Excerpt
Extracorporeal membrane oxygenation (ECMO) is an expanded clinical application of cardiopulmonary bypass originally introduced in the mid 1950s, which allowed a longer period of support than the standard bubble and film type oxygenator and rapidly gained acceptance in cardiothoracic surgery. It was, therefore, logical to use ECMO temporarily in patients presenting with acute life-threatening hypoxemia. In a review published in 1973, Lefrak et al. [
1] reported a 15 % survival rate in 41 patients with refractory hypoxemia treated with membrane oxygenation. An identical survival rate was found by Gille and Bagniewski [
2], in 233 patients with acute respiratory distress syndrome (ARDS) treated with ECMO between 1966 and 1975. However, in the randomized study by Zapol et al. [
3], in patients presenting with respiratory distress, the survival among 42 patients assigned to ECMO was only 9.5 %, compared with 8.3 % in 48 patients assigned to standard mechanical ventilation. In a study published in 1994, of 40 patients suffering from severe ARDS, Morris et al. [
4] reported a 33 % survival rate among the 21 patients randomly assigned to veno-venous ECMO for the extracorporeal removal of CO
2, versus 42 % among the 19 patients assigned to mechanical ventilation. In 1996, a large randomized trial in the United Kingdom found ECMO effective in neonates presenting with severe, though potentially reversible, respiratory failure. Thereafter, the enthusiasm for using ECMO for respiratory distress seemed to wane, except for its use in neonates or for lung transplantation. By 2008, over 21,500 neonates had been treated with ECMO worldwide, of whom 76 % survived to hospital discharge [
5]. Meanwhile, among the few medical centers that continued to use ECMO for severe ARDS, 2 institutions, in the United States and Sweden, reported survival rates of 54 % in 100 patients and 76 % in 16 patients, respectively [
6,
7]. The Extracorporeal Life Support Organization reported retrospective, uncontrolled data collected from 1986 to 2006 in 1,473 adults with severe respiratory failure treated with ECMO, whose median age was 34 years, and of whom 50 % survived to discharge from the hospital [
8]. In that analysis, veno-venous bypass was associated with a higher survival than veno-arterial bypass. The conventional ventilatory support versus extracorporeal membrane oxygenation for severe adult respiratory failure (CESAR) trial, conducted in the United Kingdom between 2001 and 2006, showed that the transfer of adults with severe but potentially reversible respiratory failure, whose Murray score exceeded 3.0 or who had a pH of <7.20 on optimal conventional therapy, to a center with an ECMO-based management protocol, improved the survival significantly without severe residual disability [
9]. In the ECMO-assigned group 57 of 90 patients (63 %) survived, compared with 41 of 87 (47 %) in the conventional management group. Of the 90 patients assigned to the ECMO group, 68 did undergo ECMO, while 19 of the 22 remaining patients were transferred to an ECMO center and were managed by lung protective measures. While it was argued that the exclusion of the 22 patients who did not undergo ECMO would have canceled its positive effect, this study did show that transfer of patients to an ECMO center improved the clinical outcome. …
