Measurement of arterial pressure using catheter-transducer systems. Improvement using the Accudynamic.

The dynamic performance of arterial manometers depends upon the values of the natural frequency fo and the damping factor beta. Satisfactory reproduction of all arterial waveforms requires that fo should be greater than about 13 Hz; for an fo of 13 Hz, beta should have a value of 0.5, but, as fo increases, an increasing range of beta values is permissible. We measured fo and beta for two pressure transducers (Gould P23 Statham and Gould Disposable) in combination with Portex or Gould catheter tubing of lengths varying from 100 cm to 300 cm. All combinations were considerably underdamped, with the best having an fo of 30 Hz and a beta of 0.1. We also investigated the performance of a commercial device, the Accudynamic, designed to allow beta to be increased without affecting fo. We found that the Accudynamic worked well, allowing acceptable performance to be obtained from the Gould Disposable transducer with catheters up to 200 cm in length.