Zwischenberger et al. ECMO Extracorporeal Cardiopulmonary Support in Critical Care, 2nd ed. © Extracorporeal Life Support Organization. 2000. Adapted with permission.

Since the 1970s, extracorporeal membrane oxygenation (ECMO)—a form of extracorporeal life support (ECLS) used in intensive care units—has been available as a last-resort treatment option for children and adults with acute heart or lung failure. Offered only in about 70 facilities nationwide,1 this procedure has long been associated with successful outcomes for neonatal patients.

But since the outbreak of the H1N1 virus 1 year ago, ECMO has proven effective in saving patients who present with life-threatening complications, such as progressive lung failure, severe acute respiratory distress syndrome (ARDS), or septic shock.

“ECMO allows the lungs to take a rest until they can be treated and healed,” says Tim Dickinson, director of clinical performance improvement for Hospital Clinical Services Group (HCSG), Nashville, Tenn, which provides contract perfusion services in 160 heart programs in 33 states.

Patients with severe cases of the H1N1 influenza may need as much as a month to recover their normal lung function. As prolonged use of a ventilator can damage the lungs, ECMO has emerged as a successful treatment option for patients who need a longer recovery time in order to survive. (As of February 12, H1N1 patients were averaging 280 hours on ECMO.2)

The Extracorporeal Life Support Organization (ELSO)—which is affiliated with the University of Michigan in Ann Arbor—reports a 72% survival rate for H1N1 patients who were placed on ECMO within 6 days of intubation between April and October of 2009.3 According to ELSO, ECMO was also used successfully during 2009’s H1N1 outbreak in Australia and New Zealand, with a 79% survival rate in 68 patients who did not respond to conventional treatments.3

An Increased Demand

ECMO’s success rate with H1N1 patients has increased the demand for the procedure. ECMO is typically performed on 1,500 to 2,000 patients in the United States annually, according to The Advisory Board Company, Washington, DC. In the past year alone, approximately 230 Americans with H1N1 were treated with ECMO.3

“In certain geographic areas of the country, such as Portland, Ore, and Houston, we at HCSG have seen a significant uptick in the number of ECMO procedures, and it has been related to the H1N1 outbreak,” Dickinson says.

ELSO Tracks ECMO Survival Rates and Usage Patterns Around the Globe

Founded in 1989, the Extracorporeal Life Support Organization (ELSO) serves as the central data point for all information related to extracorporeal membrane oxygenation (ECMO). Based at the University of Michigan in Ann Arbor, the international consortium of health care professionals and scientists collects ECMO-related data from 170 active centers around the world.

ELSO’s main registry comprises data from all known cases of extracorporeal life support (ECLS) performed. More than 40,000 ECLS procedures are on record, representing the cases of more than 27,000 newborns; 9,000 children; and 2,500 adults with respiratory and cardiac failure. The registry tracks the number of procedures performed, survival statistics, as well as the modalities used in each procedure. The registry also lists the number of patients currently on ECMO, in addition to the number of patients who are recovering in the hospital after an ECMO treatment.

The idea behind this centralized database is to use the aggregate data to help support clinical research, regulatory agencies, as well as the 115 individual ELSO member centers. Individual centers look to this data, which is stripped of any patient identifiers, for quality assurance purposes, and they can also incorporate these statistics into their clinical decisions regarding ECLS usage. The data can also be used to help improve ECLS technique and technology.

The Extracorporeal Life Support Organization, whose mission is to promote ECLS, is also involved in education and research efforts to aid in the development and evaluation of therapies to support failing organ systems. These educational programs are not limited to active ELSO centers alone—the organization also reaches out to the broader medical and lay communities.

In addition to the centralized registry that lists all forms of ECLS, ELSO also maintains registries for other novel forms of organ-system support. As part of this effort, ELSO is currently tracking the usage patterns of ECMO for H1N1 patients. The “H1N1 ECLS Registry” offers regular updates on the number of patients who have undergone the ECMO procedure as well as survival statistics. For the latest information, visit: [removed]www.elso.med.umich.edu/H1N1.htm[/removed]

Between April 2009 and January 2010, the Centers for Disease Control and Prevention estimates that 41 million to 84 million H1N1 cases occurred in the United States. During that same time, there were between 8,330 and 17,160 H1N1-related deaths.4 The fatality rate is similar to that of the seasonal flu; however, most deaths from H1N1 have occurred in adults under the age of 65.4

Although the number of H1N1 cases began to decline earlier this year thanks in part to the availability of the vaccine, Dickinson believes that ECMO’s high-visibility role in saving H1N1 patients’ lives will increase the popularity of the procedure for other applications.

“The H1N1 outbreak has really heightened the awareness of ECMO,” Dickinson says.

The Procedure

For patients with severe cases of H1N1, infection can spread very rapidly, which is why ELSO recommends referring candidates for ECMO to qualified facilities within their first 2 days in the ICU. Extracorporeal membrane oxygenation is indicated for patients on ventilators who require more than 80% oxygen concentration for adequate blood oxygenation.3 It is also recommended for H1N1 patients who require two or more medications to treat shock.

