Detection of water-to-blood leakages in heat exchangers for cardiopulmonary bypass.

In the construction of heat exchangers, it is of great importance that when they are in use it shall be impossible for water to leak into the blood, as this might lead to hemolysis, intoxications, air emboli, or infection by microorganisms. In an investigation the aim of which was to discover water-to-blood leakages in the heat exchangers that are generally used during cardiopulmonary bypass, tests were carried out on 17 heat exchangers that are used all over the world and are supplied by five different makers. They included both disposable and nondisposable models. In six stainless steel heat exchangers, water leakages to the blood compartment were detected with the aid of helium. Some of these heat exchangers were brand new and had never been used. The size of the leakages was found to be sufficient to enable them to act as channels for the passage of foreign microorganisms.