Inventors: Donald Van Slyke, James M. Neill, and John Plazin
How it began: In 1914, when Van Slyke became chief chemist of the newly opened Rockefeller Hospital, there were few chemical tests for evaluating a patient’s condition. During studies of diabetes, he needed a quantitative method to monitor blood pH and to measure the volume of oxygen and carbon dioxide in the blood.
What it does: The volume of gas from the blood in the reaction chamber is obtained by a vacuum from a mercury manometer. The liquid-filled glass jacket around the reaction chamber maintains a constant temperature. The pressure of the liberated and isolated gas in a known volume is recorded in millimeters of mercury.
Impact on medical science: The instrument made several significant advances in understanding the relationships between gases in blood and tissues, the role of electrolytes, and the nature of the acid-base balance of blood. Once ubiquitous in clinical research, the apparatus was replaced by colorimeters and pH meters.
Reference: Van Slyke, D.D., and Neill, J.M. The determination of gases in blood and other solutions by vacuum extraction and manometric measurement. I and II. Journal of Biological Chemistry 1924, 61:523-584.
Photo by Olga Nilova
Donald Van Slyke, James M. Neill, RU Hospital, manometric apparatus