Class: BE-310
Group: M5
Members: Jeremy Cohen, Rebecca Lai, Rebecca Lintner, Luis Otoya, Brett Riccio
Date: Spring 1998
Full Text

Abstract:
The goal of the project was to determine the optimal thermodilution injection site for the different flow rates. A lab bench model consisting of a right atrium and ventricle was constructed using Tygon tubing and polyvinyl chloride pipes and fittings. Different flow rates ranging from .713 L/min to 3.19 L/min were run through the model and temperature measurements were taken using the catheter thermistor and standard thermometers. Injection sites were drilled into the side of both chambers so that the bolus could be introduced at both locations during the run. For each of the trials, a steady flow rate was run through the model. Six injections (three in the atrium and three in the ventricle) were then conducted one minute apart. For relatively low flow rates, .713-2.228 L/min, the ventricle was found to be the optimal injection site with an associated percent error of 15.11% compared to the atrium’s 17.4% error. For relatively high flow rates the results indicated that the most accurate injection site was the atrium which yielded a mean percent error of 17.27% when compared to the measured flow rates. The ventricular injection site at high flow yielded a mean percent error of 24.59%. When comparing the two rates between injection sites for a single measured flow rate, for example 3.65 + .349 L/min (atrium injection) and 3.317 + .342 L/min (ventricular injection), it can be seen that the two rates are within each other’s respective standard errors. This trend remained throughout the majority of the results, and thus was concluded that overall, the flow rates were quite similar despite the injection site. This lead us to believe that the model made of PVC lacked heat loss due to overwhelming conductive resistance properties of PVC. Consequently, because at relatively high flow rates, the accuracy and precision of injection in the atrium is greater, the atrium is most likely the proper place to inject in vivo to obtain reproducible and accurate results of cardiac output measurement.