membership. Subhasis Chatterjee reports a relationship with Edwards Lifesciences that includes: board membership. Subhasis Chatterjee reports a relationship with La Jolla Pharmaceutical Company that includes: board membership. Subhasis Chatterjee reports a relationship with Baxter Pharmaceutical Products that includes: board membership. Subhasis Chatterjee reports a relationship with Eagle Pharmaceutical Inc that includes: board membership. HelenMari Merritt-Genore consults for AtriCure. Glenn J. Whitman reports a relationship with Avania/Cellphire: Executive Board Member. Rakesh C. Arora reports a relationship with Edwards LifeSciences, AVIR Pharma Inc, HLS Therapeutics, all honoraria for Ad Board work.
Supplementary Data
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