Non invasive measurement / monitoring of cardiac output:

Recently, based on the well-known accepted Fick’s Principle, Novametrix introduced NICO (Novametrix NICO®) cardiac output measurement device that uses partial CO2 breathing to determine cardiac output non-invasively. The NICO® Cardiopulmonary Management System provides continual cardiac output monitoring. With this method, the cardiac output is computed on breath-by-breath measurements of CO2 elimination. Rebreathing measurements are made every three minutes for 35 seconds. Cardiac output is proportional to the change in CO2 elimination divided by the change in end tidal CO2 resulting from a brief rebreathing period. These measurements are accomplished and measured by the proprietary NICO Sensor, which periodically adds a rebreathing volume into the breathing circuit. In addition, NICO provides non invasive measurement of airway dead space. If arterial carbon dioxide tensions are known, physiological dead space can be calculated easily.  Several investigators have used this device to determine cardiac output and compare the results with conventional methods, such as pulmonary artery catheter measurements. The results are encouraging in patients with healthy lungs.1-6  Whereas the results are controversial when the lungs are diseased.7  There are several abstracts at American Society of Anesthesiologist’s Conference 2002/2001 that evaluated the usefulness of this new device.

References

1. Haryadi DG, Orr JA, Kuck K, McJames S, Westenskow DR. Partial CO2 rebreathing indirect Fick technique for non-invasive measurement of cardiac output.
J Clin Monit Comput. 2000;16(5-6):361-74.

2. Jaffe MB.  Partial CO2 rebreathing cardiac output–operating principles of the NICO system.
J Clin Monit Comput. 1999 Aug;15(6):387-401.

3. Neuhauser C, Muller M, Brau M, Scholz S, Boning O, Roth P, Hempelmann G. Partial CO(2) rebreathing technique versus thermodilution: measurement of cardiac output before and after operations with extracorporeal circulation.  Anaesthesist. 2002 Aug;51(8):625-33. German.

4. Odenstedt H, Stenqvist O, Lundin S. Clinical evaluation of a partial CO2 rebreathing technique for cardiac output monitoring in critically ill patients. Acta Anaesthesiol Scand. 2002 Feb;46(2):152-9.

5. Gedeon A, Krill P, Kristensen J, Gottlieb I. Noninvasive cardiac output determined with a new method based on gas exchange measurements and carbon dioxide rebreathing: A study in animals/pigs. J Clin Monit 1992;8:267-78.

6. Pianosi P, Hochman J. End-tidal estimates of arterial PCO2 for cardiac output measurements by CO2 rebreathing: a study in patients with cystic fibrosis and healthy controls. Pedatr Pulmonol 1996;22:154-60.