Calibration and assessment of a fluid-filled catheter-transducer system for the measurement of ventricular diastolic pressures

• Published in: Physiological measurement 1998-08, Vol.19 (3), p.405-412
• Main Authors: Brennan, Edmund G, O'Hare, Neil J
• Format: Article
• Language: English
• Subjects: Animals; Blood Pressure Determination - methods; Catheterization - instrumentation; Catheterization - methods; Diastole; Humans; Ventricular Pressure
• ISSN: 0967-3334; 1361-6579
• DOI: 10.1088/0967-3334/19/3/009

A concise set of experiments is described which detail the calibration of a fluid-filled catheter-transducer system and the assessment of a widely used industrial algorithm for determining end-diastolic pressures using that system. First, the static response of the catheter-transducer system was evaluated in vitro by inserting the catheter into a graduated cylinder of saline. Twelve observations revealed a systematic undervaluation of pressure by the system of 1.78 mmHg with 95% limits of agreement ranging from -6.22 to 2.66 mmHg. Next, the dynamic response was evaluated in vivo by performing a transient step-response test. The system had an adequate dynamic response (fn = 11.12 Hz) for intraventricular pressure waveform replication but was considerably underdamped (beta = 0.16). Finally, the ability of the analysis software to detect the point of end-diastole and evaluate end-diastolic pressure was assessed by comparing system output with manual measurements of end-diastolic pressure in 12 patients. The mean difference between manually determined end-diastolic pressure and system output was 0.83 +/- 1.68 mm Hg. This difference is clinically insignificant and shows that the more noteworthy source of error is in the manometer-transducer emphasizing the importance of calibration and quality assurance of fluid-filled catheter-transducer systems for use in clinical cardiology or research.