In five minutes, all the urea had moved into the salt water. The concept for building an artificial kidney was born. But it soon went underground.

In May 1940, Germany invaded the Netherlands. Rather than cooperate with Nazi sympathizers put in charge at Groningen, Dr. Kolff moved to a small hospital in Kampen, on the Zuider Zee (now called the Ijsselmeer), to wait out the war. While there, he set up Europe’s first blood bank and saved more than 800 people from Nazi labor camps by hiding them in his hospital. And he continued to work on the artificial kidney.

Image Dr. Willem J. Kolff, in the 1980s at his University of Utah lab, displaying an artificial heart, a version of which is still in use. Credit... University of Utah, Marriott Library

The device was an exemplar of Rube Goldberg ingenuity. It consisted of 50 yards of sausage casing wrapped around a wooden drum set into a salt solution. The patient’s blood was drawn from a wrist artery and fed into the casings. The drum was rotated, removing impurities. To get the blood safely back into the patient, Dr. Kolff copied the design of a water-pump coupling used in Ford motor engines. Later he used orange juice cans and a clothes washing machine to build his apparatuses.

The first 15 people placed on the machine died. Dr. Kolff made refinements, including the optimum use of blood thinners to prevent coagulation. In 1945, a 67-year-old woman —who had fallen into a coma from kidney failure while in jail after the liberation — was put on the machine for a far longer period than earlier patients and lived. Her first words on coming out of the coma were, “I’m going to divorce my husband.” She did — he was against the Nazis, and she was a collaborator — and lived seven more years.

In 1947, Dr. Kolff sent one of his artificial kidneys to Mount Sinai Hospital in Manhattan and began talking to American physicians also interested in artificial organs. Eventually, the machine underwent improvements that enabled it to be used regularly by people whose kidneys had failed irreparably. Tens of thousands of people now undergo dialysis three times a week, often as a bridge to kidney transplantation.

In 1950, Dr. Kolff joined the Cleveland Clinic Foundation, where he first had to improve his English, retake his medical exams and undergo naturalization to become an American citizen, which he accomplished in six years. Shortly thereafter, he developed a membrane oxygenator for bypass surgery and the first artificial heart, which, in 1957, kept a dog alive for 90 minutes.