Infections through blood from heart-lung machine.

Of 657 cultures of blood from the heart-lung machine during operations performed with extra-corporeal circulation, 16 (2·4%) proved to be positive. Of these 16 patients, 12 showed no clinical infective symptoms. The case histories of the remaining four patients are presented. In three of these cases a plausible explanation for the infected perfusion blood was found: an infected aortic aneurysm, an infected aortic valve prosthesis, and mediastinitis. In only one case was the cause of the infection sought in the heart-lung machine.