Abstract
Determination of cardiac output(CO) measured with Swan-Ganz catheter(SGC) depends on the time constant for heat transfer. Clinically used SGC's have thermistors with variable time constant. As a result, currently employed CO monitoring system is not accurate and use of the Stewart-Hamilton equation may cause marked errors The authors propose a new method of determining CO using SGC's with variable time constants using the Newton's law of cooling for analyzing the thermal dilution data. Blood flow rate calculated by the new method for a bovine blood with a perfectly mixtured tank mimicking a natural heart were insensitive to the time constants under the pulsatile and non-pulsatile flow conditions. Results were consistent regardless volume and temperature of the infused saline even after several tests hadd been performed.
