A dynamic method for setting roller pumps nonocclusively reduces hemolysis and predicts retrograde flow.

In general, roller pumps are set almost occlusively despite evidence that nonocclusive settings cause less hemolysis. Almost-occlusive settings are used because of the concern that forward flow would not be accurately known if retrograde flow were allowed to occur through a nonocclusive gap. This article presents a dynamic method for setting roller pumps nonocclusively that overcomes the many difficulties of the "drop method" for setting occlusion. Studies were conducted to determine the effect of nonocclusive settings on pump flow and hemolysis generated; the results suggest that roller pumps can and should be set more nonocclusively than is the currently accepted standard to reduce pump related hemolysis without greatly affecting pump performance. The dynamic method allows retrograde flow to be easily predicted and corrected with an increase in pump speed.