Although extracorporeal membrane oxygenation (ECMO) continues to grow in use for patients with fulminant cardiac or respiratory failure unresponsive to conventional treatment, the rescue therapy is still associated with significant morbidity and mortality, according to a team of University of Chicago Hospitals researchers. Their national database study described the characteristics of patients undergoing the procedure, as well as their readmission and survival rates.
“There is not much information in terms of readmissions in ECMO patients,” said Atul Gupta, MBBS, clinical associate of anesthesia in the Chicago-based institution’s Department of Anesthesia. “So, we decided to look at this because it’s something that has not been reported before.”
Dr. Gupta, senior author Sajid S. Shahul, MD, and their co-investigators sought to examine the mortality, risk factors, outcomes and subsequent 30-day readmissions associated with ECMO use. They turned to the 2013 National Readmissions Database (NRD)—the largest readmission inpatient care database in the United States—which provides discharge data on approximately 15 million hospital stays. As Dr. Gupta described, the NRD provides data from 21 geographically diverse states and represents 49.3% of all hospitalizations. What’s more, NRD data can be weighted to produce nationally representative readmission rates across all hospitals and payors, including the uninsured.
As reported at the 2017 annual meeting of the Society of Cardiovascular Anesthesiologists (abstract SCA203), among 35,580,347 weighted national discharges, 2,488 admissions were for ECMO placement. The median age among these individuals was 49.3 years (95% CI, 45.41-53.46). The most common reasons for ECMO placement were acute myocardial infarction (MI; 12.1%), acute or chronic heart failure (5.3%), septicemia (4.2%), aortic valve disease (2.9%) and acute respiratory failure (2.7%). The mean length of stay during the ECMO implantation admission was 43 days. It was found among the 1,087 patients who were discharged, the mean 30-day readmission rate was 15.2%. The mean time to readmission from initial discharge was 11.4±14.2 days.
“We learned that readmissions were much higher among patients who were suffering from aortic valve disease and heart failure [35.7%] than those who were suffering acute respiratory failure or septicemia [4.0%; P<0.001],” Dr. Gupta told Anesthesiology News.
The most common reasons for readmission were acute heart failure (8.4%), lung transplant complications (6.0%), septicemia (4.7%) and respiratory failure (4.2%). An additional 2.8% of patients needed ECMO on readmission. The mortality rate during readmission was 8.1%; the most common reasons for death among readmitted patients included respiratory failure (36.4%), hemorrhagic complications (21.3%) and septicemia (16.9%). Meanwhile, in-hospital mortality associated with initial ECMO use was higher (56.3%).
Mortality was highest among patients with acute MI or aortic valve disease (61.1%) and lowest among those with acute respiratory failure (26.5%; P<0.0001). Significant predictors for death on ECMO include coagulopathy (odds ratio [OR], 1.40; 95% CI, 1.07-1.81), renal failure (OR, 1.46; 95% CI, 1.02-2.10), peripheral vascular disease (OR, 1.50; 95% CI, 1.01-2.22) and older age (OR, 1.91; 95% CI, 1.19-3.07). Not surprisingly, the mean length of stay was higher among survivors than nonsurvivors (42.9 vs. 17.9 days; P<0.0001).
Although most of the analysis provided expected results, it wasn’t without its surprises, as Dr. Gupta discussed. “We didn’t have much data on this subject, so we hope the study helps provide some insight into the therapy,” he said. “What proved surprising to us was that patients with sepsis and acute respiratory failure had much lower rates of readmission and mortality, compared to patients with heart failure or MI.”
Although ECMO patients in the analysis might have had a fairly high mortality rate, Dr. Gupta still acknowledged it as a meaningful, valid therapy in certain situations. “In terms of a rescue therapy, I don’t see ECMO as futile,” he said. “In fact, it’s actually useful in terms of health care dollars since the length of stay of ECMO nonsurvivors was significantly shorter than survivors [18 vs. 43 days] rather than the other way around. Indeed, with many other therapies, it’s the nonsurvivors who linger on the therapy longer than the survivors do.”
Nevertheless, the researchers recognized the need for more research and prospective studies to further elucidate the mechanisms of death and readmissions in ECMO patient populations.
“These may be administrative data, but it’s interesting that we got such a strong signal with respect to readmission rates and mortality,” he concluded.
Yet as Hilary P. Grocott, MD, commented, ECMO is an important lifesaving therapy, particularly if the need arises because of acute pulmonary dysfunction.
“Dr. Gupta and colleagues have reaffirmed in their study that the majority of these pulmonary patients survive to discharge, giving those practitioners who institute this therapy—often in very dire and uncertain circumstances—confidence that there are good odds at their patient surviving to discharge,” said Dr. Grocott, professor of anesthesia and perioperative medicine a nd surgery at the University of Manitoba, in Winnipeg. “Furthermore, when this does happen, only a relatively small number will require subsequent readmission.”