ECMO involves a modified heart-lung machine, which uses a self-regulating pump to act as the heart and an oxygenator to act as the lungs. The patient’s own heart and lungs continue to function, but much of the burden is shifted to the ECMO circuit so these organs can heal.

Cannulae are inserted into the patient’s blood vessels, and the blood is then pumped through the oxygenator, which removes carbon dioxide and restores oxygen to the blood before it is pumped back into the patient’s body. The two most common ECMO configurations are venoarterial and venovenous.

The majority of ECMO treatments are still performed on newborns, although there has been increased use of the procedure for adult patients.

“We use it in cardiac surgery when we’ve repaired the patient’s heart and it is still weak,” Dickinson says. “We can put [the individual] on ECMO and rest the heart and lungs for a few days or a few weeks until [the patient has] a chance to recover.”

While the principle behind ECMO is simple—to provide a partial bypass so the lungs and heart can rest and regain functionality—it is still a complex and risky procedure. The most common complications are bleeding associated with heparinization, technical failure, and neurologic sequelae secondary to the hypoxia and hemodynamic instability prior to the start of ECMO.5 Because of these risks, ECMO is indicated only for patients who have a 50% or higher chance of dying if they are treated by conventional means alone.

The Extracorporeal Life Support Organization urges facilities that do not have an ECMO program in place to avoid performing the procedure on site. Rather, stable patients on a ventilator who are potential candidates for ECMO should be transferred to a hospital with an existing ECMO program. This is because transporting patients who are already on ECMO is a high-risk proposition.

“When you have a patient on a ventilator and connected to the ECMO circuit, it gets very complex and tricky to transport them,” Dickinson says.

The Program

Despite ECMO’s success rates, the procedure’s availability remains limited to 70 or 80 facilities nationwide. The main reason for this is the expense of putting a program in place at a facility—hospitals must invest hundreds of thousands of dollars to train perfusionists to perform the procedure. As less than 2,000 patients receive ECMO treatments during a given year, hospitals that start programs are in danger of not having enough patients to make it a worthwhile investment.

“It is a huge undertaking in order to do it properly,” Dickinson says. “That’s why I think you are seeing ECMO done mostly at your tertiary or academic university medical centers.”

Not only is training expensive, but the procedure itself, which takes place in the ICU, can cost $2,000 per day.1 The recently published CESAR trial (Conventional Versus ECMO for Severe Adult Respiratory Failure) found, however, that although intervention with ECMO is more expensive than conventional treatment, it can be cost-effective overall when considering the long-term health of the patient.6

ECMO technology has advanced over the years, and continued improvements could eventually reduce costs while improving results.

Editor’s Note
To learn more about the CESAR Trial, go to “The CESAR Trial: ECMO Versus Conventional Ventilation

“The equipment keeps getting better and better,” Dickinson says. “The oxygenators are becoming smaller and better at minimizing damage to the blood. They’re smaller, so there’s less activation of the blood to a foreign surface, and they perform better than the older devices.”

One incentive to invest in an ECMO program is the possibility that another H1N1 outbreak could overwhelm the capacity of existing ECMO facilities, which also need the machines for traditional applications such as stabilizing neonatal patients. The advantage of starting a program is that patients can receive ECMO immediately on site—rather than having to be transferred to another hospital many miles away.

Although Dickinson notes that the number of H1N1 cases requiring ECMO has begun to decline in recent weeks, the demand for ECMO is not likely to go away anytime soon. He adds that the medical community will likely be inspired to consider new applications for the procedure—for example, ECMO has long been studied as a potential adjunct to CPR for patients in cardiac arrest.

“H1N1 has brought ECMO into the mainstream view of hospitals again,” Dickinson says. “I think it’s going to grow in popularity outside the H1N1 arena for people with respiratory disorders who need further ventilatory support.”


Ann H. Carlson is a contributing writer for RT. For further information, contact [email protected]

References

  1. Boschert S. Flu pandemic pushing demand for ECMO. CHEST Physician. November 3, 2009. Available at: www.chestnet.org/accp/article/flu-pandemic-pushing-demand-ecmo. Accessed February 23, 2010.
  2. Extracorporeal Life Support Organization. H1N1 ECLS Registry. Available at: [removed]www.elso.med.umich.edu/H1N1.htm[/removed]. Accessed February 23, 2010.
  3. Extracorporeal Life Support Organization.H1N1 Information. Available at: [removed]www.elso.med.umich.edu/H1N1Info.htm[/removed]. Accessed February 23, 2010.
  4. Centers for Disease Control and Prevention. CDC Estimates of 2009 H1N1 Influenza Cases, Hospitalizations and Deaths in the United States, April 2009–January 16, 2010. Available at: www.cdc.gov/h1n1flu/estimates_2009_h1n1.htm. Accessed February 23, 2010.
  5. University of Michigan Department of Surgery. Pediatric Surgery: ECMO. Available at: surgery.med.umich.edu/pediatric/research/section/ecmo.shtml. Accessed February 23, 2010.
  6. Peek GJ, Mugford M, Tiruvoipati R, et al. Efficacy and economic assessment of conventional ventilatory support versus extracorporeal membrane oxygenation for severe adult respiratory failure (CESAR): a multicentre randomised controlled trial. Lancet. 2009;374:1351-63.