key: cord-0878112-1o5cca52
authors: Blazoski, Cameron M.; Baram, Michael; Yang, Qiong; Hirose, Hitoshi
title: Outcomes of extracorporeal membrane oxygenation in influenza versus COVID‐19 during the first wave of COVID‐19
date: 2021-08-09
journal: J Card Surg
DOI: 10.1111/jocs.15888
sha: a07b6c839f895513dfd25edf5ad2f41de86afe58
doc_id: 878112
cord_uid: 1o5cca52

PURPOSE: Extracorporeal membrane oxygenation (ECMO) is a refractory treatment for acute respiratory distress syndrome (ARDS) due to influenza and severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2, also referred to as coronavirus disease 2019 [COVID‐19]). We conducted this study to compare the outcomes of influenza patients treated with veno‐venous‐ECMO (VV‐ECMO) to COVID‐19 patients treated with VV‐ECMO, during the first wave of COVID‐19. METHODS: Patients in our institution with ARDS due to COVID‐19 or influenza who were placed on ECMO between August 1, 2010 and September 15, 2020 were included in this comparative, retrospective study. To improve homogeneity, only VV‐ECMO patients were analyzed. The clinical characteristics and outcomes were extracted and analyzed. RESULTS: A total of 28 COVID‐19 patients and 17 influenza patients were identified and included. ECMO survival rates were 68% (19/28) in COVID‐19 patients and 94% (16/17) in influenza patients (p = .04). Thirty days survival rates after ECMO decannulation were 54% (15/28) in COVID‐19 patients and 76% (13/17) in influenza patients (p = .13). COVID‐19 patients spent a longer time on ECMO compared to flu patients (21 vs. 12 days; p = .025), and more COVID‐19 patients (26/28 vs. 2/17) were on immunomodulatory therapy before ECMO initiation (p < .001). COVID‐19 patients had higher rates of new infections during ECMO (50% vs. 18%; p = .03) and bacterial pneumonia (36% vs. 6%; p = .024). CONCLUSIONS: COVID‐19 patients who were treated in our institution with VV‐ECMO had statistically lower ECMO survival rates than influenza patients. It is possible that COVID‐19 immunomodulation therapies may increase the risk of other superimposed infections.

Adult patients who were confirmed to have influenza or who underwent ECMO at our institution from August 1, 2010 to September 15, 2020 were included in this study. Patients were identified within an IRB-approved, prospectively maintained ECMO database (IRB approval #11D.185). Data from these patients were retrospectively extracted and details were further studied by In the influenza group, we may offer VV-ECMO in a morbidly obese patient via the right internal jugular vein using Avalon cannula as long as the patient's neck anatomy is feasible for cannulation; however, in the COVID-19 group, we no longer offer VV-ECMO in morbidly obese patients since we typically do not use the Avalon cannula in COVID-19 patients. b We did not offer mobile ECMO (when our ECMO team travels to outside hospitals to initiate cannulation and transport the patient back to our institution on ECMO) in outside-of-network hospitals for COVID-19 patients, while we could offer this to influenza patients. reviewing medical records. Inclusion criteria included a positive COVID-19 test and a diagnosis of ARDS. ECMO placement was determined by a multidisciplinary team that included a cardiac surgeon, a pulmonary critical care physician, and a cardiovascular intensivist.

The indications for ECMO placement were the same as those listed in our previous paper, 26 and Table 1 includes the list of contraindications for ECMO placement in COVID-19 patients. The exclusion criteria for COVID-19 patients may be more restrictive than in non-COVID-19 patients, due to the limited resources available during the first wave of the pandemic and challenges due to increased isolation needs.

During the first wave, our institution did not utilize venoarterial ECMO (VA-ECMO) in patients with COVID-19, due to limited resources and an unclear understanding of the reversibility of the disease. In influenza patients, seven patients were placed for VA-ECMO for cardiac dysfunction or severe vasoplegia. However, these VA-ECMO patients were excluded from this study to ensure the appropriate comparisons.

Due to resource allocation and isolation concerns, COVID-19 and influenza patients were treated differently. For VV-ECMO, we traditionally used a single double-lumen cannula (Avalon© cannula;

Avalon Laboratories, Rancho Dominguez), but this had to be modified for COVID-19. Since the Avalon cannula placement always requires fluoroscopy and echocardiography, which requires additional personnel including radiology technicians and an echocardiography technician, the utilization of the Avalon© cannula was discouraged due to concern of the additional exposure of personnel and equipment. 26 In COVID-19 patients, VV-ECMO was placed using the femoral and internal jugular veins ( Figure 1 ). This change in insertion practice did not result in procedural complications, but it did affect body mass index restrictions. All cannulation was performed in the intensive care unit (ICU) without transport to either the operating room or catheterization lab unless an issue occurred during the bedside cannulation.

Due to the COVID-19 pandemic, our institution did not offer a mobile ECMO program (when our ECMO team travels to outside hospitals to initiate cannulation and transport the patient back to our institution on ECMO) outside of our hospital network to avoid a possible exposure of required personnel including the ECMO surgeon, perfusionist, and transfer nurses at the local site, while mobile ECMO was offered for patients with influenza. Instead of activating mobile ECMO cannulation teams, we encouraged local cardiac surgeons to place ECMO at their institutions and then transport the patient to our facility.

The general management of ECMO has been described in one of our prior papers. 27, 28 Briefly, after placement of ECMO, the ventilator was set to the ARDSnet protocol. 18 Anticoagulation protocol differed between the two groups. In the influenza group, a heparin drip was initiated the day following cannulation with a goal PTT of 45-55 sec. If bleeding complications were observed the heparin drip was held until the bleeding was controlled. In the COVID-19 group, a heparin drip was started if PTT fell below 50 s after cannulation and was maintained at an anti-Xa level of 0.3-0.5 IU/ml. Xa was used instead of PTT, since Xa was more reliable for anticoagulation in COVID-19 patients. 31 If bleeding complications were observed in COVID-19 patients, the anticoagulation was held and then restarted at a lower anti-Xa goal of 0.1-0.3 IU/ml.

The timing of the decannulation was determined by chest X-ray findings, lung mechanics, and gas exchange. Before decannulation, the sweep gas was discontinued for at least 24 h to ensure the lungs were able to exchange oxygen and carbon dioxide appropriately. For COVID-19 cases, we encouraged bed-side decannulation and discouraged transporting to the operating room to limit exposure to Our study is limited by its small sample size and being based in one hospital center that provided ECMO support for a 12 hospital health system. It is also possible that there was selection bias in this study, even though ECMO placement was determined by a multidisciplinary team of physicians. Moreover, influenza patients dated back to 2010, while all COVID-19 patients were treated in 2020; it is possible that changes in ECMO protocol due to COVID-19 and associated treatment protocols with ECMO could impact patient outcomes and complication rates.

Despite its limitations, this study provides significant data on 28 patients with COVID-19 and effectively compares patients with ARDS due to COVID-19 to patients with ARDS due to influenza. This paper is one of a growing number of studies on COVID-19, and we hope that our findings contribute to a better understanding of how to effectively treat COVID-19.

Based on our results, we conclude that there are significant differences in the use of VV-ECMO in treating ARDS due to COVID-19 to treating ARDS due to influenza. COVID-19 patients appear to be at a higher risk of bacterial superinfection, and prevention and control of bacterial infections may be critical in improving survival. More research is needed to understand the efficacy and risks of using ECMO to treat cases of COVID-19.

Hitoshi Hirose https://orcid.org/0000-0001-5210-810X

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