A treatment used as a "last resort" for severe cases of COVID-19 could soon reach capacity as hospitals nationwide strain to meet the demands of a growing domestic outbreak.

In Japan, 24 patients with severe infections have been treated or continue to be treated using extracorporeal membrane oxygenation, or ECMO, a resource intensive but cutting-edge machine used occasionally to remedy serious lung and heart problems.

There are upwards of 1,300 ECMO machines available in the country, according to a survey released in March by the Japanese Society of Respiratory Care Medicine and the Japan Association of Clinical Engineers.