Fig. 4From: How to measure blood pressure using an arterial catheter: a systematic 5-step approachQuantification of the fast-flush test [47]. The figure illustrates how to interpret the fast-flush test. The natural frequency (f) of the system is calculated by dividing the monitor speed by the peak to peak distance (P) of the oscillating waves. Additionally, the amplitude ratio of two consecutive resonant waves has to be calculated by dividing the amplitude of the smaller wave (A2) by the amplitude of the higher one (A1). The amplitude ratio is then plotted against f in a specific graph that shows three areas: adequate dynamic response, overdamping, and underdampingBack to article page