Nearly 90% of US COVID-19 patients who qualified for, but did not receive, ECMO (extracorporeal membrane oxygenation) due to a shortage of resources during the height of the pandemic, died in the hospital, despite being young with few other health issues, according to a US study.
The Vanderbilt University Medical Center (VUMC) study, led by Whitney Gannon, MSN, director of Quality and Education for the Vanderbilt Extracorporeal Life Support Program (ECLS), analysed the total number of patients referred for ECMO in one referral region between 1 January 2021 and 31 August 2021.
They found that 90% of patients, for whom health system capacity to provide ECMO was unavailable, died in the hospital, compared with 43% mortality for patients who received ECMO, despite both groups being young and having limited comorbidities.
“Even when saving ECMO for the youngest, healthiest and sickest patients, we could only provide it to a fraction of people who qualified for it,” Gannon said. “I hope these data encourage hospitals and federal authorities to invest in the capacity to provide ECMO to more patients.”
Once a patient was determined to be medically eligible to receive ECMO, a separate assessment was performed of the health system’s resources to provide ECMO. When health system resources – equipment, personnel and intensive care unit beds – were not available, the patient was not transferred to an ECMO centre and did not receive ECMO.
Among 240 patients with COVID-19 referred for ECMO, 90 of them (37,5%) were determined to be medically eligible to receive ECMO and were included in the study. The median age was 40 years, and 25 (27,8%) were female.
For 35 patients (38.9%), the health system capacity to provide ECMO at a specialised centre was available; for 55 patients (61,1%), the health system capacity to provide ECMO at a specialised centre was unavailable.
Death before hospital discharge occurred in 15 of the 35 patients (42,9%) who received ECMO, compared with 49 of the 55 patients (89,1%) who did not receive ECMO.
“Throughout the pandemic, it has been challenging for many outside medicine to see the real-world impact of hospitals being strained or overwhelmed,” said co-author Dr Matthew Semler, assistant professor of Medicine at VUMC. “This article helps make those effects tangible. When the number of patients with COVID-19 exceeds hospital resources, young, healthy Americans die who otherwise would have lived.”
In total, the risk of death for patients who received ECMO at a specialised centre was approximately half of those who did not.
“Because some patients die despite receiving ECMO, there has been debate about how much benefit it provides. This study shows the answer is a huge benefit,” said senior author Dr Jonathan Casey, assistant professor of Medicine at VUMC.
“These data suggests that, on average, providing ECMO to two patients will save a life and give a young person the potential to live for decades,” he said.
The study was published in the American Journal of Respiratory and Critical Care Medicine.
Study details
Between Availability of ECMO and Mortality in COVID-19 Patients Eligible for ECMO: A Natural Experiment
Whitney Gannon, John Stokes, Sean Francois, Yatrik Patel, Meredith Pugh, Clayne Benson, Todd Rice, Matthew Bacchetta, Matthew Semler, Jonathan Casey.
Published in the American Journal of Respiratory and Critical Care Medicine on 2022
Methods
We analysed prospectively collected clinical data from all consecutive patients with SARS-CoV-2 who were referred for ECMO to a single centre between January 1, 2021 and August 31, 2021. For all referrals, a standardised case report form was used to record patient characteristics and the result of a multidisciplinary committee’s determination of whether the patient was eligible for ECMO.
Patients were considered medically eligible for ECMO if: (1) criteria for sufficiently severe ARDS, as defined by the EOLIA inclusion criteria, were present; (2) none of the following absolute contraindications was present: age greater than 60 years, body mass index (BMI) greater than 55 kg/m2 , duration of mechanical ventilation greater than 7 days, irreversible neurologic injury, chronic lung disease, active malignancy, or advanced multiple organ dysfunction; and three or fewer of the following relative contraindications were present: age greater than 50 years, BMI greater than 45 kg/m2 , presence of comorbidities, duration of mechanical ventilation greater than 4 days, presence of acute kidney injury, receipt of vasopressors, duration of hospitalisation greater than 14 days, or greater than 4 weeks since COVID-19 diagnosis.
Contraindications used to determine eligibility were selected by the committee based on published guidance, published data on factors associated with death committee based on published guidance, published data on factors associated with death during ECMO for COVID-19, and investigator experience.
After a patient was determined to be medically eligible to receive ECMO, a separate systematic assessment was performed of the health system’s resources to provide ECMO with regard to equipment, personnel, and intensive care unit bed availability. When health system resources were not available, the patient was not transferred to an ECMO centre and did not receive ECMO. When health system resources were available, the patient was transferred to an ECMO centre. No wait-list was maintained given the short eligibility window for ECMO after tracheal intubation and the long average duration of ECMO support for patients using existing ECMO resources. For patients transferred to the ECMO centre receiving the referral, the ECMO team performed cannulation at the referring facility and transported patients while receiving ECMO. For patients who were transferred to other regional ECMO centres,
cannulation was performed after arrival at the receiving facility.
All patients were followed until the time of death or hospital discharge by review of electronic health records or by telephone. Among patients determined to be eligible for ECMO, we compared those for whom health system capacity permitted transfer to receive ECMO at a specialised centre with those for whom health system capacity did not permit transfer to receive ECMO with regard to the primary outcome of all-cause in-hospital mortality, using Cox proportional hazards regression analysis adjusting for patients’ age, the presence of acute kidney injury, and receipt of vasopressors.
To determine whether the relationship between the availability of resources to provide ECMO and mortality was modified by changing COVID-19 outcomes over time, we tested for interactions between ECMO availability and the date of each ECMO consult. To examine whether hospital strain modified the relationship between the availability of resources to provide ECMO and mortality, we tested for interactions between ECMO availability and hospital strain, as represented by the 2-week average of COVID-19 hospitalisations and deaths in the region over the study period.
Results
Among the 240 patients with COVID-19 referred for ECMO, 26 patients (10,8%) did not complete the referral evaluation, 44 (18,3%) did not meet criteria for severity of lung injury, 80 (33,3%) had one or more absolute contraindications or greater than three relative contraindications, and 90 patients (37,5%) were determined to be medically eligible to receive ECMO and were included in this study. Median age was 40 years (IQR, 34-48) and 25 (27,8%) were female.
For 35 patients (38,9%), the health system capacity to provide ECMO at a specialised centre was available. Of these, 24 patients were cannulated at the referring hospital and transferred to the ECMO centre that received the referral and 11 patients were transferred to another regional ECMO centre, of whom eight were cannulated after arrival and three died or developed a contraindication to ECMO after transfer but before cannulation. For 55 patients (61,1%), the health system capacity to provide ECMO at a specialised centre was unavailable; none was transferred to an ECMO centre and none received ECMO. Characteristics at the time of referral were similar between patients for whom health system capacity permitted transfer to receive ECMO at a specialised centre and patients for whom health system capacity did not permit transfer to receive ECMO.
Death before hospital discharge occurred in 15 of the 35 patients (42.9%) for whom health system capacity permitted transfer to receive ECMO at a specialised centre compared with 49 of the 55 patients (89.1%) for whom health system capacity did not permit transfer to receive ECMO (adjusted hazard ratio 0.23; 95% confidence interval, 0.12 to 0.43; P < 0.001).
The effect of health system capacity to provide ECMO on mortality was not modified by time as measured by date of ECMO consult (p-value for interaction, 0.80) or by hospital strain as measured by the 2-week average number of hospitalisations or deaths in the state over the study period (p-value for interaction, 0.87 and 0.99, respectively). Results were similar in sensitivity analyses excluding days with multiple consults.
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