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Correction of pressure waveforms recorded by fluid‐filled catheter recording systems: A new method using a transfer equation
Author(s) -
Lambermont B.,
Gerard P.,
Detry O.,
Kolh P.,
Potty P.,
D̂Orio V.,
Marcelle R.
Publication year - 1998
Publication title -
acta anaesthesiologica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.738
H-Index - 107
eISSN - 1399-6576
pISSN - 0001-5172
DOI - 10.1111/j.1399-6576.1998.tb05307.x
Subject(s) - waveform , catheter , medicine , distortion (music) , transfer function , linear regression , phase (matter) , signal (programming language) , biomedical engineering , acoustics , physics , mathematics , surgery , computer science , voltage , statistics , electrical engineering , amplifier , programming language , quantum mechanics , optoelectronics , cmos , engineering
Background: Pressure measuring systems using fluid‐filled catheters can result in the recording of distorted pressure waveforms. It results in phase delay, overestimation of systolic and, to a lesser extent, of diastolic pressure. We designed and evaluated a method to correct this pressure waveform distortion using an appropriate transfer equation obtained from the dynamic response of the fluid‐filled catheter. This transfer equation is based on the principle that a fluid‐filled catheter recording system is considered as an underdamped dynamic system fully characterized by its natural frequency (ω n and damping ratio (ζ). Methods: Pressure waveforms, simultaneously recorded in vitro or in vivo by a fluid‐filled catheter (Pc) and a micromanometertipped catheter (Pref), were used to validate the method. Dynamic response of the catheter used was obtained from a fastflush test. The corrected signal (Ppred) was obtained using con, Ω n ζ and the following transfer equation: d 2 P c /dt 2 + 2 ω n ζ dP c /dt+ω n 2 P c =C P pred (t) After correction of Pc, Ppred was compared, using a linear regression, with Pref taken as reference. Results: Our results showed that Ppred was fitted to Pref with excellent coefficient correlation (0.99). The mean error and the standard error of estimate were respectively –1.16 mmHg and 1.4 mmHg. Conclusion: This new method can convert the distorted pressure waveforms transmitted by any fluid‐filled catheters into high‐fidelity signals. It suppresses the phase delay and the over‐estimation of systolic pressure induced by fluid‐filled catheters.