[Present status of extracorporeal membrane oxygenation for adult respiratory failure]

In 1970s, survival rate in patients undergoing extracorporeal membrane oxygenation (ECMO) for acute respiratory failure was some around 10% even in sophisticated institutions. Most of them were treated by veno-arterial bypass along with mechanical ventilation with high air way pressure. Problems seen in this treatment modality were; difficulty in controlling bleeding and superimposed infection, mechanical problems of equipment (membrane lung, pumps, bypass circuit etc.), inadequate understanding of pathophysiology of respiratory failure. Lung injuries were also caused by high air way pressure and high fraction of inspired oxygen used in these patients. Above experience induced Kolobow and Gattinoni to use veno-venous bypass to extract metabolically produced carbon dioxide through membrane lungs and to supply oxygen through patient's own lung which is mechanically ventilated several times per minute with minimum concentration of inspired oxygen. Thus, lung damage caused by high air way pressure and oxygen can be preventable by giving lung time to rest and to heal. This treatment modality is called low frequency positive pressure ventilation with extracorporeal carbon dioxide removal (LFPPV-ECCO2R). The LFPPV-ECCO2R contributed much to raise the survival rate from 10% to 50%. Also better understanding of pathophysiology of acute respiratory failure and use of biocompatible materials like heparin-coated membrane lung and bypass circuit to minimize bleeding problem help much for better result. Successful cases are seen in younger patients with short duration of respiratory failure with reversible lung diseases. Bypass time is shorter in successful cases than that in unsuccessful cases. ECMO has revisited as Bartlett says.