Limitations of thermodilution ejection fraction: Degradation of frequency response by catheter mounting of fast-response thermistors

G. F. Maruschak, J. F. Schauble

Research output: Contribution to journalArticlepeer-review

Abstract

The present study examined whether catheter-mounting of a fast-response thermistor impaired the thermistor's ability to measure rapid temperature changes during thermodilution measurement of ejection fraction (EF). The response to a square-wave temperature change of six fast-response thermistors mounted on commercially available, pulmonary artery balloon-flotation catheters was compared to the response of a similar but unmounted fast-response thermistor. The response of the catheter-mounted fast-response thermistors recorded only 82% to 92% of a step-temperature change at 0.5 sec, and 88% to 96% of the step change at 1.0 sec. In contrast, the unmounted fast-response thermistor responded to 100% of the step change in 125 msec. The response of the catheter-mounted fast-response thermistors demonstrated an important slow component (second time constant) introduced by the catheter body, so that equilibration to a temperature change was not complete for about 6 sec. This slow equilibration lowered EF measured by thermodilution below true EF.

Original languageEnglish (US)
Pages (from-to)679-682
Number of pages4
JournalCritical care medicine
Volume13
Issue number8
DOIs
StatePublished - Jan 1 1985

ASJC Scopus subject areas

  • Critical Care and Intensive Care Medicine

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