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Recommendation of a clinical impulse response analysis for catheter calibration-dumping coefficient and natural frequency are incomplete parameters for clinical evaluation.

Research paper by Hiroaki H Watanabe, Shin-ichi S Yagi, Akiyoshi A Namiki

Indexed on: 08 Mar '06Published on: 08 Mar '06Published in: Journal of Clinical Monitoring and Computing



Abstract

The damping coefficient and natural frequency are standard parameters for clinicians to evaluate the dynamic responses of pressure monitoring lines. But in fact, we had experienced some cases in which there were discrepancies between these parameters and frequency response curves. We tried to elucidate the defectiveness of the dumping coefficient and natural frequency with our new catheter calibration methods.At first we made a laboratory study with a function signal generator, a pressure wave converter, two pressure amplifiers and a personal computer. Using with our high-precision frequency response measurement method (step-response analysis) we clearly demonstrated the defectiveness of these parameters. Additionally a more sophisticated original method (clinical impulse response analysis) was also demonstrated in clinical recommendation, which makes it possible to measure true frequency response characteristics (system transfer function) without a function signal generator and a pressure wave converter, even in the operating room just after priming of the monitoring circuit without contamination.We recommend a clinical impulse response analysis for catheter calibration, instead of dumping coefficient and natural frequency.