RESUMO
Blood flow measuring equipment and cardiac bypass pumps must be calibrated against a direct measurement of flow using timed collection. Single vessel timed collection systems have problems associated with their use. Repeated determinations of flow cannot be made rapidly, and frothing and fluid surface instability in the collecting vessel render the timing of a measured volume flow difficult and inaccurate. Collecting vessels which fill from the bottom may exert a changing back pressure on the source of flow. A semi-automated timed collection system is presented which overcomes these disadvantages. It has been used successfully to calibrate electromagnetic flowmeters and heart bypass pumps with 1% reproducibility or better. The system has also been used to measure coronary sinus flow directly in canine right heart bypass preparations.