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

Northern California Institute of Research and Education, San Francisco Veterans Affairs Medical Center, Drexel University, Nihon Kohden

The specific aim of this study is to assess whether a device approved by the FDA to measure pulse oximetry can accurately estimate cardiac output.

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.

Patients undergoing surgery who will have their cardiac output monitored by pulmonary artery catheter (PAC) and endotracheal cardiac output monitoring (ECOM) during surgery and during post-surgical recovery, will also have sensors placed on the arm, finger and leg to calculate pulse wave transit time (PWTT) using the estimated Continuous Cardiac Output system (ecCCO).

A catheter is inserted into the pulmonary artery, through the internal jugular vein; cardiac output is indicated by the speed that a temperature gradient dissipates.

An FDA-approved medical device is inserted into the patient's throat; cardiac output is calculated by measuring how electricity moves through the chest.

Sensors are placed on the arm, finger and leg to calculate Pulse Wave Transit Time (PWTT); the time it takes for the pulse of the heartbeat to travel through the body.

6 Measurements of cardiac output derived from pulse oximeter measurements using the esCCO system were taken at each time point. The measurements deemed valid under the criteria in the protocol were averaged to represent the reference value at that point. The mean and standard deviation reported consist of the reference values from all time points measured. Data for this test were taken at the following timepoints: 1. Start of Sterenotomy; 2. Before Bypass; 3. 30 Min after bypass; 4. Closure; 5. ICU arrival; 6. 6 hours in ICU; 7. 12 Hours in ICU; 8. 18 Hours in ICU (if PAC still in); 9. 24 Hours in ICU (If PAC still in)

Measurements of cardiac output derived from a PAC (pulmonary artery catheter) using the standard thermodilution technique. At each time point, at least 6 measurements were taken. If, in the opinion of the clinician taking the readings, some of these were in error, more readings were taken to ensure accuracy. In no case were more than 18 readings taken. The points deemed valid by the clinician were averaged to obtain the reference value for that time point. The mean and standard deviation reported consisted of the reference values from all time points measured. Data for this test were taken at the following timepoints: 1. Start of Sterenotomy; 2. Before Bypass; 3. 30 Min after bypass; 4. Closure; 5. ICU arrival; 6. 6 hours in ICU; 7. 12 Hours in ICU; 8. 18 Hours in ICU (if PAC still in); 9. 24 Hours in ICU (If PAC still in)

Measurements of cardiac output derived from the Endotracheal Cardiac Output Monitor (ECOM): An FDA-approved medical device is inserted into the patient's throat; cardiac output is calculated by measuring how electricity moves through the chest.

Inclusion Criteria: Patients undergoing surgery where cardiac output will be measured with PAC and ECOM. Exclusion Criteria: Failure to obtain consent.