A Simple Flow Indicator for Use in Perfusion Fixation

In perfusion fixation, we have preferred gravity flow rather than a peristaltic forced flow because the latter may cause rupture of small blood vessels. One difficulty encountered in the gravity flow method is detection of flow stoppage, often caused by the formation of a blood clot. If this is apparent soon enough, steps can be taken to re-establish the flow, Flow stoppage is not usually detected for several minutes—resulting in poor fixation of the organ involved. To allow immediate detection of stoppage, a glass flow indicator (figure 1) was manufactured