Experimental analysis of catheter-manometer systems in vitro and in vivo

S. F. Hipkins, A. J. Rutten, W. B. Runciman

Research output: Contribution to journalArticle

27 Citations (Scopus)

Abstract

The static and dynamic responses of two combinations of transducer amplifiers, pressure transducers, resonance elimination devices, extension tubing, and transcutaneous cannulae were tested in vitro using a sine-wave pressure generator, and in vivo by square-wave pressures generated by a 'fast-flush' device. In addition, carotid arterial blood pressure waveforms recorded by these systems in sheep, at two different heart rates, were compared with those simultaneously recorded with a catheter-tip pressure transducer. A new term, 'Working Heart Rate' is defined and allows for the prediction of the maximum heart rate up to which a system of given frequency response and damping coefficient should be accurate. When tested in vitro, all the monitoring systems were underdamped and resonated. The performance of all systems was improved by inclusion of an adjustable resonance elimination device but impaired by a nonadjustable resonance eliminator or by recording with an electronically filtered amplifier. When tested in vivo, the accuracy of mean and diastolic blood pressure measurement was not affected by any combination of heart rate, amplifier, length of extension tubing, or use of resonance eliminators. Both resonance elimination devices improved the performance of all systems. In contrast to predictions based on frequency response and damping, the smallest errors in systolic blood pressure were recorded using the electronic filter or the nonadjustable resonance eliminator. There were considerable and misleading differences between the frequency responses and damping coefficients calculated in vitro and those, for the same systems, derived from the in vivo fast-flush tests. It is conclouded that the most accurate and consistent readings of systolic blood pressure will be achieved with the use of either an electronic filter or a nonadjustable resonance eliminator

LanguageEnglish
Pages893-906
Number of pages14
JournalAnesthesiology
Volume71
Issue number6
DOIs
Publication statusPublished - 1989
Externally publishedYes

Keywords

  • blood pressure measurement: catheter-transducer systems
  • damping coefficients; dynamic responses; dynamic testing; resonant frequency

ASJC Scopus subject areas

  • Anesthesiology and Pain Medicine

Cite this

Hipkins, S. F. ; Rutten, A. J. ; Runciman, W. B. / Experimental analysis of catheter-manometer systems in vitro and in vivo. In: Anesthesiology. 1989 ; Vol. 71, No. 6. pp. 893-906.
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Experimental analysis of catheter-manometer systems in vitro and in vivo. / Hipkins, S. F.; Rutten, A. J.; Runciman, W. B.

In: Anesthesiology, Vol. 71, No. 6, 1989, p. 893-906.

Research output: Contribution to journalArticle

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