Intracardiac surgery using the Kay-Anderson heart lung machine.

In 1951, Miller, Gibbon, and Gibbon,’ described a stationary screen oxygenator. Following this, Kay and Gaertner2 described a simplified stationary screen oxygenator. During the past year and a half, the stationary screen oxygenator has been further modified and simplified by Kay and Anderson.3 The changes are as follows: First, the apparatus is made of stainless steel, pyrex and teflon so that the entire unit can now be autoclaved. A second important improvement is the single chamber construction. The single chamber for the collection of venous, coronary sinus and chest blood also acts as an oxygenating blood reservoir, filter chamber and air trap. This single chamber construction has eliminated much tubing, many connectors, and several containers. The amount of blood necessary for a procedure has been reduced, and the problems of cleaning, assembling and mechanical failure, have been lessened. Venous blood from the superior and inferior vena cava enters one side of the chamber by gravity drainage. Oxygenated blood is pumped out of the other side of the container back to the patient’s arterial system. An internal circuit pump sends the blood from the venous side to the distribution chamber at the top. The blood runs down the screens and is oxygenated as 97 per cent oxygen and 2y per cent carbon dioxide mixture flows by the screens. The internal circuit pump is run slightly faster than the arterial pump so that a greater flow leaves the venous side of the chamber than there is blood returning from the patient. This creates a small flow of blood from the oxygenated side to the venous side of the chamber and this prevents any venous blood from entering the arterial side. In effect, there is a minimal left-to-right shunt in the bottom of the oxygenator. Blood aspirated from the heart and chest is returned by two large tubes to the venous side of the chamber. Blood in the bottom of the chamber acts as an air trap. A filter is incorporated on the oxygenating side.* The third important variation is a filmer which was first described by Anderson, Anderson and Kay4 in 1957. This device paints a film on the screens. This obviates the necessity of first creating a saline film by filling the apparatus with saline and draining the saline as blood is added. The filmer consists of a sheet of teflon with a slot 1/16 of an inch wide for each screen to fit into. A handle at