Clinical Evaluation of Cardiac Output Estimation Based on Pulse Wave Transit Time

We will compare three methods for measuring cardiac output: esCCO, PAC, and ECOM. Cardiac output is an important physiological parameter that must be monitored closely during surgery and during an Intensive Care Unit (ICU) stay. The use of a pulmonary artery catheter (PAC) has been the gold standard for accurate cardiac output (CO) measurement. This method requires a catheter to be inserted into the pulmonary artery and cardiac output is indicated by the speed that a temperature gradient dissipates. While the use of the pulmonary artery catheter is widespread, inserting the pulmonary artery catheter is risky, time consuming and requires a high level of skill. For these reasons, new devices have been developed to measure cardiac output. A second method typically used is called ECOM (Endotracheal Cardiac Output Monitor). A device is inserted into the patient's throat that calculates cardiac output by measuring how electricity moves through the patient's chest. The third method, estimated Continuous Cardiac Output (esCCO), uses sensors placed on the patient's finger, arm and chest to calculate Pulse Wave Transit Time (PWTT); the time it takes for the heart beat pulse to travel through the patient's body. The esCCO system is FDA approved for safety and efficacy to measure noninvasive blood pressure and pulse oximetry. The purpose of this study is to assess whether the PSTT calculation provides a cardiac output measure that is comparable to the other methods. This study is sponsored by Nihon Kohden Corporation who owns and manufactures the esCCO system.