San Diego—New research has highlighted the important role that venovenous extracorporeal membrane oxygenation (VV ECMO) can play in critically ill COVID-19 patients who do not respond to conventional respiratory therapy.
The chart review found that the overwhelming majority of these patients were successfully discharged to long-term acute rehabilitation or home, leading the researchers to recommend use of the therapeutic strategy in this otherwise fragile patient population.
“At the beginning of the COVID-19 pandemic in early 2020, we weren’t really sure of the best way to treat the disease,” said Sarah Sun, BS, a medical student at Rush Medical College, in Chicago. “While several international organizations suggested the use of ECMO to help with these patients, we didn’t have enough data at the time to see if it actually worked.”
To help answer this question, the investigators reviewed the charts of 21 patients (median age, 45 years; 15 males) with confirmed COVID-19 who had presented to the institution during the surge of cases between late March and early August 2020. Almost all patients (95%) had at least one pre-ECMO comorbidity, including 12 (57.1%) with a medical history of obesity, 11 (52.4%) with hypertension, four (19%) with asthma, four (19%) with diabetes, three (14.3%) with a history of tobacco use and one (4.8%) with liver disease.
Treating COVID-19 and ARDS
All of the patients underwent VV ECMO support for acute respiratory distress syndrome (ARDS) secondary to COVID-19. Twenty patients (95.2%) received antibiotics prior to the initiation of VV ECMO, while 14 individuals (66.7%) received antiviral medications before VV ECMO treatment. During treatment, all 21 patients received anticoagulation, 19 (90.5%) received steroids and 20 (95.2%) required vasopressors, such as norepinephrine (Table).
| Table. Supportive Care and Therapies Delivered Before, During and After ECMO Use | |
| SOFA score 24 hours before ECMO cannulation | |
|---|---|
| Average ± SD | 9±2 |
| Median (first to third quartile) | 9 (8-10) |
| SOFA score 24 hours after ECMO cannulation | |
| Average ± SD | 8±3 |
| Median (first to third quartile) | 9 (7-11) |
| PaO2/FiO2 before ECMO cannulation | |
| Average ± SD | 107±34 |
| Median (first to third quartile) | 98 (77-131) |
| PaO2/FiO2 after ECMO cannulation | |
| Average ± SD | 219±106 |
| Median (first to third quartile) | 177 (137-299) |
| Median (first to third quartile) duration (days) of ECMO | 30 (21-89) |
| Other respiratory therapies used before/during/after cannulation | |
| BiPAP | 6 (28.6%) |
| HFNC | 17 (81.0%) |
| Intubation | 21 (100%) |
| Median (first to third quartile) duration (days) from intubation to ECMO | 5 (2-7) |
| Median (first to third quartile) duration (days) of intubation | 12 (7-24) |
| Prone positioning | 20 (95.2%) |
| Data are shown as n (%), where applicable. BiPAP, bilevel positive airway pressure; ECMO, extracorporeal membrane oxygenation; HFNC, high-flow nasal cannula; PaO2/FiO2, ratio of partial pressure of arterial oxygen to fraction of inspired oxygen; SOFA, Sequential Organ Failure Assessment | |
“These patients first underwent conditional respiratory therapy,” Sun said. “But since they all had severe ARDS, their lungs were not able to utilize the oxygen we provided them. So, we used VV ECMO to oxygenate their blood outside the body, which gave them time to heal on their own.”
In a presentation at the 2021 annual meeting of the American Society of Anesthesiologists (abstract A4040), Sun reported the median duration from endotracheal intubation to initiation of VV ECMO was five days; patients remained intubated for a median of 12 days. The median duration of ECMO support was 30 days.
The mean Sequential Organ Failure Assessment score was virtually unchanged before and after ECMO cannulation. In contrast, patients’ median PaO2/FiO2 (ratio of partial pressure of arterial oxygen to fraction of inspired oxygen) levels increased significantly after ECMO cannulation, from a mean of 107±34 24 hours before to a mean of 219±106 24 hours after.
{RELATED-HORIZONTAL}Analysis of patient outcomes found that all 21 patients reported the occurrence of at least one complication, either during or after ECMO support. The most common among these were bleeding (n=18; 85.7%), pneumonia (n=17; 81.0%) and pneumothorax (n=5; 23.8%). Other less common complications included cardiac arrest (n=2; 9.5%), cholecystitis (n=2; 9.5%), hemothorax (n=2; 9.5%), rhabdomyolysis (n=1; 4.8%) and encephalopathy (n=1; 4.8%). Four patients (28.6%) developed renal failure while on ECMO.
“We cannot say with conviction that these complications were caused by ECMO,” Sun said in an interview with Anesthesiology News. “They could be due to the ECMO or simply a product of the COVID-19 itself.”
Effectiveness of VV ECMO
Perhaps the study’s most telling results came in the form of patient discharge. Indeed, 18 patients (85.7%) were eventually discharged from the hospital, 11 to acute rehabilitation centers and seven to their homes. Three patients (14.3%) died.
“It’s a fairly impressive survival rate, but at the same time, we need to realize that this was not a randomized controlled trial,” Sun noted. “Therefore, we cannot definitively say that ECMO actually worked, because we didn’t have a control group. But the outcomes look promising.”
Indeed, clinicians at Rush University Medical Center have continued to use VV ECMO in these types of patients throughout the pandemic, a strategy they suggested other institutions employ, if resources allow.
“Unfortunately, some small community hospitals may not have ECMO machines available,” Sun said. “But if they are available, we would strongly recommend their use in these types of patients.”
According to Christopher W. Tam, MD, an assistant professor of clinical anesthesiology at Weill Cornell Medicine, in New York City, VV ECMO can be considered for patients who fail to respond to conventional ARDS medical management.
“Although the literature has not shown overwhelming mortality benefit in utilizing VV ECMO for ARDS, outcomes may be different in the COVID-19 population,” Tam said. “Further research is necessary to delineate if VV ECMO is more efficacious among patients with COVID-19 ARDS.”
As Tam discussed, patient selection for VV ECMO is of critical importance due to limited resources.
“VV ECMO should be reserved for hospital centers with the resources and experience to manage ECMO,” he noted. “A multidisciplinary team approach should be considered when deciding a patient’s candidacy for VV ECMO and for day-to-day medical management. It is also important to develop set criteria for cannulation and discontinuation of therapy to prevent a ‘bridge to nowhere’ situation.”
—Michael Vlessides
Sun and Tam reported no relevant financial disclosures.