Resonance artefacts in modern pressure monitoring systems.

Resonance in pressure monitoring catheters is a well-known problem which was studied several years ago. Current piezoelectric devices have mechanical properties providing a resonance frequency and damping factor that theoretically assure resonance-free data. However, in particular cases, the coupling between the device, the catheter, and the vascular compliance of the patient could introduce artefacts in clinical settings leading to wrong pressure waveforms and values displayed in the monitor. In this research work we study a laboratory model of a clinical setting to evaluate in which cases the compound (catheter and device) could cause resonances in an unacceptable range. The classical pop-test is expanded for analysing the effect of the catheter. Results indicate that the presence of different catheters may alter significantly the acquired signal, up to an unacceptable level. Particular care should be used in the selection of the appropriate catheter. In particular, smaller diameters introduce higher damping coefficient that could help in avoiding undesired oscillations.