The Science Journal of the American Association for Respiratory Care

2005 OPEN FORUM Abstracts

PNEUMATIC VS MANUAL INJECTION FOR THERMODILUTION CARDIAC OUTPUTS: IS THERE A DIFFERENCE?

Ahlsten KT, Appelquist JR, Black PJ, Cua AT, Gnahn ER, Helm RA, Loechler RM, Patterson EL, Peterson WV, Sampson KD, Ward JJ, RRT, Findlay JY, M.B.Ch.B., Plevak DJ, MD. University of Minnesota-Mayo Clinic College of Medicine, Rochester, MN

Background: The accurate determination of cardiac output (CO) is an important part of caring for patients that are critically ill. Thermodilution is a common method of determining CO that can be done either manually or using a pneumatic injector. We hypothesize that there will be no difference between pneumatic and manual methods. We compared these two methods by performing a bench study using a constant flow simulated circulatory system.

Methods: The simulated circulatory system consisting of a roller type pump (Travenol Laboratories, Inc Morton Grove, IL) and heated water bath (Instrumentation Laboratory Inc Boston, MA) was run at a consistent flow. Simulated CO was measured using a Hewlett Packard monitor system (Andover, MA). Ten people trained in obtaining CO used a 12 cc syringe to inject 10 cc of 5% dextrose injection at room temperature into a Swan-Ganz Thermodilution Paceport Catheter (Edwards Lifesciences LLC, Irvine, CA) that was placed in a simulated cardiovascular system. Each person performed 15 manual cardiac outputs and 15 with the pneumatic thermodilution injector (USCI Division, Billerica, MT). Each CO consisted of at least three outputs, the first of which was always discarded and two that were within 10% averaged. Results were analyzed by ANOVA and Student's T-test.

Results: The manual CO was significantly different from the pneumatic (5.47±0.24 vs. 5.63±0.14 L/min, p< 0.001). In addition there were significant differences between manual CO performed by different operators (p< 0.001).

Conclusions: While there were statistically significant differences between the two techniques, these differences are not clinically significant. Either technique would be clinically acceptable for measuring CO.

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