An Improved Method for Drop Recording of Arterial or Venous Blood Flow.

Summary. An improved method for drop recording of blood flow is described. Its principle is that the blood drops collect and fall through a colorless incompressible fluid (silicone) instead of through air. The principal advantages of the silicone drop chamber over the original air drop chamber are largely the following: 1. The method is equally suitable for arterial and for venous blood flow. 2. The large drops, 7—9 per ml (as compared with 17—20 per ml when the drops fall in air from the same nozzle), enable relatively large blood flows to be recorded; 30 ml per minute has been recorded without difficulty. 3. No blood can splash on the chamber walls and thus affect the light intensity; the photocell may be quite sensitive to such changes. 4. There is no Windkessel effect which is of special importance in arterial recording. Pulse waves have less influence on the release of drops from the nozzle. The intervals between drops are almost as regular as those in recording of venous blood flow. 5. There are no errors in measurement during rapid and extreme changes of blood pressure.